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* [PATCHSET v12] io_uring IO interface
@ 2019-02-07 19:55 Jens Axboe
  2019-02-07 19:55 ` [PATCH 01/18] fs: add an iopoll method to struct file_operations Jens Axboe
                   ` (17 more replies)
  0 siblings, 18 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api; +Cc: hch, jmoyer, avi, jannh, viro

Here's v12 of the io_uring project. This is the Al Viro special, where
Al tries to beat into my head how UNIX fd passing will mess you up. I
think we have all cases handled now. I've added the resulting test case
into the liburing test/ directory.

Outside of that, various little cleanups and fixes, and a revert of
using FOLL_ANON to map IO buffers. This makes it fail with huge pages,
something that we can (and do want to) support. We're now back to just
checking for a file backing in the vma.

As far as I'm concerned, this project is ready to get staged for 5.1.
Please do review carefully so we can fix any minor nits that might still
exist.

The liburing git repo has a full set of man pages for this, though they
could probably still use a bit of polish. I'd also like to see a
io_uring(7) man page to describe the overall design of the project,
expect that in the not-so-distant future. You can clone that here:

git://git.kernel.dk/liburing

Patches are against 5.0-rc5, and can also be found in my io_uring branch
here:

git://git.kernel.dk/linux-block io_uring

Since v11:
- Get rid of the need for storing a files_struct
- Protect against release loop when UNIX fd passing is used
- Retain kiocb state for EAGAIN async retry
- Cleanup io memory accounting
- Revert to using non-FOLL_ANON, as we do want to support huge pages
- Fix uid leak
- Address various review comments
- Rebase on v5.0-rc5

 Documentation/filesystems/vfs.txt      |    3 +
 arch/x86/entry/syscalls/syscall_32.tbl |    3 +
 arch/x86/entry/syscalls/syscall_64.tbl |    3 +
 block/bio.c                            |   59 +-
 fs/Makefile                            |    1 +
 fs/block_dev.c                         |   19 +-
 fs/file.c                              |   15 +-
 fs/file_table.c                        |    9 +-
 fs/gfs2/file.c                         |    2 +
 fs/io_uring.c                          | 2741 ++++++++++++++++++++++++
 fs/iomap.c                             |   48 +-
 fs/xfs/xfs_file.c                      |    1 +
 include/linux/bio.h                    |   14 +
 include/linux/blk_types.h              |    1 +
 include/linux/file.h                   |    2 +
 include/linux/fs.h                     |   15 +-
 include/linux/iomap.h                  |    1 +
 include/linux/sched/user.h             |    2 +-
 include/linux/syscalls.h               |    8 +
 include/net/af_unix.h                  |    1 +
 include/uapi/asm-generic/unistd.h      |    8 +-
 include/uapi/linux/io_uring.h          |  142 ++
 init/Kconfig                           |    9 +
 kernel/sys_ni.c                        |    3 +
 net/unix/af_unix.c                     |    2 +-
 net/unix/garbage.c                     |    3 +
 26 files changed, 3073 insertions(+), 42 deletions(-)

-- 
Jens Axboe



^ permalink raw reply	[flat|nested] 42+ messages in thread

* [PATCH 01/18] fs: add an iopoll method to struct file_operations
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
                   ` (16 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

This new methods is used to explicitly poll for I/O completion for an
iocb.  It must be called for any iocb submitted asynchronously (that
is with a non-null ki_complete) which has the IOCB_HIPRI flag set.

The method is assisted by a new ki_cookie field in struct iocb to store
the polling cookie.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 Documentation/filesystems/vfs.txt | 3 +++
 include/linux/fs.h                | 2 ++
 2 files changed, 5 insertions(+)

diff --git a/Documentation/filesystems/vfs.txt b/Documentation/filesystems/vfs.txt
index 8dc8e9c2913f..761c6fd24a53 100644
--- a/Documentation/filesystems/vfs.txt
+++ b/Documentation/filesystems/vfs.txt
@@ -857,6 +857,7 @@ struct file_operations {
 	ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
 	ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
 	ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
+	int (*iopoll)(struct kiocb *kiocb, bool spin);
 	int (*iterate) (struct file *, struct dir_context *);
 	int (*iterate_shared) (struct file *, struct dir_context *);
 	__poll_t (*poll) (struct file *, struct poll_table_struct *);
@@ -902,6 +903,8 @@ otherwise noted.
 
   write_iter: possibly asynchronous write with iov_iter as source
 
+  iopoll: called when aio wants to poll for completions on HIPRI iocbs
+
   iterate: called when the VFS needs to read the directory contents
 
   iterate_shared: called when the VFS needs to read the directory contents
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 29d8e2cfed0e..dedcc2e9265c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -310,6 +310,7 @@ struct kiocb {
 	int			ki_flags;
 	u16			ki_hint;
 	u16			ki_ioprio; /* See linux/ioprio.h */
+	unsigned int		ki_cookie; /* for ->iopoll */
 } __randomize_layout;
 
 static inline bool is_sync_kiocb(struct kiocb *kiocb)
@@ -1787,6 +1788,7 @@ struct file_operations {
 	ssize_t (*write) (struct file *, const char __user *, size_t, loff_t *);
 	ssize_t (*read_iter) (struct kiocb *, struct iov_iter *);
 	ssize_t (*write_iter) (struct kiocb *, struct iov_iter *);
+	int (*iopoll)(struct kiocb *kiocb, bool spin);
 	int (*iterate) (struct file *, struct dir_context *);
 	int (*iterate_shared) (struct file *, struct dir_context *);
 	__poll_t (*poll) (struct file *, struct poll_table_struct *);
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 02/18] block: wire up block device iopoll method
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
  2019-02-07 19:55 ` [PATCH 01/18] fs: add an iopoll method to struct file_operations Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 03/18] block: add bio_set_polled() helper Jens Axboe
                   ` (15 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Just call blk_poll on the iocb cookie, we can derive the block device
from the inode trivially.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 58a4c1217fa8..f18d076a2596 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -293,6 +293,14 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+}
+
 static void blkdev_bio_end_io(struct bio *bio)
 {
 	struct blkdev_dio *dio = bio->bi_private;
@@ -410,6 +418,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 				bio->bi_opf |= REQ_HIPRI;
 
 			qc = submit_bio(bio);
+			WRITE_ONCE(iocb->ki_cookie, qc);
 			break;
 		}
 
@@ -2076,6 +2085,7 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read_iter	= blkdev_read_iter,
 	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
 	.mmap		= generic_file_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 03/18] block: add bio_set_polled() helper
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
  2019-02-07 19:55 ` [PATCH 01/18] fs: add an iopoll method to struct file_operations Jens Axboe
  2019-02-07 19:55 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 04/18] iomap: wire up the iopoll method Jens Axboe
                   ` (14 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

For the upcoming async polled IO, we can't sleep allocating requests.
If we do, then we introduce a deadlock where the submitter already
has async polled IO in-flight, but can't wait for them to complete
since polled requests must be active found and reaped.

Utilize the helper in the blockdev DIRECT_IO code.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c      |  4 ++--
 include/linux/bio.h | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index f18d076a2596..392e2bfb636f 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -247,7 +247,7 @@ __blkdev_direct_IO_simple(struct kiocb *iocb, struct iov_iter *iter,
 		task_io_account_write(ret);
 	}
 	if (iocb->ki_flags & IOCB_HIPRI)
-		bio.bi_opf |= REQ_HIPRI;
+		bio_set_polled(&bio, iocb);
 
 	qc = submit_bio(&bio);
 	for (;;) {
@@ -415,7 +415,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 		nr_pages = iov_iter_npages(iter, BIO_MAX_PAGES);
 		if (!nr_pages) {
 			if (iocb->ki_flags & IOCB_HIPRI)
-				bio->bi_opf |= REQ_HIPRI;
+				bio_set_polled(bio, iocb);
 
 			qc = submit_bio(bio);
 			WRITE_ONCE(iocb->ki_cookie, qc);
diff --git a/include/linux/bio.h b/include/linux/bio.h
index 7380b094dcca..f6f0a2b3cbc8 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -823,5 +823,19 @@ static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
 
 #endif /* CONFIG_BLK_DEV_INTEGRITY */
 
+/*
+ * Mark a bio as polled. Note that for async polled IO, the caller must
+ * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
+ * We cannot block waiting for requests on polled IO, as those completions
+ * must be found by the caller. This is different than IRQ driven IO, where
+ * it's safe to wait for IO to complete.
+ */
+static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
+{
+	bio->bi_opf |= REQ_HIPRI;
+	if (!is_sync_kiocb(kiocb))
+		bio->bi_opf |= REQ_NOWAIT;
+}
+
 #endif /* CONFIG_BLOCK */
 #endif /* __LINUX_BIO_H */
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 04/18] iomap: wire up the iopoll method
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (2 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 03/18] block: add bio_set_polled() helper Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 05/18] Add io_uring IO interface Jens Axboe
                   ` (13 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Store the request queue the last bio was submitted to in the iocb
private data in addition to the cookie so that we find the right block
device.  Also refactor the common direct I/O bio submission code into a
nice little helper.

Signed-off-by: Christoph Hellwig <hch@lst.de>

Modified to use bio_set_polled().

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/gfs2/file.c        |  2 ++
 fs/iomap.c            | 43 ++++++++++++++++++++++++++++---------------
 fs/xfs/xfs_file.c     |  1 +
 include/linux/iomap.h |  1 +
 4 files changed, 32 insertions(+), 15 deletions(-)

diff --git a/fs/gfs2/file.c b/fs/gfs2/file.c
index a2dea5bc0427..58a768e59712 100644
--- a/fs/gfs2/file.c
+++ b/fs/gfs2/file.c
@@ -1280,6 +1280,7 @@ const struct file_operations gfs2_file_fops = {
 	.llseek		= gfs2_llseek,
 	.read_iter	= gfs2_file_read_iter,
 	.write_iter	= gfs2_file_write_iter,
+	.iopoll		= iomap_dio_iopoll,
 	.unlocked_ioctl	= gfs2_ioctl,
 	.mmap		= gfs2_mmap,
 	.open		= gfs2_open,
@@ -1310,6 +1311,7 @@ const struct file_operations gfs2_file_fops_nolock = {
 	.llseek		= gfs2_llseek,
 	.read_iter	= gfs2_file_read_iter,
 	.write_iter	= gfs2_file_write_iter,
+	.iopoll		= iomap_dio_iopoll,
 	.unlocked_ioctl	= gfs2_ioctl,
 	.mmap		= gfs2_mmap,
 	.open		= gfs2_open,
diff --git a/fs/iomap.c b/fs/iomap.c
index 897c60215dd1..2ac9eb746d44 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1463,6 +1463,28 @@ struct iomap_dio {
 	};
 };
 
+int iomap_dio_iopoll(struct kiocb *kiocb, bool spin)
+{
+	struct request_queue *q = READ_ONCE(kiocb->private);
+
+	if (!q)
+		return 0;
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), spin);
+}
+EXPORT_SYMBOL_GPL(iomap_dio_iopoll);
+
+static void iomap_dio_submit_bio(struct iomap_dio *dio, struct iomap *iomap,
+		struct bio *bio)
+{
+	atomic_inc(&dio->ref);
+
+	if (dio->iocb->ki_flags & IOCB_HIPRI)
+		bio_set_polled(bio, dio->iocb);
+
+	dio->submit.last_queue = bdev_get_queue(iomap->bdev);
+	dio->submit.cookie = submit_bio(bio);
+}
+
 static ssize_t iomap_dio_complete(struct iomap_dio *dio)
 {
 	struct kiocb *iocb = dio->iocb;
@@ -1575,7 +1597,7 @@ static void iomap_dio_bio_end_io(struct bio *bio)
 	}
 }
 
-static blk_qc_t
+static void
 iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
 		unsigned len)
 {
@@ -1589,15 +1611,10 @@ iomap_dio_zero(struct iomap_dio *dio, struct iomap *iomap, loff_t pos,
 	bio->bi_private = dio;
 	bio->bi_end_io = iomap_dio_bio_end_io;
 
-	if (dio->iocb->ki_flags & IOCB_HIPRI)
-		flags |= REQ_HIPRI;
-
 	get_page(page);
 	__bio_add_page(bio, page, len, 0);
 	bio_set_op_attrs(bio, REQ_OP_WRITE, flags);
-
-	atomic_inc(&dio->ref);
-	return submit_bio(bio);
+	iomap_dio_submit_bio(dio, iomap, bio);
 }
 
 static loff_t
@@ -1700,9 +1717,6 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 				bio_set_pages_dirty(bio);
 		}
 
-		if (dio->iocb->ki_flags & IOCB_HIPRI)
-			bio->bi_opf |= REQ_HIPRI;
-
 		iov_iter_advance(dio->submit.iter, n);
 
 		dio->size += n;
@@ -1710,11 +1724,7 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 		copied += n;
 
 		nr_pages = iov_iter_npages(&iter, BIO_MAX_PAGES);
-
-		atomic_inc(&dio->ref);
-
-		dio->submit.last_queue = bdev_get_queue(iomap->bdev);
-		dio->submit.cookie = submit_bio(bio);
+		iomap_dio_submit_bio(dio, iomap, bio);
 	} while (nr_pages);
 
 	/*
@@ -1925,6 +1935,9 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 	if (dio->flags & IOMAP_DIO_WRITE_FUA)
 		dio->flags &= ~IOMAP_DIO_NEED_SYNC;
 
+	WRITE_ONCE(iocb->ki_cookie, dio->submit.cookie);
+	WRITE_ONCE(iocb->private, dio->submit.last_queue);
+
 	/*
 	 * We are about to drop our additional submission reference, which
 	 * might be the last reference to the dio.  There are three three
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index e47425071e65..60c2da41f0fc 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -1203,6 +1203,7 @@ const struct file_operations xfs_file_operations = {
 	.write_iter	= xfs_file_write_iter,
 	.splice_read	= generic_file_splice_read,
 	.splice_write	= iter_file_splice_write,
+	.iopoll		= iomap_dio_iopoll,
 	.unlocked_ioctl	= xfs_file_ioctl,
 #ifdef CONFIG_COMPAT
 	.compat_ioctl	= xfs_file_compat_ioctl,
diff --git a/include/linux/iomap.h b/include/linux/iomap.h
index 9a4258154b25..0fefb5455bda 100644
--- a/include/linux/iomap.h
+++ b/include/linux/iomap.h
@@ -162,6 +162,7 @@ typedef int (iomap_dio_end_io_t)(struct kiocb *iocb, ssize_t ret,
 		unsigned flags);
 ssize_t iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 		const struct iomap_ops *ops, iomap_dio_end_io_t end_io);
+int iomap_dio_iopoll(struct kiocb *kiocb, bool spin);
 
 #ifdef CONFIG_SWAP
 struct file;
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 05/18] Add io_uring IO interface
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (3 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 04/18] iomap: wire up the iopoll method Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 20:15   ` Keith Busch
  2019-02-07 19:55 ` [PATCH 06/18] io_uring: add fsync support Jens Axboe
                   ` (12 subsequent siblings)
  17 siblings, 1 reply; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

The submission queue (SQ) and completion queue (CQ) rings are shared
between the application and the kernel. This eliminates the need to
copy data back and forth to submit and complete IO.

IO submissions use the io_uring_sqe data structure, and completions
are generated in the form of io_uring_sqe data structures. The SQ
ring is an index into the io_uring_sqe array, which makes it possible
to submit a batch of IOs without them being contiguous in the ring.
The CQ ring is always contiguous, as completion events are inherently
unordered, and hence any io_uring_cqe entry can point back to an
arbitrary submission.

Two new system calls are added for this:

io_uring_setup(entries, params)
	Sets up a context for doing async IO. On success, returns a file
	descriptor that the application can mmap to gain access to the
	SQ ring, CQ ring, and io_uring_sqes.

io_uring_enter(fd, to_submit, min_complete, flags, sigset, sigsetsize)
	Initiates IO against the rings mapped to this fd, or waits for
	them to complete, or both. The behavior is controlled by the
	parameters passed in. If 'to_submit' is non-zero, then we'll
	try and submit new IO. If IORING_ENTER_GETEVENTS is set, the
	kernel will wait for 'min_complete' events, if they aren't
	already available. It's valid to set IORING_ENTER_GETEVENTS
	and 'min_complete' == 0 at the same time, this allows the
	kernel to return already completed events without waiting
	for them. This is useful only for polling, as for IRQ
	driven IO, the application can just check the CQ ring
	without entering the kernel.

With this setup, it's possible to do async IO with a single system
call. Future developments will enable polled IO with this interface,
and polled submission as well. The latter will enable an application
to do IO without doing ANY system calls at all.

For IRQ driven IO, an application only needs to enter the kernel for
completions if it wants to wait for them to occur.

Each io_uring is backed by a workqueue, to support buffered async IO
as well. We will only punt to an async context if the command would
need to wait for IO on the device side. Any data that can be accessed
directly in the page cache is done inline. This avoids the slowness
issue of usual threadpools, since cached data is accessed as quickly
as a sync interface.

Sample application: http://git.kernel.dk/cgit/fio/plain/t/io_uring.c

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 arch/x86/entry/syscalls/syscall_32.tbl |    2 +
 arch/x86/entry/syscalls/syscall_64.tbl |    2 +
 fs/Makefile                            |    1 +
 fs/io_uring.c                          | 1174 ++++++++++++++++++++++++
 include/linux/fs.h                     |    9 +
 include/linux/syscalls.h               |    6 +
 include/uapi/asm-generic/unistd.h      |    6 +-
 include/uapi/linux/io_uring.h          |   95 ++
 init/Kconfig                           |    9 +
 kernel/sys_ni.c                        |    2 +
 net/unix/garbage.c                     |    3 +
 11 files changed, 1308 insertions(+), 1 deletion(-)
 create mode 100644 fs/io_uring.c
 create mode 100644 include/uapi/linux/io_uring.h

diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 3cf7b533b3d1..481c126259e9 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -398,3 +398,5 @@
 384	i386	arch_prctl		sys_arch_prctl			__ia32_compat_sys_arch_prctl
 385	i386	io_pgetevents		sys_io_pgetevents		__ia32_compat_sys_io_pgetevents
 386	i386	rseq			sys_rseq			__ia32_sys_rseq
+425	i386	io_uring_setup		sys_io_uring_setup		__ia32_sys_io_uring_setup
+426	i386	io_uring_enter		sys_io_uring_enter		__ia32_sys_io_uring_enter
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index f0b1709a5ffb..6a32a430c8e0 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -343,6 +343,8 @@
 332	common	statx			__x64_sys_statx
 333	common	io_pgetevents		__x64_sys_io_pgetevents
 334	common	rseq			__x64_sys_rseq
+425	common	io_uring_setup		__x64_sys_io_uring_setup
+426	common	io_uring_enter		__x64_sys_io_uring_enter
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/Makefile b/fs/Makefile
index 293733f61594..8e15d6fc4340 100644
--- a/fs/Makefile
+++ b/fs/Makefile
@@ -30,6 +30,7 @@ obj-$(CONFIG_TIMERFD)		+= timerfd.o
 obj-$(CONFIG_EVENTFD)		+= eventfd.o
 obj-$(CONFIG_USERFAULTFD)	+= userfaultfd.o
 obj-$(CONFIG_AIO)               += aio.o
+obj-$(CONFIG_IO_URING)		+= io_uring.o
 obj-$(CONFIG_FS_DAX)		+= dax.o
 obj-$(CONFIG_FS_ENCRYPTION)	+= crypto/
 obj-$(CONFIG_FILE_LOCKING)      += locks.o
diff --git a/fs/io_uring.c b/fs/io_uring.c
new file mode 100644
index 000000000000..39a6cd14f0ec
--- /dev/null
+++ b/fs/io_uring.c
@@ -0,0 +1,1174 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Shared application/kernel submission and completion ring pairs, for
+ * supporting fast/efficient IO.
+ *
+ * Copyright (C) 2018-2019 Jens Axboe
+ */
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/errno.h>
+#include <linux/syscalls.h>
+#include <linux/compat.h>
+#include <linux/refcount.h>
+#include <linux/uio.h>
+
+#include <linux/sched/signal.h>
+#include <linux/fs.h>
+#include <linux/file.h>
+#include <linux/fdtable.h>
+#include <linux/mm.h>
+#include <linux/mman.h>
+#include <linux/mmu_context.h>
+#include <linux/percpu.h>
+#include <linux/slab.h>
+#include <linux/workqueue.h>
+#include <linux/blkdev.h>
+#include <linux/net.h>
+#include <net/sock.h>
+#include <net/af_unix.h>
+#include <linux/anon_inodes.h>
+#include <linux/sched/mm.h>
+#include <linux/uaccess.h>
+#include <linux/nospec.h>
+
+#include <uapi/linux/io_uring.h>
+
+#include "internal.h"
+
+#define IORING_MAX_ENTRIES	4096
+
+struct io_uring {
+	u32 head ____cacheline_aligned_in_smp;
+	u32 tail ____cacheline_aligned_in_smp;
+};
+
+struct io_sq_ring {
+	struct io_uring		r;
+	u32			ring_mask;
+	u32			ring_entries;
+	u32			dropped;
+	u32			flags;
+	u32			array[];
+};
+
+struct io_cq_ring {
+	struct io_uring		r;
+	u32			ring_mask;
+	u32			ring_entries;
+	u32			overflow;
+	struct io_uring_cqe	cqes[];
+};
+
+struct io_ring_ctx {
+	struct {
+		struct percpu_ref	refs;
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		unsigned int		flags;
+		bool			compat;
+
+		/* SQ ring */
+		struct io_sq_ring	*sq_ring;
+		unsigned		cached_sq_head;
+		unsigned		sq_entries;
+		unsigned		sq_mask;
+		struct io_uring_sqe	*sq_sqes;
+	} ____cacheline_aligned_in_smp;
+
+	/* IO offload */
+	struct workqueue_struct	*sqo_wq;
+	struct mm_struct	*sqo_mm;
+
+	struct {
+		/* CQ ring */
+		struct io_cq_ring	*cq_ring;
+		unsigned		cached_cq_tail;
+		unsigned		cq_entries;
+		unsigned		cq_mask;
+		struct wait_queue_head	cq_wait;
+		struct fasync_struct	*cq_fasync;
+	} ____cacheline_aligned_in_smp;
+
+	struct user_struct	*user;
+
+	struct completion	ctx_done;
+
+	struct {
+		struct mutex		uring_lock;
+		wait_queue_head_t	wait;
+	} ____cacheline_aligned_in_smp;
+
+	struct {
+		spinlock_t		completion_lock;
+	} ____cacheline_aligned_in_smp;
+
+#if defined(CONFIG_NET)
+	struct socket		*ring_sock;
+#endif
+};
+
+struct sqe_submit {
+	const struct io_uring_sqe	*sqe;
+	unsigned short			index;
+	bool				has_user;
+};
+
+struct io_kiocb {
+	struct kiocb		rw;
+
+	struct sqe_submit	submit;
+
+	struct io_ring_ctx	*ctx;
+	struct list_head	list;
+	unsigned int		flags;
+#define REQ_F_FORCE_NONBLOCK	1	/* inline submission attempt */
+	u64			user_data;
+
+	struct work_struct	work;
+};
+
+#define IO_PLUG_THRESHOLD		2
+
+static struct kmem_cache *req_cachep;
+
+static const struct file_operations io_uring_fops;
+
+struct sock *io_uring_get_socket(struct file *file)
+{
+#if defined(CONFIG_NET)
+	if (file->f_op == &io_uring_fops) {
+		struct io_ring_ctx *ctx = file->private_data;
+
+		return ctx->ring_sock->sk;
+	}
+#endif
+	return NULL;
+}
+
+static void io_ring_ctx_ref_free(struct percpu_ref *ref)
+{
+	struct io_ring_ctx *ctx = container_of(ref, struct io_ring_ctx, refs);
+
+	complete(&ctx->ctx_done);
+}
+
+static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
+{
+	struct io_ring_ctx *ctx;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	if (percpu_ref_init(&ctx->refs, io_ring_ctx_ref_free, 0, GFP_KERNEL)) {
+		kfree(ctx);
+		return NULL;
+	}
+
+	ctx->flags = p->flags;
+	init_waitqueue_head(&ctx->cq_wait);
+	init_completion(&ctx->ctx_done);
+	mutex_init(&ctx->uring_lock);
+	init_waitqueue_head(&ctx->wait);
+	spin_lock_init(&ctx->completion_lock);
+	return ctx;
+}
+
+static void io_commit_cqring(struct io_ring_ctx *ctx)
+{
+	struct io_cq_ring *ring = ctx->cq_ring;
+
+	if (ctx->cached_cq_tail != ring->r.tail) {
+		/* order cqe stores with ring update */
+		smp_wmb();
+		WRITE_ONCE(ring->r.tail, ctx->cached_cq_tail);
+		/* write side barrier of tail update, app has read side */
+		smp_wmb();
+
+		if (wq_has_sleeper(&ctx->cq_wait)) {
+			wake_up_interruptible(&ctx->cq_wait);
+			kill_fasync(&ctx->cq_fasync, SIGIO, POLL_IN);
+		}
+	}
+}
+
+static struct io_uring_cqe *io_get_cqring(struct io_ring_ctx *ctx)
+{
+	struct io_cq_ring *ring = ctx->cq_ring;
+	unsigned tail;
+
+	tail = ctx->cached_cq_tail;
+	smp_rmb();
+	if (tail + 1 == READ_ONCE(ring->r.head))
+		return NULL;
+
+	ctx->cached_cq_tail++;
+	return &ring->cqes[tail & ctx->cq_mask];
+}
+
+static void io_cqring_fill_event(struct io_ring_ctx *ctx, u64 ki_user_data,
+				 long res, unsigned ev_flags)
+{
+	struct io_uring_cqe *cqe;
+
+	/*
+	 * If we can't get a cq entry, userspace overflowed the
+	 * submission (by quite a lot). Increment the overflow count in
+	 * the ring.
+	 */
+	cqe = io_get_cqring(ctx);
+	if (cqe) {
+		cqe->user_data = ki_user_data;
+		cqe->res = res;
+		cqe->flags = ev_flags;
+	} else
+		ctx->cq_ring->overflow++;
+}
+
+static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 ki_user_data,
+				long res, unsigned ev_flags)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&ctx->completion_lock, flags);
+	io_cqring_fill_event(ctx, ki_user_data, res, ev_flags);
+	io_commit_cqring(ctx);
+	spin_unlock_irqrestore(&ctx->completion_lock, flags);
+
+	if (waitqueue_active(&ctx->wait))
+		wake_up(&ctx->wait);
+}
+
+static void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs)
+{
+	percpu_ref_put_many(&ctx->refs, refs);
+
+	if (waitqueue_active(&ctx->wait))
+		wake_up(&ctx->wait);
+}
+
+static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx)
+{
+	struct io_kiocb *req;
+
+	if (!percpu_ref_tryget(&ctx->refs))
+		return NULL;
+
+	req = kmem_cache_alloc(req_cachep, __GFP_NOWARN);
+	if (req) {
+		req->ctx = ctx;
+		req->flags = 0;
+		return req;
+	}
+
+	io_ring_drop_ctx_refs(ctx, 1);
+	return NULL;
+}
+
+static void io_free_req(struct io_kiocb *req)
+{
+	io_ring_drop_ctx_refs(req->ctx, 1);
+	kmem_cache_free(req_cachep, req);
+}
+
+static void kiocb_end_write(struct kiocb *kiocb)
+{
+	if (kiocb->ki_flags & IOCB_WRITE) {
+		struct inode *inode = file_inode(kiocb->ki_filp);
+
+		/*
+		 * Tell lockdep we inherited freeze protection from submission
+		 * thread.
+		 */
+		if (S_ISREG(inode->i_mode))
+			__sb_writers_acquired(inode->i_sb, SB_FREEZE_WRITE);
+		file_end_write(kiocb->ki_filp);
+	}
+}
+
+static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
+{
+	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
+
+	kiocb_end_write(kiocb);
+
+	fput(kiocb->ki_filp);
+	io_cqring_add_event(req->ctx, req->user_data, res, 0);
+	io_free_req(req);
+}
+
+/*
+ * If we tracked the file through the SCM inflight mechanism, we could support
+ * any file. For now, just ensure that anything potentially problematic is done
+ * inline.
+ */
+static bool io_file_supports_async(struct file *file)
+{
+	umode_t mode = file_inode(file)->i_mode;
+
+	if (S_ISBLK(mode) || S_ISCHR(mode))
+		return true;
+	if (S_ISREG(mode) && file->f_op != &io_uring_fops)
+		return true;
+
+	return false;
+}
+
+static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+		      bool force_nonblock)
+{
+	struct kiocb *kiocb = &req->rw;
+	unsigned ioprio;
+	int fd, ret;
+
+	/* For -EAGAIN retry, everything is already prepped */
+	if (kiocb->ki_filp)
+		return 0;
+
+	fd = READ_ONCE(sqe->fd);
+	kiocb->ki_filp = fget(fd);
+	if (unlikely(!kiocb->ki_filp))
+		return -EBADF;
+	if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
+		force_nonblock = false;
+	kiocb->ki_pos = READ_ONCE(sqe->off);
+	kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
+	kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
+
+	ioprio = READ_ONCE(sqe->ioprio);
+	if (ioprio) {
+		ret = ioprio_check_cap(ioprio);
+		if (ret)
+			goto out_fput;
+
+		kiocb->ki_ioprio = ioprio;
+	} else
+		kiocb->ki_ioprio = get_current_ioprio();
+
+	ret = kiocb_set_rw_flags(kiocb, READ_ONCE(sqe->rw_flags));
+	if (unlikely(ret))
+		goto out_fput;
+	if (force_nonblock) {
+		kiocb->ki_flags |= IOCB_NOWAIT;
+		req->flags |= REQ_F_FORCE_NONBLOCK;
+	}
+	if (kiocb->ki_flags & IOCB_HIPRI) {
+		ret = -EINVAL;
+		goto out_fput;
+	}
+
+	kiocb->ki_complete = io_complete_rw;
+	return 0;
+out_fput:
+	fput(kiocb->ki_filp);
+	return ret;
+}
+
+static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
+{
+	switch (ret) {
+	case -EIOCBQUEUED:
+		break;
+	case -ERESTARTSYS:
+	case -ERESTARTNOINTR:
+	case -ERESTARTNOHAND:
+	case -ERESTART_RESTARTBLOCK:
+		/*
+		 * We can't just restart the syscall, since previously
+		 * submitted sqes may already be in progress. Just fail this
+		 * IO with EINTR.
+		 */
+		ret = -EINTR;
+		/* fall through */
+	default:
+		kiocb->ki_complete(kiocb, ret, 0);
+	}
+}
+
+static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
+			   const struct sqe_submit *s, struct iovec **iovec,
+			   struct iov_iter *iter)
+{
+	const struct io_uring_sqe *sqe = s->sqe;
+	void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
+	size_t sqe_len = READ_ONCE(sqe->len);
+
+	if (!s->has_user)
+		return EFAULT;
+
+#ifdef CONFIG_COMPAT
+	if (ctx->compat)
+		return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
+						iovec, iter);
+#endif
+
+	return import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter);
+}
+
+static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
+		       bool force_nonblock)
+{
+	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct kiocb *kiocb = &req->rw;
+	struct iov_iter iter;
+	struct file *file;
+	ssize_t ret;
+
+	ret = io_prep_rw(req, s->sqe, force_nonblock);
+	if (ret)
+		return ret;
+	file = kiocb->ki_filp;
+
+	ret = -EBADF;
+	if (unlikely(!(file->f_mode & FMODE_READ)))
+		goto out_fput;
+	ret = -EINVAL;
+	if (unlikely(!file->f_op->read_iter))
+		goto out_fput;
+
+	ret = io_import_iovec(req->ctx, READ, s, &iovec, &iter);
+	if (ret)
+		goto out_fput;
+
+	ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_iter_count(&iter));
+	if (!ret) {
+		ssize_t ret2;
+
+		/* Catch -EAGAIN return for forced non-blocking submission */
+		ret2 = call_read_iter(file, kiocb, &iter);
+		if (!force_nonblock || ret2 != -EAGAIN)
+			io_rw_done(kiocb, ret2);
+		else
+			ret = -EAGAIN;
+	}
+	kfree(iovec);
+out_fput:
+	/* Hold on to the file for -EAGAIN */
+	if (unlikely(ret && ret != -EAGAIN))
+		fput(file);
+	return ret;
+}
+
+static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
+			bool force_nonblock)
+{
+	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
+	struct kiocb *kiocb = &req->rw;
+	struct iov_iter iter;
+	struct file *file;
+	ssize_t ret;
+
+	ret = io_prep_rw(req, s->sqe, force_nonblock);
+	if (ret)
+		return ret;
+	/* Hold on to the file for -EAGAIN */
+	if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT))
+		return -EAGAIN;
+
+	ret = -EBADF;
+	file = kiocb->ki_filp;
+	if (unlikely(!(file->f_mode & FMODE_WRITE)))
+		goto out_fput;
+	ret = -EINVAL;
+	if (unlikely(!file->f_op->write_iter))
+		goto out_fput;
+
+	ret = io_import_iovec(req->ctx, WRITE, s, &iovec, &iter);
+	if (ret)
+		goto out_fput;
+
+	ret = rw_verify_area(WRITE, file, &kiocb->ki_pos,
+				iov_iter_count(&iter));
+	if (!ret) {
+		/*
+		 * Open-code file_start_write here to grab freeze protection,
+		 * which will be released by another thread in
+		 * io_complete_rw().  Fool lockdep by telling it the lock got
+		 * released so that it doesn't complain about the held lock when
+		 * we return to userspace.
+		 */
+		if (S_ISREG(file_inode(file)->i_mode)) {
+			__sb_start_write(file_inode(file)->i_sb,
+						SB_FREEZE_WRITE, true);
+			__sb_writers_release(file_inode(file)->i_sb,
+						SB_FREEZE_WRITE);
+		}
+		kiocb->ki_flags |= IOCB_WRITE;
+		io_rw_done(kiocb, call_write_iter(file, kiocb, &iter));
+	}
+	kfree(iovec);
+out_fput:
+	if (unlikely(ret))
+		fput(file);
+	return ret;
+}
+
+/*
+ * IORING_OP_NOP just posts a completion event, nothing else.
+ */
+static int io_nop(struct io_kiocb *req, u64 user_data)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	io_cqring_add_event(ctx, user_data, 0, 0);
+	io_free_req(req);
+	return 0;
+}
+
+static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
+			   const struct sqe_submit *s, bool force_nonblock)
+{
+	ssize_t ret;
+	int opcode;
+
+	if (unlikely(s->index >= ctx->sq_entries))
+		return -EINVAL;
+	req->user_data = READ_ONCE(s->sqe->user_data);
+
+	opcode = READ_ONCE(s->sqe->opcode);
+	switch (opcode) {
+	case IORING_OP_NOP:
+		ret = io_nop(req, req->user_data);
+		break;
+	case IORING_OP_READV:
+		ret = io_read(req, s, force_nonblock);
+		break;
+	case IORING_OP_WRITEV:
+		ret = io_write(req, s, force_nonblock);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	return ret;
+}
+
+static void io_sq_wq_submit_work(struct work_struct *work)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+	struct sqe_submit *s = &req->submit;
+	u64 user_data = READ_ONCE(s->sqe->user_data);
+	struct io_ring_ctx *ctx = req->ctx;
+	mm_segment_t old_fs = get_fs();
+	int ret;
+
+	 /* Ensure we clear previously set forced non-block flag */
+	req->flags &= ~REQ_F_FORCE_NONBLOCK;
+	req->rw.ki_flags &= ~IOCB_NOWAIT;
+
+	if (!mmget_not_zero(ctx->sqo_mm)) {
+		ret = -EFAULT;
+		goto err;
+	}
+
+	use_mm(ctx->sqo_mm);
+	set_fs(USER_DS);
+	s->has_user = true;
+
+	ret = __io_submit_sqe(ctx, req, s, false);
+
+	set_fs(old_fs);
+	unuse_mm(ctx->sqo_mm);
+	mmput(ctx->sqo_mm);
+err:
+	if (ret) {
+		io_cqring_add_event(ctx, user_data, ret, 0);
+		io_free_req(req);
+	}
+}
+
+static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s)
+{
+	struct io_kiocb *req;
+	ssize_t ret;
+
+	/* enforce forwards compatibility on users */
+	if (unlikely(s->sqe->flags))
+		return -EINVAL;
+
+	req = io_get_req(ctx);
+	if (unlikely(!req))
+		return -EAGAIN;
+
+	req->rw.ki_filp = NULL;
+
+	ret = __io_submit_sqe(ctx, req, s, true);
+	if (ret == -EAGAIN) {
+		memcpy(&req->submit, s, sizeof(*s));
+		INIT_WORK(&req->work, io_sq_wq_submit_work);
+		queue_work(ctx->sqo_wq, &req->work);
+		ret = 0;
+	}
+	if (ret)
+		io_free_req(req);
+
+	return ret;
+}
+
+static void io_commit_sqring(struct io_ring_ctx *ctx)
+{
+	struct io_sq_ring *ring = ctx->sq_ring;
+
+	if (ctx->cached_sq_head != ring->r.head) {
+		WRITE_ONCE(ring->r.head, ctx->cached_sq_head);
+		/* write side barrier of head update, app has read side */
+		smp_wmb();
+	}
+}
+
+/*
+ * Undo last io_get_sqring()
+ */
+static void io_drop_sqring(struct io_ring_ctx *ctx)
+{
+	ctx->cached_sq_head--;
+}
+
+/*
+ * Fetch an sqe, if one is available. Note that s->sqe will point to memory
+ * that is mapped by userspace. This means that care needs to be taken to
+ * ensure that reads are stable, as we cannot rely on userspace always
+ * being a good citizen. If members of the sqe are validated and then later
+ * used, it's important that those reads are done through READ_ONCE() to
+ * prevent a re-load down the line.
+ */
+static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
+{
+	struct io_sq_ring *ring = ctx->sq_ring;
+	unsigned head;
+
+	/*
+	 * The cached sq head (or cq tail) serves two purposes:
+	 *
+	 * 1) allows us to batch the cost of updating the user visible
+	 *    head updates.
+	 * 2) allows the kernel side to track the head on its own, even
+	 *    though the application is the one updating it.
+	 */
+	head = ctx->cached_sq_head;
+	smp_rmb();
+	if (head == READ_ONCE(ring->r.tail))
+		return false;
+
+	head = READ_ONCE(ring->array[head & ctx->sq_mask]);
+	if (head < ctx->sq_entries) {
+		s->index = head;
+		s->sqe = &ctx->sq_sqes[head];
+		ctx->cached_sq_head++;
+		return true;
+	}
+
+	/* drop invalid entries */
+	ctx->cached_sq_head++;
+	ring->dropped++;
+	smp_wmb();
+	return false;
+}
+
+static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
+{
+	int i, ret = 0, submit = 0;
+	struct blk_plug plug;
+
+	if (to_submit > IO_PLUG_THRESHOLD)
+		blk_start_plug(&plug);
+
+	for (i = 0; i < to_submit; i++) {
+		struct sqe_submit s;
+
+		if (!io_get_sqring(ctx, &s))
+			break;
+
+		s.has_user = true;
+		ret = io_submit_sqe(ctx, &s);
+		if (ret) {
+			io_drop_sqring(ctx);
+			break;
+		}
+
+		submit++;
+	}
+	io_commit_sqring(ctx);
+
+	if (to_submit > IO_PLUG_THRESHOLD)
+		blk_finish_plug(&plug);
+
+	return submit ? submit : ret;
+}
+
+/*
+ * Wait until events become available, if we don't already have some. The
+ * application must reap them itself, as they reside on the shared cq ring.
+ */
+static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
+			  const sigset_t __user *sig, size_t sigsz)
+{
+	struct io_cq_ring *ring = ctx->cq_ring;
+	sigset_t ksigmask, sigsaved;
+	DEFINE_WAIT(wait);
+	int ret = 0;
+
+	smp_rmb();
+	if (ring->r.head != ring->r.tail)
+		return 0;
+	if (!min_events)
+		return 0;
+
+	if (sig) {
+		ret = set_user_sigmask(sig, &ksigmask, &sigsaved, sigsz);
+		if (ret)
+			return ret;
+	}
+
+	do {
+		prepare_to_wait(&ctx->wait, &wait, TASK_INTERRUPTIBLE);
+
+		ret = 0;
+		smp_rmb();
+		if (ring->r.head != ring->r.tail)
+			break;
+
+		schedule();
+
+		ret = -EINTR;
+		if (signal_pending(current))
+			break;
+	} while (1);
+
+	finish_wait(&ctx->wait, &wait);
+
+	if (sig)
+		restore_user_sigmask(sig, &sigsaved);
+
+	return ring->r.head == ring->r.tail ? ret : 0;
+}
+
+static int io_sq_offload_start(struct io_ring_ctx *ctx)
+{
+	int ret;
+
+	mmgrab(current->mm);
+	ctx->sqo_mm = current->mm;
+
+	/* Do QD, or 2 * CPUS, whatever is smallest */
+	ctx->sqo_wq = alloc_workqueue("io_ring-wq", WQ_UNBOUND | WQ_FREEZABLE,
+			min(ctx->sq_entries - 1, 2 * num_online_cpus()));
+	if (!ctx->sqo_wq) {
+		ret = -ENOMEM;
+		goto err;
+	}
+
+	return 0;
+err:
+	mmdrop(ctx->sqo_mm);
+	ctx->sqo_mm = NULL;
+	return ret;
+}
+
+static void io_unaccount_mem(struct user_struct *user, unsigned long nr_pages)
+{
+	if (capable(CAP_IPC_LOCK))
+		return;
+	atomic_long_sub(nr_pages, &user->locked_vm);
+}
+
+static int io_account_mem(struct user_struct *user, unsigned long nr_pages)
+{
+	unsigned long page_limit, cur_pages, new_pages;
+
+	if (capable(CAP_IPC_LOCK))
+		return 0;
+
+	/* Don't allow more pages than we can safely lock */
+	page_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
+
+	do {
+		cur_pages = atomic_long_read(&user->locked_vm);
+		new_pages = cur_pages + nr_pages;
+		if (new_pages > page_limit)
+			return -ENOMEM;
+	} while (atomic_long_cmpxchg(&user->locked_vm, cur_pages,
+					new_pages) != cur_pages);
+
+	return 0;
+}
+
+static void io_mem_free(void *ptr)
+{
+	struct page *page = virt_to_head_page(ptr);
+
+	if (put_page_testzero(page))
+		free_compound_page(page);
+}
+
+static void *io_mem_alloc(size_t size)
+{
+	gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP |
+				__GFP_NORETRY;
+
+	return (void *) __get_free_pages(gfp_flags, get_order(size));
+}
+
+static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries)
+{
+	struct io_sq_ring *sq_ring;
+	struct io_cq_ring *cq_ring;
+	size_t bytes;
+
+	bytes = struct_size(sq_ring, array, sq_entries);
+	bytes += array_size(sizeof(struct io_uring_sqe), sq_entries);
+	bytes += struct_size(cq_ring, cqes, cq_entries);
+
+	return (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
+}
+
+static void io_ring_ctx_free(struct io_ring_ctx *ctx)
+{
+	if (ctx->sqo_wq)
+		destroy_workqueue(ctx->sqo_wq);
+	if (ctx->sqo_mm)
+		mmdrop(ctx->sqo_mm);
+#if defined(CONFIG_NET)
+	if (ctx->ring_sock)
+		sock_release(ctx->ring_sock);
+#endif
+
+	io_mem_free(ctx->sq_ring);
+	io_mem_free(ctx->sq_sqes);
+	io_mem_free(ctx->cq_ring);
+
+	percpu_ref_exit(&ctx->refs);
+	io_unaccount_mem(ctx->user,
+				ring_pages(ctx->sq_entries, ctx->cq_entries));
+	free_uid(ctx->user);
+	kfree(ctx);
+}
+
+static __poll_t io_uring_poll(struct file *file, poll_table *wait)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+	__poll_t mask = 0;
+
+	poll_wait(file, &ctx->cq_wait, wait);
+	smp_rmb();
+	if (ctx->sq_ring->r.tail + 1 != ctx->cached_sq_head)
+		mask |= EPOLLOUT | EPOLLWRNORM;
+	if (ctx->cq_ring->r.head != ctx->cached_cq_tail)
+		mask |= EPOLLIN | EPOLLRDNORM;
+
+	return mask;
+}
+
+static int io_uring_fasync(int fd, struct file *file, int on)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+
+	return fasync_helper(fd, file, on, &ctx->cq_fasync);
+}
+
+static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
+{
+	mutex_lock(&ctx->uring_lock);
+	percpu_ref_kill(&ctx->refs);
+	mutex_unlock(&ctx->uring_lock);
+
+	wait_for_completion(&ctx->ctx_done);
+	io_ring_ctx_free(ctx);
+}
+
+static int io_uring_release(struct inode *inode, struct file *file)
+{
+	struct io_ring_ctx *ctx = file->private_data;
+
+	file->private_data = NULL;
+	io_ring_ctx_wait_and_kill(ctx);
+	return 0;
+}
+
+static int io_uring_mmap(struct file *file, struct vm_area_struct *vma)
+{
+	loff_t offset = (loff_t) vma->vm_pgoff << PAGE_SHIFT;
+	unsigned long sz = vma->vm_end - vma->vm_start;
+	struct io_ring_ctx *ctx = file->private_data;
+	unsigned long pfn;
+	struct page *page;
+	void *ptr;
+
+	switch (offset) {
+	case IORING_OFF_SQ_RING:
+		ptr = ctx->sq_ring;
+		break;
+	case IORING_OFF_SQES:
+		ptr = ctx->sq_sqes;
+		break;
+	case IORING_OFF_CQ_RING:
+		ptr = ctx->cq_ring;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	page = virt_to_head_page(ptr);
+	if (sz > (PAGE_SIZE << compound_order(page)))
+		return -EINVAL;
+
+	pfn = virt_to_phys(ptr) >> PAGE_SHIFT;
+	return remap_pfn_range(vma, vma->vm_start, pfn, sz, vma->vm_page_prot);
+}
+
+SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
+		u32, min_complete, u32, flags, const sigset_t __user *, sig,
+		size_t, sigsz)
+{
+	struct io_ring_ctx *ctx;
+	long ret = -EBADF;
+	int submitted = 0;
+	struct fd f;
+
+	if (flags & ~IORING_ENTER_GETEVENTS)
+		return -EINVAL;
+
+	f = fdget(fd);
+	if (!f.file)
+		return -EBADF;
+
+	ret = -EOPNOTSUPP;
+	if (f.file->f_op != &io_uring_fops)
+		goto out_fput;
+
+	ret = -ENXIO;
+	ctx = f.file->private_data;
+	if (!percpu_ref_tryget(&ctx->refs))
+		goto out_fput;
+
+	if (to_submit) {
+		to_submit = min(to_submit, ctx->sq_entries);
+
+		mutex_lock(&ctx->uring_lock);
+		submitted = io_ring_submit(ctx, to_submit);
+		mutex_unlock(&ctx->uring_lock);
+
+		if (submitted < 0)
+			goto out_ctx;
+	}
+	if (flags & IORING_ENTER_GETEVENTS) {
+		/*
+		 * The application could have included the 'to_submit' count
+		 * in how many events it wanted to wait for. If we failed to
+		 * submit the desired count, we may need to adjust the number
+		 * of events to poll/wait for.
+		 */
+		if (submitted < to_submit)
+			min_complete = min_t(unsigned, submitted, min_complete);
+
+		ret = io_cqring_wait(ctx, min_complete, sig, sigsz);
+	}
+
+out_ctx:
+	io_ring_drop_ctx_refs(ctx, 1);
+out_fput:
+	fdput(f);
+	return submitted ? submitted : ret;
+}
+
+static const struct file_operations io_uring_fops = {
+	.release	= io_uring_release,
+	.mmap		= io_uring_mmap,
+	.poll		= io_uring_poll,
+	.fasync		= io_uring_fasync,
+};
+
+static int io_allocate_scq_urings(struct io_ring_ctx *ctx,
+				  struct io_uring_params *p)
+{
+	struct io_sq_ring *sq_ring;
+	struct io_cq_ring *cq_ring;
+	size_t size;
+
+	sq_ring = io_mem_alloc(struct_size(sq_ring, array, p->sq_entries));
+	if (!sq_ring)
+		return -ENOMEM;
+
+	ctx->sq_ring = sq_ring;
+	sq_ring->ring_mask = p->sq_entries - 1;
+	sq_ring->ring_entries = p->sq_entries;
+	ctx->sq_mask = sq_ring->ring_mask;
+	ctx->sq_entries = sq_ring->ring_entries;
+
+	size = array_size(sizeof(struct io_uring_sqe), p->sq_entries);
+	if (size == SIZE_MAX)
+		return -EOVERFLOW;
+
+	ctx->sq_sqes = io_mem_alloc(size);
+	if (!ctx->sq_sqes) {
+		io_mem_free(ctx->sq_ring);
+		return -ENOMEM;
+	}
+
+	cq_ring = io_mem_alloc(struct_size(cq_ring, cqes, p->cq_entries));
+	if (!cq_ring) {
+		io_mem_free(ctx->sq_ring);
+		io_mem_free(ctx->sq_sqes);
+		return -ENOMEM;
+	}
+
+	ctx->cq_ring = cq_ring;
+	cq_ring->ring_mask = p->cq_entries - 1;
+	cq_ring->ring_entries = p->cq_entries;
+	ctx->cq_mask = cq_ring->ring_mask;
+	ctx->cq_entries = cq_ring->ring_entries;
+	return 0;
+}
+
+static int io_uring_get_fd(struct io_ring_ctx *ctx)
+{
+	struct file *file;
+	int ret;
+
+#if defined(CONFIG_NET)
+	ret = sock_create_kern(&init_net, PF_UNIX, SOCK_RAW, IPPROTO_IP,
+				&ctx->ring_sock);
+	if (ret)
+		return ret;
+#endif
+
+	ret = get_unused_fd_flags(O_RDWR | O_CLOEXEC);
+	if (ret < 0)
+		goto err;
+
+	file = anon_inode_getfile("[io_uring]", &io_uring_fops, ctx,
+					O_RDWR | O_CLOEXEC);
+	if (IS_ERR(file)) {
+		put_unused_fd(ret);
+		ret = PTR_ERR(file);
+		goto err;
+	}
+
+#if defined(CONFIG_NET)
+	ctx->ring_sock->file = file;
+#endif
+	fd_install(ret, file);
+	return ret;
+err:
+#if defined(CONFIG_NET)
+	sock_release(ctx->ring_sock);
+	ctx->ring_sock = NULL;
+#endif
+	return ret;
+}
+
+static int io_uring_create(unsigned entries, struct io_uring_params *p)
+{
+	struct user_struct *user = NULL;
+	struct io_ring_ctx *ctx;
+	int ret;
+
+	if (!entries || entries > IORING_MAX_ENTRIES)
+		return -EINVAL;
+
+	/*
+	 * Use twice as many entries for the CQ ring. It's possible for the
+	 * application to drive a higher depth than the size of the SQ ring,
+	 * since the sqes are only used at submission time. This allows for
+	 * some flexibility in overcommitting a bit.
+	 */
+	p->sq_entries = roundup_pow_of_two(entries);
+	p->cq_entries = 2 * p->sq_entries;
+
+	user = get_uid(current_user());
+	ret = io_account_mem(user, ring_pages(p->sq_entries, p->cq_entries));
+	if (ret) {
+		free_uid(user);
+		return ret;
+	}
+
+	ctx = io_ring_ctx_alloc(p);
+	if (!ctx) {
+		io_unaccount_mem(user, ring_pages(p->sq_entries,
+							p->cq_entries));
+		free_uid(user);
+		return -ENOMEM;
+	}
+	ctx->compat = in_compat_syscall();
+	ctx->user = user;
+
+	ret = io_allocate_scq_urings(ctx, p);
+	if (ret)
+		goto err;
+
+	ret = io_sq_offload_start(ctx);
+	if (ret)
+		goto err;
+
+	ret = io_uring_get_fd(ctx);
+	if (ret < 0)
+		goto err;
+
+	memset(&p->sq_off, 0, sizeof(p->sq_off));
+	p->sq_off.head = offsetof(struct io_sq_ring, r.head);
+	p->sq_off.tail = offsetof(struct io_sq_ring, r.tail);
+	p->sq_off.ring_mask = offsetof(struct io_sq_ring, ring_mask);
+	p->sq_off.ring_entries = offsetof(struct io_sq_ring, ring_entries);
+	p->sq_off.flags = offsetof(struct io_sq_ring, flags);
+	p->sq_off.dropped = offsetof(struct io_sq_ring, dropped);
+	p->sq_off.array = offsetof(struct io_sq_ring, array);
+
+	memset(&p->cq_off, 0, sizeof(p->cq_off));
+	p->cq_off.head = offsetof(struct io_cq_ring, r.head);
+	p->cq_off.tail = offsetof(struct io_cq_ring, r.tail);
+	p->cq_off.ring_mask = offsetof(struct io_cq_ring, ring_mask);
+	p->cq_off.ring_entries = offsetof(struct io_cq_ring, ring_entries);
+	p->cq_off.overflow = offsetof(struct io_cq_ring, overflow);
+	p->cq_off.cqes = offsetof(struct io_cq_ring, cqes);
+	return ret;
+err:
+	io_ring_ctx_wait_and_kill(ctx);
+	return ret;
+}
+
+/*
+ * Sets up an aio uring context, and returns the fd. Applications asks for a
+ * ring size, we return the actual sq/cq ring sizes (among other things) in the
+ * params structure passed in.
+ */
+static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
+{
+	struct io_uring_params p;
+	long ret;
+	int i;
+
+	if (copy_from_user(&p, params, sizeof(p)))
+		return -EFAULT;
+	for (i = 0; i < ARRAY_SIZE(p.resv); i++) {
+		if (p.resv[i])
+			return -EINVAL;
+	}
+
+	if (p.flags)
+		return -EINVAL;
+
+	ret = io_uring_create(entries, &p);
+	if (ret < 0)
+		return ret;
+
+	if (copy_to_user(params, &p, sizeof(p)))
+		return -EFAULT;
+
+	return ret;
+}
+
+SYSCALL_DEFINE2(io_uring_setup, u32, entries,
+		struct io_uring_params __user *, params)
+{
+	return io_uring_setup(entries, params);
+}
+
+static int __init io_uring_init(void)
+{
+	req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
+	return 0;
+};
+__initcall(io_uring_init);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index dedcc2e9265c..61aa210f0c2b 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -3517,4 +3517,13 @@ extern void inode_nohighmem(struct inode *inode);
 extern int vfs_fadvise(struct file *file, loff_t offset, loff_t len,
 		       int advice);
 
+#if defined(CONFIG_IO_URING)
+extern struct sock *io_uring_get_socket(struct file *file);
+#else
+static inline struct sock *io_uring_get_socket(struct file *file)
+{
+	return NULL;
+}
+#endif
+
 #endif /* _LINUX_FS_H */
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 257cccba3062..3072dbaa7869 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -69,6 +69,7 @@ struct file_handle;
 struct sigaltstack;
 struct rseq;
 union bpf_attr;
+struct io_uring_params;
 
 #include <linux/types.h>
 #include <linux/aio_abi.h>
@@ -309,6 +310,11 @@ asmlinkage long sys_io_pgetevents_time32(aio_context_t ctx_id,
 				struct io_event __user *events,
 				struct old_timespec32 __user *timeout,
 				const struct __aio_sigset *sig);
+asmlinkage long sys_io_uring_setup(u32 entries,
+				struct io_uring_params __user *p);
+asmlinkage long sys_io_uring_enter(unsigned int fd, u32 to_submit,
+				u32 min_complete, u32 flags,
+				const sigset_t __user *sig, size_t sigsz);
 
 /* fs/xattr.c */
 asmlinkage long sys_setxattr(const char __user *path, const char __user *name,
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index d90127298f12..87871e7b7ea7 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -740,9 +740,13 @@ __SC_COMP(__NR_io_pgetevents, sys_io_pgetevents, compat_sys_io_pgetevents)
 __SYSCALL(__NR_rseq, sys_rseq)
 #define __NR_kexec_file_load 294
 __SYSCALL(__NR_kexec_file_load,     sys_kexec_file_load)
+#define __NR_io_uring_setup 425
+__SYSCALL(__NR_io_uring_setup, sys_io_uring_setup)
+#define __NR_io_uring_enter 426
+__SYSCALL(__NR_io_uring_enter, sys_io_uring_enter)
 
 #undef __NR_syscalls
-#define __NR_syscalls 295
+#define __NR_syscalls 427
 
 /*
  * 32 bit systems traditionally used different
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
new file mode 100644
index 000000000000..ac692823d6f4
--- /dev/null
+++ b/include/uapi/linux/io_uring.h
@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Header file for the io_uring interface.
+ *
+ * Copyright (C) 2019 Jens Axboe
+ * Copyright (C) 2019 Christoph Hellwig
+ */
+#ifndef LINUX_IO_URING_H
+#define LINUX_IO_URING_H
+
+#include <linux/fs.h>
+#include <linux/types.h>
+
+/*
+ * IO submission data structure (Submission Queue Entry)
+ */
+struct io_uring_sqe {
+	__u8	opcode;		/* type of operation for this sqe */
+	__u8	flags;		/* as of now unused */
+	__u16	ioprio;		/* ioprio for the request */
+	__s32	fd;		/* file descriptor to do IO on */
+	__u64	off;		/* offset into file */
+	__u64	addr;		/* pointer to buffer or iovecs */
+	__u32	len;		/* buffer size or number of iovecs */
+	union {
+		__kernel_rwf_t	rw_flags;
+		__u32		__resv;
+	};
+	__u64	user_data;	/* data to be passed back at completion time */
+	__u64	__pad2[3];
+};
+
+#define IORING_OP_NOP		0
+#define IORING_OP_READV		1
+#define IORING_OP_WRITEV	2
+
+/*
+ * IO completion data structure (Completion Queue Entry)
+ */
+struct io_uring_cqe {
+	__u64	user_data;	/* sqe->data submission passed back */
+	__s32	res;		/* result code for this event */
+	__u32	flags;
+};
+
+/*
+ * Magic offsets for the application to mmap the data it needs
+ */
+#define IORING_OFF_SQ_RING		0ULL
+#define IORING_OFF_CQ_RING		0x8000000ULL
+#define IORING_OFF_SQES			0x10000000ULL
+
+/*
+ * Filled with the offset for mmap(2)
+ */
+struct io_sqring_offsets {
+	__u32 head;
+	__u32 tail;
+	__u32 ring_mask;
+	__u32 ring_entries;
+	__u32 flags;
+	__u32 dropped;
+	__u32 array;
+	__u32 resv1;
+	__u64 resv2;
+};
+
+struct io_cqring_offsets {
+	__u32 head;
+	__u32 tail;
+	__u32 ring_mask;
+	__u32 ring_entries;
+	__u32 overflow;
+	__u32 cqes;
+	__u64 resv[2];
+};
+
+/*
+ * io_uring_enter(2) flags
+ */
+#define IORING_ENTER_GETEVENTS	(1U << 0)
+
+/*
+ * Passed in for io_uring_setup(2). Copied back with updated info on success
+ */
+struct io_uring_params {
+	__u32 sq_entries;
+	__u32 cq_entries;
+	__u32 flags;
+	__u32 resv[7];
+	struct io_sqring_offsets sq_off;
+	struct io_cqring_offsets cq_off;
+};
+
+#endif
diff --git a/init/Kconfig b/init/Kconfig
index c9386a365eea..8b5e0da04384 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1414,6 +1414,15 @@ config AIO
 	  by some high performance threaded applications. Disabling
 	  this option saves about 7k.
 
+config IO_URING
+	bool "Enable IO uring support" if EXPERT
+	select ANON_INODES
+	default y
+	help
+	  This option enables support for the io_uring interface, enabling
+	  applications to submit and completion IO through submission and
+	  completion rings that are shared between the kernel and application.
+
 config ADVISE_SYSCALLS
 	bool "Enable madvise/fadvise syscalls" if EXPERT
 	default y
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index ab9d0e3c6d50..ee5e523564bb 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -46,6 +46,8 @@ COND_SYSCALL(io_getevents);
 COND_SYSCALL(io_pgetevents);
 COND_SYSCALL_COMPAT(io_getevents);
 COND_SYSCALL_COMPAT(io_pgetevents);
+COND_SYSCALL(io_uring_setup);
+COND_SYSCALL(io_uring_enter);
 
 /* fs/xattr.c */
 
diff --git a/net/unix/garbage.c b/net/unix/garbage.c
index c36757e72844..f81854d74c7d 100644
--- a/net/unix/garbage.c
+++ b/net/unix/garbage.c
@@ -108,6 +108,9 @@ struct sock *unix_get_socket(struct file *filp)
 		/* PF_UNIX ? */
 		if (s && sock->ops && sock->ops->family == PF_UNIX)
 			u_sock = s;
+	} else {
+		/* Could be an io_uring instance */
+		u_sock = io_uring_get_socket(filp);
 	}
 	return u_sock;
 }
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 06/18] io_uring: add fsync support
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (4 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 05/18] Add io_uring IO interface Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 07/18] io_uring: support for IO polling Jens Axboe
                   ` (11 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Add a new fsync opcode, which either syncs a range if one is passed,
or the whole file if the offset and length fields are both cleared
to zero.  A flag is provided to use fdatasync semantics, that is only
force out metadata which is required to retrieve the file data, but
not others like metadata.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c                 | 40 +++++++++++++++++++++++++++++++++++
 include/uapi/linux/io_uring.h |  8 ++++++-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 39a6cd14f0ec..e92ae7abffce 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -4,6 +4,7 @@
  * supporting fast/efficient IO.
  *
  * Copyright (C) 2018-2019 Jens Axboe
+ * Copyright (c) 2018-2019 Christoph Hellwig
  */
 #include <linux/kernel.h>
 #include <linux/init.h>
@@ -517,6 +518,42 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
 	return 0;
 }
 
+static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+		    bool force_nonblock)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	loff_t sqe_off = READ_ONCE(sqe->off);
+	loff_t sqe_len = READ_ONCE(sqe->len);
+	loff_t end = sqe_off + sqe_len;
+	unsigned fsync_flags;
+	struct file *file;
+	int ret, fd;
+
+	/* fsync always requires a blocking context */
+	if (force_nonblock)
+		return -EAGAIN;
+
+	if (unlikely(sqe->addr || sqe->ioprio))
+		return -EINVAL;
+
+	fsync_flags = READ_ONCE(sqe->fsync_flags);
+	if (unlikely(fsync_flags & ~IORING_FSYNC_DATASYNC))
+		return -EINVAL;
+
+	fd = READ_ONCE(sqe->fd);
+	file = fget(fd);
+	if (unlikely(!file))
+		return -EBADF;
+
+	ret = vfs_fsync_range(file, sqe_off, end > 0 ? end : LLONG_MAX,
+				fsync_flags & IORING_FSYNC_DATASYNC);
+
+	fput(file);
+	io_cqring_add_event(ctx, sqe->user_data, ret, 0);
+	io_free_req(req);
+	return 0;
+}
+
 static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 			   const struct sqe_submit *s, bool force_nonblock)
 {
@@ -538,6 +575,9 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	case IORING_OP_WRITEV:
 		ret = io_write(req, s, force_nonblock);
 		break;
+	case IORING_OP_FSYNC:
+		ret = io_fsync(req, s->sqe, force_nonblock);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index ac692823d6f4..4589d56d0b68 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -24,7 +24,7 @@ struct io_uring_sqe {
 	__u32	len;		/* buffer size or number of iovecs */
 	union {
 		__kernel_rwf_t	rw_flags;
-		__u32		__resv;
+		__u32		fsync_flags;
 	};
 	__u64	user_data;	/* data to be passed back at completion time */
 	__u64	__pad2[3];
@@ -33,6 +33,12 @@ struct io_uring_sqe {
 #define IORING_OP_NOP		0
 #define IORING_OP_READV		1
 #define IORING_OP_WRITEV	2
+#define IORING_OP_FSYNC		3
+
+/*
+ * sqe->fsync_flags
+ */
+#define IORING_FSYNC_DATASYNC	(1U << 0)
 
 /*
  * IO completion data structure (Completion Queue Entry)
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 07/18] io_uring: support for IO polling
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (5 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 06/18] io_uring: add fsync support Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 08/18] fs: add fget_many() and fput_many() Jens Axboe
                   ` (10 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

Add support for a polled io_uring context. When a read or write is
submitted to a polled context, the application must poll for completions
on the CQ ring through io_uring_enter(2). Polled IO may not generate
IRQ completions, hence they need to be actively found by the application
itself.

To use polling, io_uring_setup() must be used with the
IORING_SETUP_IOPOLL flag being set. It is illegal to mix and match
polled and non-polled IO on an io_uring.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c                 | 274 ++++++++++++++++++++++++++++++++--
 include/uapi/linux/io_uring.h |   5 +
 2 files changed, 270 insertions(+), 9 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e92ae7abffce..5e83391dc538 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -103,6 +103,14 @@ struct io_ring_ctx {
 
 	struct {
 		spinlock_t		completion_lock;
+		bool			poll_multi_file;
+		/*
+		 * ->poll_list is protected by the ctx->uring_lock for
+		 * io_uring instances that don't use IORING_SETUP_SQPOLL.
+		 * For SQPOLL, only the single threaded io_sq_thread() will
+		 * manipulate the list, hence no extra locking is needed there.
+		 */
+		struct list_head	poll_list;
 	} ____cacheline_aligned_in_smp;
 
 #if defined(CONFIG_NET)
@@ -114,6 +122,7 @@ struct sqe_submit {
 	const struct io_uring_sqe	*sqe;
 	unsigned short			index;
 	bool				has_user;
+	bool				needs_lock;
 };
 
 struct io_kiocb {
@@ -125,12 +134,15 @@ struct io_kiocb {
 	struct list_head	list;
 	unsigned int		flags;
 #define REQ_F_FORCE_NONBLOCK	1	/* inline submission attempt */
+#define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
 	u64			user_data;
+	u64			error;
 
 	struct work_struct	work;
 };
 
 #define IO_PLUG_THRESHOLD		2
+#define IO_IOPOLL_BATCH			8
 
 static struct kmem_cache *req_cachep;
 
@@ -174,6 +186,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	mutex_init(&ctx->uring_lock);
 	init_waitqueue_head(&ctx->wait);
 	spin_lock_init(&ctx->completion_lock);
+	INIT_LIST_HEAD(&ctx->poll_list);
 	return ctx;
 }
 
@@ -268,12 +281,153 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx)
 	return NULL;
 }
 
+static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
+{
+	if (*nr) {
+		kmem_cache_free_bulk(req_cachep, *nr, reqs);
+		io_ring_drop_ctx_refs(ctx, *nr);
+		*nr = 0;
+	}
+}
+
 static void io_free_req(struct io_kiocb *req)
 {
 	io_ring_drop_ctx_refs(req->ctx, 1);
 	kmem_cache_free(req_cachep, req);
 }
 
+/*
+ * Find and free completed poll iocbs
+ */
+static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
+			       struct list_head *done)
+{
+	void *reqs[IO_IOPOLL_BATCH];
+	struct io_kiocb *req;
+	int to_free = 0;
+
+	while (!list_empty(done)) {
+		req = list_first_entry(done, struct io_kiocb, list);
+		list_del(&req->list);
+
+		io_cqring_fill_event(ctx, req->user_data, req->error, 0);
+
+		reqs[to_free++] = req;
+		(*nr_events)++;
+
+		fput(req->rw.ki_filp);
+		if (to_free == ARRAY_SIZE(reqs))
+			io_free_req_many(ctx, reqs, &to_free);
+	}
+	io_commit_cqring(ctx);
+
+	io_free_req_many(ctx, reqs, &to_free);
+}
+
+static int io_do_iopoll(struct io_ring_ctx *ctx, unsigned int *nr_events,
+			long min)
+{
+	struct io_kiocb *req, *tmp;
+	LIST_HEAD(done);
+	bool spin;
+	int ret;
+
+	/*
+	 * Only spin for completions if we don't have multiple devices hanging
+	 * off our complete list, and we're under the requested amount.
+	 */
+	spin = !ctx->poll_multi_file && *nr_events < min;
+
+	ret = 0;
+	list_for_each_entry_safe(req, tmp, &ctx->poll_list, list) {
+		struct kiocb *kiocb = &req->rw;
+
+		/*
+		 * Move completed entries to our local list. If we find a
+		 * request that requires polling, break out and complete
+		 * the done list first, if we have entries there.
+		 */
+		if (req->flags & REQ_F_IOPOLL_COMPLETED) {
+			list_move_tail(&req->list, &done);
+			continue;
+		}
+		if (!list_empty(&done))
+			break;
+
+		ret = kiocb->ki_filp->f_op->iopoll(kiocb, spin);
+		if (ret < 0)
+			break;
+
+		if (ret && spin)
+			spin = false;
+		ret = 0;
+	}
+
+	if (!list_empty(&done))
+		io_iopoll_complete(ctx, nr_events, &done);
+
+	return ret;
+}
+
+/*
+ * Poll for a mininum of 'min' events. Note that if min == 0 we consider that a
+ * non-spinning poll check - we'll still enter the driver poll loop, but only
+ * as a non-spinning completion check.
+ */
+static int io_iopoll_getevents(struct io_ring_ctx *ctx, unsigned int *nr_events,
+				long min)
+{
+	while (!list_empty(&ctx->poll_list)) {
+		int ret;
+
+		ret = io_do_iopoll(ctx, nr_events, min);
+		if (ret < 0)
+			return ret;
+		if (!min || *nr_events >= min)
+			return 0;
+	}
+
+	return 1;
+}
+
+/*
+ * We can't just wait for polled events to come to us, we have to actively
+ * find and complete them.
+ */
+static void io_iopoll_reap_events(struct io_ring_ctx *ctx)
+{
+	if (!(ctx->flags & IORING_SETUP_IOPOLL))
+		return;
+
+	mutex_lock(&ctx->uring_lock);
+	while (!list_empty(&ctx->poll_list)) {
+		unsigned int nr_events = 0;
+
+		io_iopoll_getevents(ctx, &nr_events, 1);
+	}
+	mutex_unlock(&ctx->uring_lock);
+}
+
+static int io_iopoll_check(struct io_ring_ctx *ctx, unsigned *nr_events,
+			   long min)
+{
+	int ret = 0;
+
+	do {
+		int tmin = 0;
+
+		if (*nr_events < min)
+			tmin = min - *nr_events;
+
+		ret = io_iopoll_getevents(ctx, nr_events, tmin);
+		if (ret <= 0)
+			break;
+		ret = 0;
+	} while (min && !*nr_events && !need_resched());
+
+	return ret;
+}
+
 static void kiocb_end_write(struct kiocb *kiocb)
 {
 	if (kiocb->ki_flags & IOCB_WRITE) {
@@ -300,6 +454,53 @@ static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
 	io_free_req(req);
 }
 
+static void io_complete_rw_iopoll(struct kiocb *kiocb, long res, long res2)
+{
+	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
+
+	kiocb_end_write(kiocb);
+
+	req->error = res;
+	if (res != -EAGAIN)
+		req->flags |= REQ_F_IOPOLL_COMPLETED;
+}
+
+/*
+ * After the iocb has been issued, it's safe to be found on the poll list.
+ * Adding the kiocb to the list AFTER submission ensures that we don't
+ * find it from a io_iopoll_getevents() thread before the issuer is done
+ * accessing the kiocb cookie.
+ */
+static void io_iopoll_req_issued(struct io_kiocb *req)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+
+	/*
+	 * Track whether we have multiple files in our lists. This will impact
+	 * how we do polling eventually, not spinning if we're on potentially
+	 * different devices.
+	 */
+	if (list_empty(&ctx->poll_list)) {
+		ctx->poll_multi_file = false;
+	} else if (!ctx->poll_multi_file) {
+		struct io_kiocb *list_req;
+
+		list_req = list_first_entry(&ctx->poll_list, struct io_kiocb,
+						list);
+		if (list_req->rw.ki_filp != req->rw.ki_filp)
+			ctx->poll_multi_file = true;
+	}
+
+	/*
+	 * For fast devices, IO may have already completed. If it has, add
+	 * it to the front so we find it first.
+	 */
+	if (req->flags & REQ_F_IOPOLL_COMPLETED)
+		list_add(&req->list, &ctx->poll_list);
+	else
+		list_add_tail(&req->list, &ctx->poll_list);
+}
+
 /*
  * If we tracked the file through the SCM inflight mechanism, we could support
  * any file. For now, just ensure that anything potentially problematic is done
@@ -320,6 +521,7 @@ static bool io_file_supports_async(struct file *file)
 static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		      bool force_nonblock)
 {
+	struct io_ring_ctx *ctx = req->ctx;
 	struct kiocb *kiocb = &req->rw;
 	unsigned ioprio;
 	int fd, ret;
@@ -355,12 +557,22 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		kiocb->ki_flags |= IOCB_NOWAIT;
 		req->flags |= REQ_F_FORCE_NONBLOCK;
 	}
-	if (kiocb->ki_flags & IOCB_HIPRI) {
-		ret = -EINVAL;
-		goto out_fput;
-	}
+	if (ctx->flags & IORING_SETUP_IOPOLL) {
+		ret = -EOPNOTSUPP;
+		if (!(kiocb->ki_flags & IOCB_DIRECT) ||
+		    !kiocb->ki_filp->f_op->iopoll)
+			goto out_fput;
 
-	kiocb->ki_complete = io_complete_rw;
+		req->error = 0;
+		kiocb->ki_flags |= IOCB_HIPRI;
+		kiocb->ki_complete = io_complete_rw_iopoll;
+	} else {
+		if (kiocb->ki_flags & IOCB_HIPRI) {
+			ret = -EINVAL;
+			goto out_fput;
+		}
+		kiocb->ki_complete = io_complete_rw;
+	}
 	return 0;
 out_fput:
 	fput(kiocb->ki_filp);
@@ -513,6 +725,9 @@ static int io_nop(struct io_kiocb *req, u64 user_data)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 
+	if (unlikely(ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+
 	io_cqring_add_event(ctx, user_data, 0, 0);
 	io_free_req(req);
 	return 0;
@@ -533,6 +748,8 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	if (force_nonblock)
 		return -EAGAIN;
 
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
 	if (unlikely(sqe->addr || sqe->ioprio))
 		return -EINVAL;
 
@@ -583,7 +800,22 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		break;
 	}
 
-	return ret;
+	if (ret)
+		return ret;
+
+	if (ctx->flags & IORING_SETUP_IOPOLL) {
+		if (req->error == -EAGAIN)
+			return -EAGAIN;
+
+		/* workqueue context doesn't hold uring_lock, grab it now */
+		if (s->needs_lock)
+			mutex_lock(&ctx->uring_lock);
+		io_iopoll_req_issued(req);
+		if (s->needs_lock)
+			mutex_unlock(&ctx->uring_lock);
+	}
+
+	return 0;
 }
 
 static void io_sq_wq_submit_work(struct work_struct *work)
@@ -607,8 +839,19 @@ static void io_sq_wq_submit_work(struct work_struct *work)
 	use_mm(ctx->sqo_mm);
 	set_fs(USER_DS);
 	s->has_user = true;
+	s->needs_lock = true;
 
-	ret = __io_submit_sqe(ctx, req, s, false);
+	do {
+		ret = __io_submit_sqe(ctx, req, s, false);
+		/*
+		 * We can get EAGAIN for polled IO even though we're forcing
+		 * a sync submission from here, since we can't wait for
+		 * request slots on the block side.
+		 */
+		if (ret != -EAGAIN)
+			break;
+		cond_resched();
+	} while (1);
 
 	set_fs(old_fs);
 	unuse_mm(ctx->sqo_mm);
@@ -723,6 +966,8 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 			break;
 
 		s.has_user = true;
+		s.needs_lock = false;
+
 		ret = io_submit_sqe(ctx, &s);
 		if (ret) {
 			io_drop_sqring(ctx);
@@ -876,6 +1121,8 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 		sock_release(ctx->ring_sock);
 #endif
 
+	io_iopoll_reap_events(ctx);
+
 	io_mem_free(ctx->sq_ring);
 	io_mem_free(ctx->sq_sqes);
 	io_mem_free(ctx->cq_ring);
@@ -915,6 +1162,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 	percpu_ref_kill(&ctx->refs);
 	mutex_unlock(&ctx->uring_lock);
 
+	io_iopoll_reap_events(ctx);
 	wait_for_completion(&ctx->ctx_done);
 	io_ring_ctx_free(ctx);
 }
@@ -995,6 +1243,8 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 			goto out_ctx;
 	}
 	if (flags & IORING_ENTER_GETEVENTS) {
+		unsigned nr_events = 0;
+
 		/*
 		 * The application could have included the 'to_submit' count
 		 * in how many events it wanted to wait for. If we failed to
@@ -1004,7 +1254,13 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 		if (submitted < to_submit)
 			min_complete = min_t(unsigned, submitted, min_complete);
 
-		ret = io_cqring_wait(ctx, min_complete, sig, sigsz);
+		if (ctx->flags & IORING_SETUP_IOPOLL) {
+			mutex_lock(&ctx->uring_lock);
+			ret = io_iopoll_check(ctx, &nr_events, min_complete);
+			mutex_unlock(&ctx->uring_lock);
+		} else {
+			ret = io_cqring_wait(ctx, min_complete, sig, sigsz);
+		}
 	}
 
 out_ctx:
@@ -1187,7 +1443,7 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
 			return -EINVAL;
 	}
 
-	if (p.flags)
+	if (p.flags & ~IORING_SETUP_IOPOLL)
 		return -EINVAL;
 
 	ret = io_uring_create(entries, &p);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 4589d56d0b68..5c457ea396e6 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -30,6 +30,11 @@ struct io_uring_sqe {
 	__u64	__pad2[3];
 };
 
+/*
+ * io_uring_setup() flags
+ */
+#define IORING_SETUP_IOPOLL	(1U << 0)	/* io_context is polled */
+
 #define IORING_OP_NOP		0
 #define IORING_OP_READV		1
 #define IORING_OP_WRITEV	2
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 08/18] fs: add fget_many() and fput_many()
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (6 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 07/18] io_uring: support for IO polling Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 09/18] io_uring: use fget/fput_many() for file references Jens Axboe
                   ` (9 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

Some uses cases repeatedly get and put references to the same file, but
the only exposed interface is doing these one at the time. As each of
these entail an atomic inc or dec on a shared structure, that cost can
add up.

Add fget_many(), which works just like fget(), except it takes an
argument for how many references to get on the file. Ditto fput_many(),
which can drop an arbitrary number of references to a file.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/file.c            | 15 ++++++++++-----
 fs/file_table.c      |  9 +++++++--
 include/linux/file.h |  2 ++
 include/linux/fs.h   |  4 +++-
 4 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/fs/file.c b/fs/file.c
index 3209ee271c41..97df385d6ab0 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -705,7 +705,7 @@ void do_close_on_exec(struct files_struct *files)
 	spin_unlock(&files->file_lock);
 }
 
-static struct file *__fget(unsigned int fd, fmode_t mask)
+static struct file *__fget(unsigned int fd, fmode_t mask, unsigned int refs)
 {
 	struct files_struct *files = current->files;
 	struct file *file;
@@ -720,7 +720,7 @@ static struct file *__fget(unsigned int fd, fmode_t mask)
 		 */
 		if (file->f_mode & mask)
 			file = NULL;
-		else if (!get_file_rcu(file))
+		else if (!get_file_rcu_many(file, refs))
 			goto loop;
 	}
 	rcu_read_unlock();
@@ -728,15 +728,20 @@ static struct file *__fget(unsigned int fd, fmode_t mask)
 	return file;
 }
 
+struct file *fget_many(unsigned int fd, unsigned int refs)
+{
+	return __fget(fd, FMODE_PATH, refs);
+}
+
 struct file *fget(unsigned int fd)
 {
-	return __fget(fd, FMODE_PATH);
+	return __fget(fd, FMODE_PATH, 1);
 }
 EXPORT_SYMBOL(fget);
 
 struct file *fget_raw(unsigned int fd)
 {
-	return __fget(fd, 0);
+	return __fget(fd, 0, 1);
 }
 EXPORT_SYMBOL(fget_raw);
 
@@ -767,7 +772,7 @@ static unsigned long __fget_light(unsigned int fd, fmode_t mask)
 			return 0;
 		return (unsigned long)file;
 	} else {
-		file = __fget(fd, mask);
+		file = __fget(fd, mask, 1);
 		if (!file)
 			return 0;
 		return FDPUT_FPUT | (unsigned long)file;
diff --git a/fs/file_table.c b/fs/file_table.c
index 5679e7fcb6b0..155d7514a094 100644
--- a/fs/file_table.c
+++ b/fs/file_table.c
@@ -326,9 +326,9 @@ void flush_delayed_fput(void)
 
 static DECLARE_DELAYED_WORK(delayed_fput_work, delayed_fput);
 
-void fput(struct file *file)
+void fput_many(struct file *file, unsigned int refs)
 {
-	if (atomic_long_dec_and_test(&file->f_count)) {
+	if (atomic_long_sub_and_test(refs, &file->f_count)) {
 		struct task_struct *task = current;
 
 		if (likely(!in_interrupt() && !(task->flags & PF_KTHREAD))) {
@@ -347,6 +347,11 @@ void fput(struct file *file)
 	}
 }
 
+void fput(struct file *file)
+{
+	fput_many(file, 1);
+}
+
 /*
  * synchronous analog of fput(); for kernel threads that might be needed
  * in some umount() (and thus can't use flush_delayed_fput() without
diff --git a/include/linux/file.h b/include/linux/file.h
index 6b2fb032416c..3fcddff56bc4 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -13,6 +13,7 @@
 struct file;
 
 extern void fput(struct file *);
+extern void fput_many(struct file *, unsigned int);
 
 struct file_operations;
 struct vfsmount;
@@ -44,6 +45,7 @@ static inline void fdput(struct fd fd)
 }
 
 extern struct file *fget(unsigned int fd);
+extern struct file *fget_many(unsigned int fd, unsigned int refs);
 extern struct file *fget_raw(unsigned int fd);
 extern unsigned long __fdget(unsigned int fd);
 extern unsigned long __fdget_raw(unsigned int fd);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 61aa210f0c2b..80e1b199a4b1 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -952,7 +952,9 @@ static inline struct file *get_file(struct file *f)
 	atomic_long_inc(&f->f_count);
 	return f;
 }
-#define get_file_rcu(x) atomic_long_inc_not_zero(&(x)->f_count)
+#define get_file_rcu_many(x, cnt)	\
+	atomic_long_add_unless(&(x)->f_count, (cnt), 0)
+#define get_file_rcu(x) get_file_rcu_many((x), 1)
 #define fput_atomic(x)	atomic_long_add_unless(&(x)->f_count, -1, 1)
 #define file_count(x)	atomic_long_read(&(x)->f_count)
 
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 09/18] io_uring: use fget/fput_many() for file references
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (7 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 08/18] fs: add fget_many() and fput_many() Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 10/18] io_uring: batch io_kiocb allocation Jens Axboe
                   ` (8 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

Add a separate io_submit_state structure, to cache some of the things
we need for IO submission.

One such example is file reference batching. io_submit_state. We get as
many references as the number of sqes we are submitting, and drop
unused ones if we end up switching files. The assumption here is that
we're usually only dealing with one fd, and if there are multiple,
hopefuly they are at least somewhat ordered. Could trivially be extended
to cover multiple fds, if needed.

On the completion side we do the same thing, except this is trivially
done just locally in io_iopoll_reap().

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c | 142 ++++++++++++++++++++++++++++++++++++++++++--------
 1 file changed, 121 insertions(+), 21 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 5e83391dc538..e23e639a4ff0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -144,6 +144,19 @@ struct io_kiocb {
 #define IO_PLUG_THRESHOLD		2
 #define IO_IOPOLL_BATCH			8
 
+struct io_submit_state {
+	struct blk_plug plug;
+
+	/*
+	 * File reference cache
+	 */
+	struct file *file;
+	unsigned int fd;
+	unsigned int has_refs;
+	unsigned int used_refs;
+	unsigned int ios_left;
+};
+
 static struct kmem_cache *req_cachep;
 
 static const struct file_operations io_uring_fops;
@@ -303,9 +316,11 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 			       struct list_head *done)
 {
 	void *reqs[IO_IOPOLL_BATCH];
+	int file_count, to_free;
+	struct file *file = NULL;
 	struct io_kiocb *req;
-	int to_free = 0;
 
+	file_count = to_free = 0;
 	while (!list_empty(done)) {
 		req = list_first_entry(done, struct io_kiocb, list);
 		list_del(&req->list);
@@ -315,12 +330,28 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 		reqs[to_free++] = req;
 		(*nr_events)++;
 
-		fput(req->rw.ki_filp);
+		/*
+		 * Batched puts of the same file, to avoid dirtying the
+		 * file usage count multiple times, if avoidable.
+		 */
+		if (!file) {
+			file = req->rw.ki_filp;
+			file_count = 1;
+		} else if (file == req->rw.ki_filp) {
+			file_count++;
+		} else {
+			fput_many(file, file_count);
+			file = req->rw.ki_filp;
+			file_count = 1;
+		}
+
 		if (to_free == ARRAY_SIZE(reqs))
 			io_free_req_many(ctx, reqs, &to_free);
 	}
 	io_commit_cqring(ctx);
 
+	if (file)
+		fput_many(file, file_count);
 	io_free_req_many(ctx, reqs, &to_free);
 }
 
@@ -501,6 +532,48 @@ static void io_iopoll_req_issued(struct io_kiocb *req)
 		list_add_tail(&req->list, &ctx->poll_list);
 }
 
+static void io_file_put(struct io_submit_state *state, struct file *file)
+{
+	if (!state) {
+		fput(file);
+	} else if (state->file) {
+		int diff = state->has_refs - state->used_refs;
+
+		if (diff)
+			fput_many(state->file, diff);
+		state->file = NULL;
+	}
+}
+
+/*
+ * Get as many references to a file as we have IOs left in this submission,
+ * assuming most submissions are for one file, or at least that each file
+ * has more than one submission.
+ */
+static struct file *io_file_get(struct io_submit_state *state, int fd)
+{
+	if (!state)
+		return fget(fd);
+
+	if (state->file) {
+		if (state->fd == fd) {
+			state->used_refs++;
+			state->ios_left--;
+			return state->file;
+		}
+		io_file_put(state, NULL);
+	}
+	state->file = fget_many(fd, state->ios_left);
+	if (!state->file)
+		return NULL;
+
+	state->fd = fd;
+	state->has_refs = state->ios_left;
+	state->used_refs = 1;
+	state->ios_left--;
+	return state->file;
+}
+
 /*
  * If we tracked the file through the SCM inflight mechanism, we could support
  * any file. For now, just ensure that anything potentially problematic is done
@@ -519,7 +592,7 @@ static bool io_file_supports_async(struct file *file)
 }
 
 static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
-		      bool force_nonblock)
+		      bool force_nonblock, struct io_submit_state *state)
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct kiocb *kiocb = &req->rw;
@@ -531,7 +604,7 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		return 0;
 
 	fd = READ_ONCE(sqe->fd);
-	kiocb->ki_filp = fget(fd);
+	kiocb->ki_filp = io_file_get(state, fd);
 	if (unlikely(!kiocb->ki_filp))
 		return -EBADF;
 	if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
@@ -575,7 +648,10 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	}
 	return 0;
 out_fput:
-	fput(kiocb->ki_filp);
+	/* in case of error, we didn't use this file reference. drop it. */
+	if (state)
+		state->used_refs--;
+	io_file_put(state, kiocb->ki_filp);
 	return ret;
 }
 
@@ -621,7 +697,7 @@ static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
 }
 
 static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
-		       bool force_nonblock)
+		       bool force_nonblock, struct io_submit_state *state)
 {
 	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
 	struct kiocb *kiocb = &req->rw;
@@ -629,7 +705,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
 	struct file *file;
 	ssize_t ret;
 
-	ret = io_prep_rw(req, s->sqe, force_nonblock);
+	ret = io_prep_rw(req, s->sqe, force_nonblock, state);
 	if (ret)
 		return ret;
 	file = kiocb->ki_filp;
@@ -665,7 +741,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
 }
 
 static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
-			bool force_nonblock)
+			bool force_nonblock, struct io_submit_state *state)
 {
 	struct iovec inline_vecs[UIO_FASTIOV], *iovec = inline_vecs;
 	struct kiocb *kiocb = &req->rw;
@@ -673,7 +749,7 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
 	struct file *file;
 	ssize_t ret;
 
-	ret = io_prep_rw(req, s->sqe, force_nonblock);
+	ret = io_prep_rw(req, s->sqe, force_nonblock, state);
 	if (ret)
 		return ret;
 	/* Hold on to the file for -EAGAIN */
@@ -772,7 +848,8 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 }
 
 static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
-			   const struct sqe_submit *s, bool force_nonblock)
+			   const struct sqe_submit *s, bool force_nonblock,
+			   struct io_submit_state *state)
 {
 	ssize_t ret;
 	int opcode;
@@ -787,10 +864,10 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		ret = io_nop(req, req->user_data);
 		break;
 	case IORING_OP_READV:
-		ret = io_read(req, s, force_nonblock);
+		ret = io_read(req, s, force_nonblock, state);
 		break;
 	case IORING_OP_WRITEV:
-		ret = io_write(req, s, force_nonblock);
+		ret = io_write(req, s, force_nonblock, state);
 		break;
 	case IORING_OP_FSYNC:
 		ret = io_fsync(req, s->sqe, force_nonblock);
@@ -842,7 +919,7 @@ static void io_sq_wq_submit_work(struct work_struct *work)
 	s->needs_lock = true;
 
 	do {
-		ret = __io_submit_sqe(ctx, req, s, false);
+		ret = __io_submit_sqe(ctx, req, s, false, NULL);
 		/*
 		 * We can get EAGAIN for polled IO even though we're forcing
 		 * a sync submission from here, since we can't wait for
@@ -863,7 +940,8 @@ static void io_sq_wq_submit_work(struct work_struct *work)
 	}
 }
 
-static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s)
+static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s,
+			 struct io_submit_state *state)
 {
 	struct io_kiocb *req;
 	ssize_t ret;
@@ -878,7 +956,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s)
 
 	req->rw.ki_filp = NULL;
 
-	ret = __io_submit_sqe(ctx, req, s, true);
+	ret = __io_submit_sqe(ctx, req, s, true, state);
 	if (ret == -EAGAIN) {
 		memcpy(&req->submit, s, sizeof(*s));
 		INIT_WORK(&req->work, io_sq_wq_submit_work);
@@ -891,6 +969,26 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s)
 	return ret;
 }
 
+/*
+ * Batched submission is done, ensure local IO is flushed out.
+ */
+static void io_submit_state_end(struct io_submit_state *state)
+{
+	blk_finish_plug(&state->plug);
+	io_file_put(state, NULL);
+}
+
+/*
+ * Start submission side cache.
+ */
+static void io_submit_state_start(struct io_submit_state *state,
+				  struct io_ring_ctx *ctx, unsigned max_ios)
+{
+	blk_start_plug(&state->plug);
+	state->file = NULL;
+	state->ios_left = max_ios;
+}
+
 static void io_commit_sqring(struct io_ring_ctx *ctx)
 {
 	struct io_sq_ring *ring = ctx->sq_ring;
@@ -953,11 +1051,13 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
 
 static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 {
+	struct io_submit_state state, *statep = NULL;
 	int i, ret = 0, submit = 0;
-	struct blk_plug plug;
 
-	if (to_submit > IO_PLUG_THRESHOLD)
-		blk_start_plug(&plug);
+	if (to_submit > IO_PLUG_THRESHOLD) {
+		io_submit_state_start(&state, ctx, to_submit);
+		statep = &state;
+	}
 
 	for (i = 0; i < to_submit; i++) {
 		struct sqe_submit s;
@@ -968,7 +1068,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 		s.has_user = true;
 		s.needs_lock = false;
 
-		ret = io_submit_sqe(ctx, &s);
+		ret = io_submit_sqe(ctx, &s, statep);
 		if (ret) {
 			io_drop_sqring(ctx);
 			break;
@@ -978,8 +1078,8 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 	}
 	io_commit_sqring(ctx);
 
-	if (to_submit > IO_PLUG_THRESHOLD)
-		blk_finish_plug(&plug);
+	if (statep)
+		io_submit_state_end(statep);
 
 	return submit ? submit : ret;
 }
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 10/18] io_uring: batch io_kiocb allocation
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (8 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 09/18] io_uring: use fget/fput_many() for file references Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 11/18] block: implement bio helper to add iter bvec pages to bio Jens Axboe
                   ` (7 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

Similarly to how we use the state->ios_left to know how many references
to get to a file, we can use it to allocate the io_kiocb's we need in
bulk.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c | 45 ++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 38 insertions(+), 7 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e23e639a4ff0..1369cb95e1b5 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -147,6 +147,13 @@ struct io_kiocb {
 struct io_submit_state {
 	struct blk_plug plug;
 
+	/*
+	 * io_kiocb alloc cache
+	 */
+	void *reqs[IO_IOPOLL_BATCH];
+	unsigned int free_reqs;
+	unsigned int cur_req;
+
 	/*
 	 * File reference cache
 	 */
@@ -276,20 +283,40 @@ static void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs)
 		wake_up(&ctx->wait);
 }
 
-static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx)
+static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
+				   struct io_submit_state *state)
 {
 	struct io_kiocb *req;
 
 	if (!percpu_ref_tryget(&ctx->refs))
 		return NULL;
 
-	req = kmem_cache_alloc(req_cachep, __GFP_NOWARN);
-	if (req) {
-		req->ctx = ctx;
-		req->flags = 0;
-		return req;
+	if (!state) {
+		req = kmem_cache_alloc(req_cachep, __GFP_NOWARN);
+		if (unlikely(!req))
+			goto out;
+	} else if (!state->free_reqs) {
+		size_t sz;
+		int ret;
+
+		sz = min_t(size_t, state->ios_left, ARRAY_SIZE(state->reqs));
+		ret = kmem_cache_alloc_bulk(req_cachep, __GFP_NOWARN, sz,
+						state->reqs);
+		if (unlikely(ret <= 0))
+			goto out;
+		state->free_reqs = ret - 1;
+		state->cur_req = 1;
+		req = state->reqs[0];
+	} else {
+		req = state->reqs[state->cur_req];
+		state->free_reqs--;
+		state->cur_req++;
 	}
 
+	req->ctx = ctx;
+	req->flags = 0;
+	return req;
+out:
 	io_ring_drop_ctx_refs(ctx, 1);
 	return NULL;
 }
@@ -950,7 +977,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s,
 	if (unlikely(s->sqe->flags))
 		return -EINVAL;
 
-	req = io_get_req(ctx);
+	req = io_get_req(ctx, state);
 	if (unlikely(!req))
 		return -EAGAIN;
 
@@ -976,6 +1003,9 @@ static void io_submit_state_end(struct io_submit_state *state)
 {
 	blk_finish_plug(&state->plug);
 	io_file_put(state, NULL);
+	if (state->free_reqs)
+		kmem_cache_free_bulk(req_cachep, state->free_reqs,
+					&state->reqs[state->cur_req]);
 }
 
 /*
@@ -985,6 +1015,7 @@ static void io_submit_state_start(struct io_submit_state *state,
 				  struct io_ring_ctx *ctx, unsigned max_ios)
 {
 	blk_start_plug(&state->plug);
+	state->free_reqs = 0;
 	state->file = NULL;
 	state->ios_left = max_ios;
 }
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 11/18] block: implement bio helper to add iter bvec pages to bio
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (9 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 10/18] io_uring: batch io_kiocb allocation Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers Jens Axboe
                   ` (6 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

For an ITER_BVEC, we can just iterate the iov and add the pages
to the bio directly. This requires that the caller doesn't releases
the pages on IO completion, we add a BIO_NO_PAGE_REF flag for that.

The current two callers of bio_iov_iter_get_pages() are updated to
check if they need to release pages on completion. This makes them
work with bvecs that contain kernel mapped pages already.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 block/bio.c               | 59 ++++++++++++++++++++++++++++++++-------
 fs/block_dev.c            |  5 ++--
 fs/iomap.c                |  5 ++--
 include/linux/blk_types.h |  1 +
 4 files changed, 56 insertions(+), 14 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 4db1008309ed..330df572cfb8 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -828,6 +828,23 @@ int bio_add_page(struct bio *bio, struct page *page,
 }
 EXPORT_SYMBOL(bio_add_page);
 
+static int __bio_iov_bvec_add_pages(struct bio *bio, struct iov_iter *iter)
+{
+	const struct bio_vec *bv = iter->bvec;
+	unsigned int len;
+	size_t size;
+
+	len = min_t(size_t, bv->bv_len, iter->count);
+	size = bio_add_page(bio, bv->bv_page, len,
+				bv->bv_offset + iter->iov_offset);
+	if (size == len) {
+		iov_iter_advance(iter, size);
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 #define PAGE_PTRS_PER_BVEC     (sizeof(struct bio_vec) / sizeof(struct page *))
 
 /**
@@ -876,23 +893,43 @@ static int __bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 }
 
 /**
- * bio_iov_iter_get_pages - pin user or kernel pages and add them to a bio
+ * bio_iov_iter_get_pages - add user or kernel pages to a bio
  * @bio: bio to add pages to
- * @iter: iov iterator describing the region to be mapped
+ * @iter: iov iterator describing the region to be added
+ *
+ * This takes either an iterator pointing to user memory, or one pointing to
+ * kernel pages (BVEC iterator). If we're adding user pages, we pin them and
+ * map them into the kernel. On IO completion, the caller should put those
+ * pages. If we're adding kernel pages, we just have to add the pages to the
+ * bio directly. We don't grab an extra reference to those pages (the user
+ * should already have that), and we don't put the page on IO completion.
+ * The caller needs to check if the bio is flagged BIO_NO_PAGE_REF on IO
+ * completion. If it isn't, then pages should be released.
  *
- * Pins pages from *iter and appends them to @bio's bvec array. The
- * pages will have to be released using put_page() when done.
  * The function tries, but does not guarantee, to pin as many pages as
- * fit into the bio, or are requested in *iter, whatever is smaller.
- * If MM encounters an error pinning the requested pages, it stops.
- * Error is returned only if 0 pages could be pinned.
+ * fit into the bio, or are requested in *iter, whatever is smaller. If
+ * MM encounters an error pinning the requested pages, it stops. Error
+ * is returned only if 0 pages could be pinned.
  */
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter)
 {
+	const bool is_bvec = iov_iter_is_bvec(iter);
 	unsigned short orig_vcnt = bio->bi_vcnt;
 
+	/*
+	 * If this is a BVEC iter, then the pages are kernel pages. Don't
+	 * release them on IO completion.
+	 */
+	if (is_bvec)
+		bio_set_flag(bio, BIO_NO_PAGE_REF);
+
 	do {
-		int ret = __bio_iov_iter_get_pages(bio, iter);
+		int ret;
+
+		if (is_bvec)
+			ret = __bio_iov_bvec_add_pages(bio, iter);
+		else
+			ret = __bio_iov_iter_get_pages(bio, iter);
 
 		if (unlikely(ret))
 			return bio->bi_vcnt > orig_vcnt ? 0 : ret;
@@ -1634,7 +1671,8 @@ static void bio_dirty_fn(struct work_struct *work)
 		next = bio->bi_private;
 
 		bio_set_pages_dirty(bio);
-		bio_release_pages(bio);
+		if (!bio_flagged(bio, BIO_NO_PAGE_REF))
+			bio_release_pages(bio);
 		bio_put(bio);
 	}
 }
@@ -1650,7 +1688,8 @@ void bio_check_pages_dirty(struct bio *bio)
 			goto defer;
 	}
 
-	bio_release_pages(bio);
+	if (!bio_flagged(bio, BIO_NO_PAGE_REF))
+		bio_release_pages(bio);
 	bio_put(bio);
 	return;
 defer:
diff --git a/fs/block_dev.c b/fs/block_dev.c
index 392e2bfb636f..051ab41d1c61 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -338,8 +338,9 @@ static void blkdev_bio_end_io(struct bio *bio)
 		struct bio_vec *bvec;
 		int i;
 
-		bio_for_each_segment_all(bvec, bio, i)
-			put_page(bvec->bv_page);
+		if (!bio_flagged(bio, BIO_NO_PAGE_REF))
+			bio_for_each_segment_all(bvec, bio, i)
+				put_page(bvec->bv_page);
 		bio_put(bio);
 	}
 }
diff --git a/fs/iomap.c b/fs/iomap.c
index 2ac9eb746d44..9389cf0a1c6f 100644
--- a/fs/iomap.c
+++ b/fs/iomap.c
@@ -1591,8 +1591,9 @@ static void iomap_dio_bio_end_io(struct bio *bio)
 		struct bio_vec *bvec;
 		int i;
 
-		bio_for_each_segment_all(bvec, bio, i)
-			put_page(bvec->bv_page);
+		if (!bio_flagged(bio, BIO_NO_PAGE_REF))
+			bio_for_each_segment_all(bvec, bio, i)
+				put_page(bvec->bv_page);
 		bio_put(bio);
 	}
 }
diff --git a/include/linux/blk_types.h b/include/linux/blk_types.h
index d66bf5f32610..791fee35df88 100644
--- a/include/linux/blk_types.h
+++ b/include/linux/blk_types.h
@@ -215,6 +215,7 @@ struct bio {
 /*
  * bio flags
  */
+#define BIO_NO_PAGE_REF	0	/* don't put release vec pages */
 #define BIO_SEG_VALID	1	/* bi_phys_segments valid */
 #define BIO_CLONED	2	/* doesn't own data */
 #define BIO_BOUNCED	3	/* bio is a bounce bio */
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (10 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 11/18] block: implement bio helper to add iter bvec pages to bio Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 20:57   ` Jeff Moyer
  2019-02-07 22:38   ` Jeff Moyer
  2019-02-07 19:55 ` [PATCH 13/18] io_uring: add file set registration Jens Axboe
                   ` (5 subsequent siblings)
  17 siblings, 2 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

If we have fixed user buffers, we can map them into the kernel when we
setup the io_context. That avoids the need to do get_user_pages() for
each and every IO.

To utilize this feature, the application must call io_uring_register()
after having setup an io_uring context, passing in
IORING_REGISTER_BUFFERS as the opcode. The argument must be a pointer
to an iovec array, and the nr_args should contain how many iovecs the
application wishes to map.

If successful, these buffers are now mapped into the kernel, eligible
for IO. To use these fixed buffers, the application must use the
IORING_OP_READ_FIXED and IORING_OP_WRITE_FIXED opcodes, and then
set sqe->index to the desired buffer index. sqe->addr..sqe->addr+seq->len
must point to somewhere inside the indexed buffer.

The application may register buffers throughout the lifetime of the
io_uring context. It can call io_uring_register() with
IORING_UNREGISTER_BUFFERS as the opcode to unregister the current set of
buffers, and then register a new set. The application need not
unregister buffers explicitly before shutting down the io_uring context.

It's perfectly valid to setup a larger buffer, and then sometimes only
use parts of it for an IO. As long as the range is within the originally
mapped region, it will work just fine.

For now, buffers must not be file backed. If file backed buffers are
passed in, the registration will fail with -1/EOPNOTSUPP. This
restriction may be relaxed in the future.

RLIMIT_MEMLOCK is used to check how much memory we can pin. A somewhat
arbitrary 1G per buffer size is also imposed.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 arch/x86/entry/syscalls/syscall_32.tbl |   1 +
 arch/x86/entry/syscalls/syscall_64.tbl |   1 +
 fs/io_uring.c                          | 356 ++++++++++++++++++++++++-
 include/linux/sched/user.h             |   2 +-
 include/linux/syscalls.h               |   2 +
 include/uapi/asm-generic/unistd.h      |   4 +-
 include/uapi/linux/io_uring.h          |  13 +-
 kernel/sys_ni.c                        |   1 +
 8 files changed, 363 insertions(+), 17 deletions(-)

diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
index 481c126259e9..2eefd2a7c1ce 100644
--- a/arch/x86/entry/syscalls/syscall_32.tbl
+++ b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -400,3 +400,4 @@
 386	i386	rseq			sys_rseq			__ia32_sys_rseq
 425	i386	io_uring_setup		sys_io_uring_setup		__ia32_sys_io_uring_setup
 426	i386	io_uring_enter		sys_io_uring_enter		__ia32_sys_io_uring_enter
+427	i386	io_uring_register	sys_io_uring_register		__ia32_sys_io_uring_register
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
index 6a32a430c8e0..65c026185e61 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -345,6 +345,7 @@
 334	common	rseq			__x64_sys_rseq
 425	common	io_uring_setup		__x64_sys_io_uring_setup
 426	common	io_uring_enter		__x64_sys_io_uring_enter
+427	common	io_uring_register	__x64_sys_io_uring_register
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
diff --git a/fs/io_uring.c b/fs/io_uring.c
index 1369cb95e1b5..9d6233dc35ca 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -25,6 +25,7 @@
 #include <linux/slab.h>
 #include <linux/workqueue.h>
 #include <linux/blkdev.h>
+#include <linux/bvec.h>
 #include <linux/net.h>
 #include <net/sock.h>
 #include <net/af_unix.h>
@@ -32,6 +33,7 @@
 #include <linux/sched/mm.h>
 #include <linux/uaccess.h>
 #include <linux/nospec.h>
+#include <linux/sizes.h>
 
 #include <uapi/linux/io_uring.h>
 
@@ -61,6 +63,13 @@ struct io_cq_ring {
 	struct io_uring_cqe	cqes[];
 };
 
+struct io_mapped_ubuf {
+	u64		ubuf;
+	size_t		len;
+	struct		bio_vec *bvec;
+	unsigned int	nr_bvecs;
+};
+
 struct io_ring_ctx {
 	struct {
 		struct percpu_ref	refs;
@@ -92,6 +101,10 @@ struct io_ring_ctx {
 		struct fasync_struct	*cq_fasync;
 	} ____cacheline_aligned_in_smp;
 
+	/* if used, fixed mapped user buffers */
+	unsigned		nr_user_bufs;
+	struct io_mapped_ubuf	*user_bufs;
+
 	struct user_struct	*user;
 
 	struct completion	ctx_done;
@@ -703,6 +716,44 @@ static inline void io_rw_done(struct kiocb *kiocb, ssize_t ret)
 	}
 }
 
+static int io_import_fixed(struct io_ring_ctx *ctx, int rw,
+			   const struct io_uring_sqe *sqe,
+			   struct iov_iter *iter)
+{
+	size_t len = READ_ONCE(sqe->len);
+	struct io_mapped_ubuf *imu;
+	unsigned index, buf_index;
+	size_t offset;
+	u64 buf_addr;
+
+	/* attempt to use fixed buffers without having provided iovecs */
+	if (unlikely(!ctx->user_bufs))
+		return -EFAULT;
+
+	buf_index = READ_ONCE(sqe->buf_index);
+	if (unlikely(buf_index >= ctx->nr_user_bufs))
+		return -EFAULT;
+
+	index = array_index_nospec(buf_index, ctx->nr_user_bufs);
+	imu = &ctx->user_bufs[index];
+	buf_addr = READ_ONCE(sqe->addr);
+
+	if (buf_addr + len < buf_addr)
+		return -EFAULT;
+	if (buf_addr < imu->ubuf || buf_addr + len > imu->ubuf + imu->len)
+		return -EFAULT;
+
+	/*
+	 * May not be a start of buffer, set size appropriately
+	 * and advance us to the beginning.
+	 */
+	offset = buf_addr - imu->ubuf;
+	iov_iter_bvec(iter, rw, imu->bvec, imu->nr_bvecs, offset + len);
+	if (offset)
+		iov_iter_advance(iter, offset);
+	return 0;
+}
+
 static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
 			   const struct sqe_submit *s, struct iovec **iovec,
 			   struct iov_iter *iter)
@@ -710,6 +761,15 @@ static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
 	const struct io_uring_sqe *sqe = s->sqe;
 	void __user *buf = u64_to_user_ptr(READ_ONCE(sqe->addr));
 	size_t sqe_len = READ_ONCE(sqe->len);
+	u8 opcode;
+
+	opcode = READ_ONCE(sqe->opcode);
+	if (opcode == IORING_OP_READ_FIXED ||
+	    opcode == IORING_OP_WRITE_FIXED) {
+		ssize_t ret = io_import_fixed(ctx, rw, sqe, iter);
+		*iovec = NULL;
+		return ret;
+	}
 
 	if (!s->has_user)
 		return EFAULT;
@@ -853,7 +913,7 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 
 	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
 		return -EINVAL;
-	if (unlikely(sqe->addr || sqe->ioprio))
+	if (unlikely(sqe->addr || sqe->ioprio || sqe->buf_index))
 		return -EINVAL;
 
 	fsync_flags = READ_ONCE(sqe->fsync_flags);
@@ -891,9 +951,19 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 		ret = io_nop(req, req->user_data);
 		break;
 	case IORING_OP_READV:
+		if (unlikely(s->sqe->buf_index))
+			return -EINVAL;
 		ret = io_read(req, s, force_nonblock, state);
 		break;
 	case IORING_OP_WRITEV:
+		if (unlikely(s->sqe->buf_index))
+			return -EINVAL;
+		ret = io_write(req, s, force_nonblock, state);
+		break;
+	case IORING_OP_READ_FIXED:
+		ret = io_read(req, s, force_nonblock, state);
+		break;
+	case IORING_OP_WRITE_FIXED:
 		ret = io_write(req, s, force_nonblock, state);
 		break;
 	case IORING_OP_FSYNC:
@@ -922,28 +992,47 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	return 0;
 }
 
+static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
+{
+	u8 opcode = READ_ONCE(sqe->opcode);
+
+	return !(opcode == IORING_OP_READ_FIXED ||
+		 opcode == IORING_OP_WRITE_FIXED);
+}
+
 static void io_sq_wq_submit_work(struct work_struct *work)
 {
 	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
 	struct sqe_submit *s = &req->submit;
-	u64 user_data = READ_ONCE(s->sqe->user_data);
 	struct io_ring_ctx *ctx = req->ctx;
-	mm_segment_t old_fs = get_fs();
+	mm_segment_t old_fs;
+	bool needs_user;
+	u64 user_data;
 	int ret;
 
 	 /* Ensure we clear previously set forced non-block flag */
 	req->flags &= ~REQ_F_FORCE_NONBLOCK;
 	req->rw.ki_flags &= ~IOCB_NOWAIT;
 
-	if (!mmget_not_zero(ctx->sqo_mm)) {
-		ret = -EFAULT;
-		goto err;
-	}
-
-	use_mm(ctx->sqo_mm);
-	set_fs(USER_DS);
-	s->has_user = true;
+	user_data = READ_ONCE(s->sqe->user_data);
 	s->needs_lock = true;
+	s->has_user = false;
+
+	/*
+	 * If we're doing IO to fixed buffers, we don't need to get/set
+	 * user context
+	 */
+	needs_user = io_sqe_needs_user(s->sqe);
+	if (needs_user) {
+		if (!mmget_not_zero(ctx->sqo_mm)) {
+			ret = -EFAULT;
+			goto err;
+		}
+		use_mm(ctx->sqo_mm);
+		old_fs = get_fs();
+		set_fs(USER_DS);
+		s->has_user = true;
+	}
 
 	do {
 		ret = __io_submit_sqe(ctx, req, s, false, NULL);
@@ -957,9 +1046,11 @@ static void io_sq_wq_submit_work(struct work_struct *work)
 		cond_resched();
 	} while (1);
 
-	set_fs(old_fs);
-	unuse_mm(ctx->sqo_mm);
-	mmput(ctx->sqo_mm);
+	if (needs_user) {
+		set_fs(old_fs);
+		unuse_mm(ctx->sqo_mm);
+		mmput(ctx->sqo_mm);
+	}
 err:
 	if (ret) {
 		io_cqring_add_event(ctx, user_data, ret, 0);
@@ -1241,6 +1332,188 @@ static unsigned long ring_pages(unsigned sq_entries, unsigned cq_entries)
 	return (bytes + PAGE_SIZE - 1) / PAGE_SIZE;
 }
 
+static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
+{
+	int i, j;
+
+	if (!ctx->user_bufs)
+		return -ENXIO;
+
+	for (i = 0; i < ctx->sq_entries; i++) {
+		struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
+
+		for (j = 0; j < imu->nr_bvecs; j++)
+			put_page(imu->bvec[j].bv_page);
+
+		io_unaccount_mem(ctx->user, imu->nr_bvecs);
+		kfree(imu->bvec);
+		imu->nr_bvecs = 0;
+	}
+
+	kfree(ctx->user_bufs);
+	ctx->user_bufs = NULL;
+	free_uid(ctx->user);
+	ctx->user = NULL;
+	return 0;
+}
+
+static int io_copy_iov(struct io_ring_ctx *ctx, struct iovec *dst,
+		       void __user *arg, unsigned index)
+{
+	struct iovec __user *src;
+
+#ifdef CONFIG_COMPAT
+	if (ctx->compat) {
+		struct compat_iovec __user *ciovs;
+		struct compat_iovec ciov;
+
+		ciovs = (struct compat_iovec __user *) arg;
+		if (copy_from_user(&ciov, &ciovs[index], sizeof(ciov)))
+			return -EFAULT;
+
+		dst->iov_base = (void __user *) (unsigned long) ciov.iov_base;
+		dst->iov_len = ciov.iov_len;
+		return 0;
+	}
+#endif
+	src = (struct iovec __user *) arg;
+	if (copy_from_user(dst, &src[index], sizeof(*dst)))
+		return -EFAULT;
+	return 0;
+}
+
+static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
+				  unsigned nr_args)
+{
+	struct vm_area_struct **vmas = NULL;
+	struct page **pages = NULL;
+	int i, j, got_pages = 0;
+	int ret = -EINVAL;
+
+	if (ctx->user_bufs)
+		return -EBUSY;
+	if (!nr_args || nr_args > UIO_MAXIOV)
+		return -EINVAL;
+
+	ctx->user_bufs = kcalloc(nr_args, sizeof(struct io_mapped_ubuf),
+					GFP_KERNEL);
+	if (!ctx->user_bufs)
+		return -ENOMEM;
+
+	for (i = 0; i < nr_args; i++) {
+		struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
+		unsigned long off, start, end, ubuf;
+		int pret, nr_pages;
+		struct iovec iov;
+		size_t size;
+
+		ret = io_copy_iov(ctx, &iov, arg, i);
+		if (ret)
+			break;
+
+		/*
+		 * Don't impose further limits on the size and buffer
+		 * constraints here, we'll -EINVAL later when IO is
+		 * submitted if they are wrong.
+		 */
+		ret = -EFAULT;
+		if (!iov.iov_base || !iov.iov_len)
+			goto err;
+
+		/* arbitrary limit, but we need something */
+		if (iov.iov_len > SZ_1G)
+			goto err;
+
+		ubuf = (unsigned long) iov.iov_base;
+		end = (ubuf + iov.iov_len + PAGE_SIZE - 1) >> PAGE_SHIFT;
+		start = ubuf >> PAGE_SHIFT;
+		nr_pages = end - start;
+
+		ret = io_account_mem(ctx->user, nr_pages);
+		if (ret)
+			goto err;
+
+		if (!pages || nr_pages > got_pages) {
+			kfree(vmas);
+			kfree(pages);
+			pages = kmalloc_array(nr_pages, sizeof(struct page *),
+						GFP_KERNEL);
+			vmas = kmalloc_array(nr_pages,
+					sizeof(struct vma_area_struct *),
+					GFP_KERNEL);
+			if (!pages || !vmas) {
+				ret = -ENOMEM;
+				io_unaccount_mem(ctx->user, nr_pages);
+				goto err;
+			}
+			got_pages = nr_pages;
+		}
+
+		imu->bvec = kmalloc_array(nr_pages, sizeof(struct bio_vec),
+						GFP_KERNEL);
+		if (!imu->bvec) {
+			io_unaccount_mem(ctx->user, nr_pages);
+			goto err;
+		}
+
+		down_write(&current->mm->mmap_sem);
+		pret = get_user_pages_longterm(ubuf, nr_pages, FOLL_WRITE,
+						pages, vmas);
+		if (pret == nr_pages) {
+			/* don't support file backed memory */
+			for (j = 0; j < nr_pages; j++) {
+				struct vm_area_struct *vma = vmas[j];
+
+				if (vma->vm_file) {
+					ret = -EOPNOTSUPP;
+					break;
+				}
+			}
+		} else {
+			ret = pret < 0 ? pret : -EFAULT;
+		}
+		up_write(&current->mm->mmap_sem);
+		if (ret) {
+			/*
+			 * if we did partial map, or found file backed vmas,
+			 * release any pages we did get
+			 */
+			if (pret > 0) {
+				for (j = 0; j < pret; j++)
+					put_page(pages[j]);
+			}
+			io_unaccount_mem(ctx->user, nr_pages);
+			goto err;
+		}
+
+		off = ubuf & ~PAGE_MASK;
+		size = iov.iov_len;
+		for (j = 0; j < nr_pages; j++) {
+			size_t vec_len;
+
+			vec_len = min_t(size_t, size, PAGE_SIZE - off);
+			imu->bvec[j].bv_page = pages[j];
+			imu->bvec[j].bv_len = vec_len;
+			imu->bvec[j].bv_offset = off;
+			off = 0;
+			size -= vec_len;
+		}
+		/* store original address for later verification */
+		imu->ubuf = ubuf;
+		imu->len = iov.iov_len;
+		imu->nr_bvecs = nr_pages;
+	}
+	kfree(pages);
+	kfree(vmas);
+	ctx->nr_user_bufs = nr_args;
+	return 0;
+err:
+	kfree(pages);
+	kfree(vmas);
+	io_sqe_buffer_unregister(ctx);
+	return ret;
+}
+
 static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 {
 	if (ctx->sqo_wq)
@@ -1253,6 +1526,7 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 #endif
 
 	io_iopoll_reap_events(ctx);
+	io_sqe_buffer_unregister(ctx);
 
 	io_mem_free(ctx->sq_ring);
 	io_mem_free(ctx->sq_sqes);
@@ -1593,6 +1867,60 @@ SYSCALL_DEFINE2(io_uring_setup, u32, entries,
 	return io_uring_setup(entries, params);
 }
 
+static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
+			       void __user *arg, unsigned nr_args)
+{
+	int ret;
+
+	percpu_ref_kill(&ctx->refs);
+	wait_for_completion(&ctx->ctx_done);
+
+	switch (opcode) {
+	case IORING_REGISTER_BUFFERS:
+		ret = io_sqe_buffer_register(ctx, arg, nr_args);
+		break;
+	case IORING_UNREGISTER_BUFFERS:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_sqe_buffer_unregister(ctx);
+		break;
+	default:
+		ret = -EINVAL;
+		break;
+	}
+
+	/* bring the ctx back to life */
+	reinit_completion(&ctx->ctx_done);
+	percpu_ref_reinit(&ctx->refs);
+	return ret;
+}
+
+SYSCALL_DEFINE4(io_uring_register, unsigned int, fd, unsigned int, opcode,
+		void __user *, arg, unsigned int, nr_args)
+{
+	struct io_ring_ctx *ctx;
+	long ret = -EBADF;
+	struct fd f;
+
+	f = fdget(fd);
+	if (!f.file)
+		return -EBADF;
+
+	ret = -EOPNOTSUPP;
+	if (f.file->f_op != &io_uring_fops)
+		goto out_fput;
+
+	ctx = f.file->private_data;
+
+	mutex_lock(&ctx->uring_lock);
+	ret = __io_uring_register(ctx, opcode, arg, nr_args);
+	mutex_unlock(&ctx->uring_lock);
+out_fput:
+	fdput(f);
+	return ret;
+}
+
 static int __init io_uring_init(void)
 {
 	req_cachep = KMEM_CACHE(io_kiocb, SLAB_HWCACHE_ALIGN | SLAB_PANIC);
diff --git a/include/linux/sched/user.h b/include/linux/sched/user.h
index 39ad98c09c58..c7b5f86b91a1 100644
--- a/include/linux/sched/user.h
+++ b/include/linux/sched/user.h
@@ -40,7 +40,7 @@ struct user_struct {
 	kuid_t uid;
 
 #if defined(CONFIG_PERF_EVENTS) || defined(CONFIG_BPF_SYSCALL) || \
-    defined(CONFIG_NET)
+    defined(CONFIG_NET) || defined(CONFIG_IO_URING)
 	atomic_long_t locked_vm;
 #endif
 
diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
index 3072dbaa7869..3681c05ac538 100644
--- a/include/linux/syscalls.h
+++ b/include/linux/syscalls.h
@@ -315,6 +315,8 @@ asmlinkage long sys_io_uring_setup(u32 entries,
 asmlinkage long sys_io_uring_enter(unsigned int fd, u32 to_submit,
 				u32 min_complete, u32 flags,
 				const sigset_t __user *sig, size_t sigsz);
+asmlinkage long sys_io_uring_register(unsigned int fd, unsigned int op,
+				void __user *arg, unsigned int nr_args);
 
 /* fs/xattr.c */
 asmlinkage long sys_setxattr(const char __user *path, const char __user *name,
diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
index 87871e7b7ea7..d346229a1eb0 100644
--- a/include/uapi/asm-generic/unistd.h
+++ b/include/uapi/asm-generic/unistd.h
@@ -744,9 +744,11 @@ __SYSCALL(__NR_kexec_file_load,     sys_kexec_file_load)
 __SYSCALL(__NR_io_uring_setup, sys_io_uring_setup)
 #define __NR_io_uring_enter 426
 __SYSCALL(__NR_io_uring_enter, sys_io_uring_enter)
+#define __NR_io_uring_register 427
+__SYSCALL(__NR_io_uring_register, sys_io_uring_register)
 
 #undef __NR_syscalls
-#define __NR_syscalls 427
+#define __NR_syscalls 428
 
 /*
  * 32 bit systems traditionally used different
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 5c457ea396e6..cf28f7a11f12 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -27,7 +27,10 @@ struct io_uring_sqe {
 		__u32		fsync_flags;
 	};
 	__u64	user_data;	/* data to be passed back at completion time */
-	__u64	__pad2[3];
+	union {
+		__u16	buf_index;	/* index into fixed buffers, if used */
+		__u64	__pad2[3];
+	};
 };
 
 /*
@@ -39,6 +42,8 @@ struct io_uring_sqe {
 #define IORING_OP_READV		1
 #define IORING_OP_WRITEV	2
 #define IORING_OP_FSYNC		3
+#define IORING_OP_READ_FIXED	4
+#define IORING_OP_WRITE_FIXED	5
 
 /*
  * sqe->fsync_flags
@@ -103,4 +108,10 @@ struct io_uring_params {
 	struct io_cqring_offsets cq_off;
 };
 
+/*
+ * io_uring_register(2) opcodes and arguments
+ */
+#define IORING_REGISTER_BUFFERS		0
+#define IORING_UNREGISTER_BUFFERS	1
+
 #endif
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index ee5e523564bb..1bb6604dc19f 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -48,6 +48,7 @@ COND_SYSCALL_COMPAT(io_getevents);
 COND_SYSCALL_COMPAT(io_pgetevents);
 COND_SYSCALL(io_uring_setup);
 COND_SYSCALL(io_uring_enter);
+COND_SYSCALL(io_uring_register);
 
 /* fs/xattr.c */
 
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 13/18] io_uring: add file set registration
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (11 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-08 12:17   ` Alan Jenkins
  2019-02-07 19:55 ` [PATCH 14/18] io_uring: add submission polling Jens Axboe
                   ` (4 subsequent siblings)
  17 siblings, 1 reply; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

We normally have to fget/fput for each IO we do on a file. Even with
the batching we do, the cost of the atomic inc/dec of the file usage
count adds up.

This adds IORING_REGISTER_FILES, and IORING_UNREGISTER_FILES opcodes
for the io_uring_register(2) system call. The arguments passed in must
be an array of __s32 holding file descriptors, and nr_args should hold
the number of file descriptors the application wishes to pin for the
duration of the io_uring context (or until IORING_UNREGISTER_FILES is
called).

When used, the application must set IOSQE_FIXED_FILE in the sqe->flags
member. Then, instead of setting sqe->fd to the real fd, it sets sqe->fd
to the index in the array passed in to IORING_REGISTER_FILES.

Files are automatically unregistered when the io_uring context is
torn down. An application need only unregister if it wishes to
register a new set of fds.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c                 | 207 +++++++++++++++++++++++++++++-----
 include/net/af_unix.h         |   1 +
 include/uapi/linux/io_uring.h |   9 +-
 net/unix/af_unix.c            |   2 +-
 4 files changed, 188 insertions(+), 31 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 9d6233dc35ca..f2550efec60d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -29,6 +29,7 @@
 #include <linux/net.h>
 #include <net/sock.h>
 #include <net/af_unix.h>
+#include <net/scm.h>
 #include <linux/anon_inodes.h>
 #include <linux/sched/mm.h>
 #include <linux/uaccess.h>
@@ -101,6 +102,13 @@ struct io_ring_ctx {
 		struct fasync_struct	*cq_fasync;
 	} ____cacheline_aligned_in_smp;
 
+	/*
+	 * If used, fixed file set. Writers must ensure that ->refs is dead,
+	 * readers must ensure that ->refs is alive as long as the file* is
+	 * used. Only updated through io_uring_register(2).
+	 */
+	struct scm_fp_list	*user_files;
+
 	/* if used, fixed mapped user buffers */
 	unsigned		nr_user_bufs;
 	struct io_mapped_ubuf	*user_bufs;
@@ -148,6 +156,7 @@ struct io_kiocb {
 	unsigned int		flags;
 #define REQ_F_FORCE_NONBLOCK	1	/* inline submission attempt */
 #define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
+#define REQ_F_FIXED_FILE	4	/* ctx owns file */
 	u64			user_data;
 	u64			error;
 
@@ -374,15 +383,17 @@ static void io_iopoll_complete(struct io_ring_ctx *ctx, unsigned int *nr_events,
 		 * Batched puts of the same file, to avoid dirtying the
 		 * file usage count multiple times, if avoidable.
 		 */
-		if (!file) {
-			file = req->rw.ki_filp;
-			file_count = 1;
-		} else if (file == req->rw.ki_filp) {
-			file_count++;
-		} else {
-			fput_many(file, file_count);
-			file = req->rw.ki_filp;
-			file_count = 1;
+		if (!(req->flags & REQ_F_FIXED_FILE)) {
+			if (!file) {
+				file = req->rw.ki_filp;
+				file_count = 1;
+			} else if (file == req->rw.ki_filp) {
+				file_count++;
+			} else {
+				fput_many(file, file_count);
+				file = req->rw.ki_filp;
+				file_count = 1;
+			}
 		}
 
 		if (to_free == ARRAY_SIZE(reqs))
@@ -514,13 +525,19 @@ static void kiocb_end_write(struct kiocb *kiocb)
 	}
 }
 
+static void io_fput(struct io_kiocb *req)
+{
+	if (!(req->flags & REQ_F_FIXED_FILE))
+		fput(req->rw.ki_filp);
+}
+
 static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
 {
 	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
 
 	kiocb_end_write(kiocb);
 
-	fput(kiocb->ki_filp);
+	io_fput(req);
 	io_cqring_add_event(req->ctx, req->user_data, res, 0);
 	io_free_req(req);
 }
@@ -636,19 +653,29 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 {
 	struct io_ring_ctx *ctx = req->ctx;
 	struct kiocb *kiocb = &req->rw;
-	unsigned ioprio;
+	unsigned ioprio, flags;
 	int fd, ret;
 
 	/* For -EAGAIN retry, everything is already prepped */
 	if (kiocb->ki_filp)
 		return 0;
 
+	flags = READ_ONCE(sqe->flags);
 	fd = READ_ONCE(sqe->fd);
-	kiocb->ki_filp = io_file_get(state, fd);
-	if (unlikely(!kiocb->ki_filp))
-		return -EBADF;
-	if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
-		force_nonblock = false;
+
+	if (flags & IOSQE_FIXED_FILE) {
+		if (unlikely(!ctx->user_files ||
+		    (unsigned) fd >= ctx->user_files->count))
+			return -EBADF;
+		kiocb->ki_filp = ctx->user_files->fp[fd];
+		req->flags |= REQ_F_FIXED_FILE;
+	} else {
+		kiocb->ki_filp = io_file_get(state, fd);
+		if (unlikely(!kiocb->ki_filp))
+			return -EBADF;
+		if (force_nonblock && !io_file_supports_async(kiocb->ki_filp))
+			force_nonblock = false;
+	}
 	kiocb->ki_pos = READ_ONCE(sqe->off);
 	kiocb->ki_flags = iocb_flags(kiocb->ki_filp);
 	kiocb->ki_hint = ki_hint_validate(file_write_hint(kiocb->ki_filp));
@@ -688,10 +715,14 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	}
 	return 0;
 out_fput:
-	/* in case of error, we didn't use this file reference. drop it. */
-	if (state)
-		state->used_refs--;
-	io_file_put(state, kiocb->ki_filp);
+	if (!(flags & IOSQE_FIXED_FILE)) {
+		/*
+		 * in case of error, we didn't use this file reference. drop it.
+		 */
+		if (state)
+			state->used_refs--;
+		io_file_put(state, kiocb->ki_filp);
+	}
 	return ret;
 }
 
@@ -823,7 +854,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
 out_fput:
 	/* Hold on to the file for -EAGAIN */
 	if (unlikely(ret && ret != -EAGAIN))
-		fput(file);
+		io_fput(req);
 	return ret;
 }
 
@@ -877,7 +908,7 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
 	kfree(iovec);
 out_fput:
 	if (unlikely(ret))
-		fput(file);
+		io_fput(req);
 	return ret;
 }
 
@@ -903,7 +934,7 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	loff_t sqe_off = READ_ONCE(sqe->off);
 	loff_t sqe_len = READ_ONCE(sqe->len);
 	loff_t end = sqe_off + sqe_len;
-	unsigned fsync_flags;
+	unsigned fsync_flags, flags;
 	struct file *file;
 	int ret, fd;
 
@@ -921,14 +952,23 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		return -EINVAL;
 
 	fd = READ_ONCE(sqe->fd);
-	file = fget(fd);
+	flags = READ_ONCE(sqe->flags);
+
+	if (flags & IOSQE_FIXED_FILE) {
+		if (unlikely(!ctx->user_files || fd >= ctx->user_files->count))
+			return -EBADF;
+		file = ctx->user_files->fp[fd];
+	} else {
+		file = fget(fd);
+	}
 	if (unlikely(!file))
 		return -EBADF;
 
 	ret = vfs_fsync_range(file, sqe_off, end > 0 ? end : LLONG_MAX,
 				fsync_flags & IORING_FSYNC_DATASYNC);
 
-	fput(file);
+	if (!(flags & IOSQE_FIXED_FILE))
+		fput(file);
 	io_cqring_add_event(ctx, sqe->user_data, ret, 0);
 	io_free_req(req);
 	return 0;
@@ -1065,7 +1105,7 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s,
 	ssize_t ret;
 
 	/* enforce forwards compatibility on users */
-	if (unlikely(s->sqe->flags))
+	if (unlikely(s->sqe->flags & ~IOSQE_FIXED_FILE))
 		return -EINVAL;
 
 	req = io_get_req(ctx, state);
@@ -1253,6 +1293,104 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 	return ring->r.head == ring->r.tail ? ret : 0;
 }
 
+static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
+{
+#if defined(CONFIG_NET)
+	if (ctx->ring_sock) {
+		struct sock *sock = ctx->ring_sock->sk;
+		struct sk_buff *skb;
+
+		while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
+			kfree_skb(skb);
+	}
+#else
+	int i;
+
+	for (i = 0; i < ctx->user_files->count; i++)
+		fput(ctx->user_files->fp[i]);
+
+	kfree(ctx->user_files);
+#endif
+}
+
+static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
+{
+	if (!ctx->user_files)
+		return -ENXIO;
+
+	__io_sqe_files_unregister(ctx);
+	ctx->user_files = NULL;
+	return 0;
+}
+
+static int io_sqe_files_scm(struct io_ring_ctx *ctx)
+{
+#if defined(CONFIG_NET)
+	struct scm_fp_list *fpl = ctx->user_files;
+	struct sk_buff *skb;
+	int i;
+
+	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
+	if (!skb)
+		return -ENOMEM;
+
+	skb->sk = ctx->ring_sock->sk;
+	skb->destructor = unix_destruct_scm;
+
+	fpl->user = get_uid(ctx->user);
+	for (i = 0; i < fpl->count; i++) {
+		get_file(fpl->fp[i]);
+		unix_inflight(fpl->user, fpl->fp[i]);
+		fput(fpl->fp[i]);
+	}
+
+	UNIXCB(skb).fp = fpl;
+	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
+#endif
+	return 0;
+}
+
+static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
+				 unsigned nr_args)
+{
+	__s32 __user *fds = (__s32 __user *) arg;
+	struct scm_fp_list *fpl;
+	int fd, ret = 0;
+	unsigned i;
+
+	if (ctx->user_files)
+		return -EBUSY;
+	if (!nr_args || nr_args > SCM_MAX_FD)
+		return -EINVAL;
+
+	fpl = kzalloc(sizeof(*ctx->user_files), GFP_KERNEL);
+	if (!fpl)
+		return -ENOMEM;
+	fpl->max = nr_args;
+
+	for (i = 0; i < nr_args; i++) {
+		ret = -EFAULT;
+		if (copy_from_user(&fd, &fds[i], sizeof(fd)))
+			break;
+
+		fpl->fp[i] = fget(fd);
+
+		ret = -EBADF;
+		if (!fpl->fp[i])
+			break;
+		fpl->count++;
+		ret = 0;
+	}
+
+	ctx->user_files = fpl;
+	if (!ret)
+		ret = io_sqe_files_scm(ctx);
+	if (ret)
+		io_sqe_files_unregister(ctx);
+
+	return ret;
+}
+
 static int io_sq_offload_start(struct io_ring_ctx *ctx)
 {
 	int ret;
@@ -1520,14 +1658,16 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 		destroy_workqueue(ctx->sqo_wq);
 	if (ctx->sqo_mm)
 		mmdrop(ctx->sqo_mm);
+
+	io_iopoll_reap_events(ctx);
+	io_sqe_buffer_unregister(ctx);
+	io_sqe_files_unregister(ctx);
+
 #if defined(CONFIG_NET)
 	if (ctx->ring_sock)
 		sock_release(ctx->ring_sock);
 #endif
 
-	io_iopoll_reap_events(ctx);
-	io_sqe_buffer_unregister(ctx);
-
 	io_mem_free(ctx->sq_ring);
 	io_mem_free(ctx->sq_sqes);
 	io_mem_free(ctx->cq_ring);
@@ -1885,6 +2025,15 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
 			break;
 		ret = io_sqe_buffer_unregister(ctx);
 		break;
+	case IORING_REGISTER_FILES:
+		ret = io_sqe_files_register(ctx, arg, nr_args);
+		break;
+	case IORING_UNREGISTER_FILES:
+		ret = -EINVAL;
+		if (arg || nr_args)
+			break;
+		ret = io_sqe_files_unregister(ctx);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
diff --git a/include/net/af_unix.h b/include/net/af_unix.h
index ddbba838d048..3426d6dacc45 100644
--- a/include/net/af_unix.h
+++ b/include/net/af_unix.h
@@ -10,6 +10,7 @@
 
 void unix_inflight(struct user_struct *user, struct file *fp);
 void unix_notinflight(struct user_struct *user, struct file *fp);
+void unix_destruct_scm(struct sk_buff *skb);
 void unix_gc(void);
 void wait_for_unix_gc(void);
 struct sock *unix_get_socket(struct file *filp);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index cf28f7a11f12..6257478d55e9 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -16,7 +16,7 @@
  */
 struct io_uring_sqe {
 	__u8	opcode;		/* type of operation for this sqe */
-	__u8	flags;		/* as of now unused */
+	__u8	flags;		/* IOSQE_ flags */
 	__u16	ioprio;		/* ioprio for the request */
 	__s32	fd;		/* file descriptor to do IO on */
 	__u64	off;		/* offset into file */
@@ -33,6 +33,11 @@ struct io_uring_sqe {
 	};
 };
 
+/*
+ * sqe->flags
+ */
+#define IOSQE_FIXED_FILE	(1U << 0)	/* use fixed fileset */
+
 /*
  * io_uring_setup() flags
  */
@@ -113,5 +118,7 @@ struct io_uring_params {
  */
 #define IORING_REGISTER_BUFFERS		0
 #define IORING_UNREGISTER_BUFFERS	1
+#define IORING_REGISTER_FILES		2
+#define IORING_UNREGISTER_FILES		3
 
 #endif
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 74d1eed7cbd4..9b1bbf74c4ea 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -1497,7 +1497,7 @@ static void unix_detach_fds(struct scm_cookie *scm, struct sk_buff *skb)
 		unix_notinflight(scm->fp->user, scm->fp->fp[i]);
 }
 
-static void unix_destruct_scm(struct sk_buff *skb)
+void unix_destruct_scm(struct sk_buff *skb)
 {
 	struct scm_cookie scm;
 	memset(&scm, 0, sizeof(scm));
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 14/18] io_uring: add submission polling
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (12 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 13/18] io_uring: add file set registration Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 15/18] io_uring: add io_kiocb ref count Jens Axboe
                   ` (3 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

This enables an application to do IO, without ever entering the kernel.
By using the SQ ring to fill in new sqes and watching for completions
on the CQ ring, we can submit and reap IOs without doing a single system
call. The kernel side thread will poll for new submissions, and in case
of HIPRI/polled IO, it'll also poll for completions.

By default, we allow 1 second of active spinning. This can by changed
by passing in a different grace period at io_uring_register(2) time.
If the thread exceeds this idle time without having any work to do, it
will set:

sq_ring->flags |= IORING_SQ_NEED_WAKEUP.

The application will have to call io_uring_enter() to start things back
up again. If IO is kept busy, that will never be needed. Basically an
application that has this feature enabled will guard it's
io_uring_enter(2) call with:

read_barrier();
if (*sq_ring->flags & IORING_SQ_NEED_WAKEUP)
	io_uring_enter(fd, 0, 0, IORING_ENTER_SQ_WAKEUP);

instead of calling it unconditionally.

It's mandatory to use fixed files with this feature. Failure to do so
will result in the application getting an -EBADF CQ entry when
submitting IO.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c                 | 249 +++++++++++++++++++++++++++++++++-
 include/uapi/linux/io_uring.h |  12 +-
 2 files changed, 253 insertions(+), 8 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index f2550efec60d..200631cf3955 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -24,6 +24,7 @@
 #include <linux/percpu.h>
 #include <linux/slab.h>
 #include <linux/workqueue.h>
+#include <linux/kthread.h>
 #include <linux/blkdev.h>
 #include <linux/bvec.h>
 #include <linux/net.h>
@@ -85,12 +86,16 @@ struct io_ring_ctx {
 		unsigned		cached_sq_head;
 		unsigned		sq_entries;
 		unsigned		sq_mask;
+		unsigned		sq_thread_idle;
 		struct io_uring_sqe	*sq_sqes;
 	} ____cacheline_aligned_in_smp;
 
 	/* IO offload */
 	struct workqueue_struct	*sqo_wq;
+	struct task_struct	*sqo_thread;	/* if using sq thread polling */
 	struct mm_struct	*sqo_mm;
+	wait_queue_head_t	sqo_wait;
+	unsigned		sqo_stop;
 
 	struct {
 		/* CQ ring */
@@ -144,6 +149,7 @@ struct sqe_submit {
 	unsigned short			index;
 	bool				has_user;
 	bool				needs_lock;
+	bool				needs_fixed_file;
 };
 
 struct io_kiocb {
@@ -295,6 +301,8 @@ static void io_cqring_add_event(struct io_ring_ctx *ctx, u64 ki_user_data,
 
 	if (waitqueue_active(&ctx->wait))
 		wake_up(&ctx->wait);
+	if (waitqueue_active(&ctx->sqo_wait))
+		wake_up(&ctx->sqo_wait);
 }
 
 static void io_ring_drop_ctx_refs(struct io_ring_ctx *ctx, unsigned refs)
@@ -648,9 +656,10 @@ static bool io_file_supports_async(struct file *file)
 	return false;
 }
 
-static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
+static int io_prep_rw(struct io_kiocb *req, const struct sqe_submit *s,
 		      bool force_nonblock, struct io_submit_state *state)
 {
+	const struct io_uring_sqe *sqe = s->sqe;
 	struct io_ring_ctx *ctx = req->ctx;
 	struct kiocb *kiocb = &req->rw;
 	unsigned ioprio, flags;
@@ -670,6 +679,8 @@ static int io_prep_rw(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 		kiocb->ki_filp = ctx->user_files->fp[fd];
 		req->flags |= REQ_F_FIXED_FILE;
 	} else {
+		if (s->needs_fixed_file)
+			return -EBADF;
 		kiocb->ki_filp = io_file_get(state, fd);
 		if (unlikely(!kiocb->ki_filp))
 			return -EBADF;
@@ -823,7 +834,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
 	struct file *file;
 	ssize_t ret;
 
-	ret = io_prep_rw(req, s->sqe, force_nonblock, state);
+	ret = io_prep_rw(req, s, force_nonblock, state);
 	if (ret)
 		return ret;
 	file = kiocb->ki_filp;
@@ -867,7 +878,7 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
 	struct file *file;
 	ssize_t ret;
 
-	ret = io_prep_rw(req, s->sqe, force_nonblock, state);
+	ret = io_prep_rw(req, s, force_nonblock, state);
 	if (ret)
 		return ret;
 	/* Hold on to the file for -EAGAIN */
@@ -1057,6 +1068,7 @@ static void io_sq_wq_submit_work(struct work_struct *work)
 	user_data = READ_ONCE(s->sqe->user_data);
 	s->needs_lock = true;
 	s->has_user = false;
+	s->needs_fixed_file = false;
 
 	/*
 	 * If we're doing IO to fixed buffers, we don't need to get/set
@@ -1211,6 +1223,170 @@ static bool io_get_sqring(struct io_ring_ctx *ctx, struct sqe_submit *s)
 	return false;
 }
 
+static int io_submit_sqes(struct io_ring_ctx *ctx, struct sqe_submit *sqes,
+			  unsigned int nr, bool has_user, bool mm_fault)
+{
+	struct io_submit_state state, *statep = NULL;
+	int ret, i, submitted = 0;
+
+	if (nr > IO_PLUG_THRESHOLD) {
+		io_submit_state_start(&state, ctx, nr);
+		statep = &state;
+	}
+
+	for (i = 0; i < nr; i++) {
+		if (unlikely(mm_fault)) {
+			ret = -EFAULT;
+		} else {
+			sqes[i].has_user = has_user;
+			sqes[i].needs_lock = true;
+			sqes[i].needs_fixed_file = true;
+			ret = io_submit_sqe(ctx, &sqes[i], statep);
+		}
+		if (!ret) {
+			submitted++;
+			continue;
+		}
+
+		io_cqring_add_event(ctx, sqes[i].sqe->user_data, ret, 0);
+	}
+
+	if (statep)
+		io_submit_state_end(&state);
+
+	return submitted;
+}
+
+static int io_sq_thread(void *data)
+{
+	struct sqe_submit sqes[IO_IOPOLL_BATCH];
+	struct io_ring_ctx *ctx = data;
+	struct mm_struct *cur_mm = NULL;
+	mm_segment_t old_fs;
+	DEFINE_WAIT(wait);
+	unsigned inflight;
+	unsigned long timeout;
+
+	old_fs = get_fs();
+	set_fs(USER_DS);
+
+	timeout = inflight = 0;
+	while (!kthread_should_stop() && !ctx->sqo_stop) {
+		bool all_fixed, mm_fault = false;
+		int i;
+
+		if (inflight) {
+			unsigned nr_events = 0;
+
+			if (ctx->flags & IORING_SETUP_IOPOLL) {
+				/*
+				 * We disallow the app entering submit/complete
+				 * with polling, but we still need to lock the
+				 * ring to prevent racing with polled issue
+				 * that got punted to a workqueue.
+				 */
+				mutex_lock(&ctx->uring_lock);
+				io_iopoll_check(ctx, &nr_events, 0);
+				mutex_unlock(&ctx->uring_lock);
+			} else {
+				/*
+				 * Normal IO, just pretend everything completed.
+				 * We don't have to poll completions for that.
+				 */
+				nr_events = inflight;
+			}
+
+			inflight -= nr_events;
+			if (!inflight)
+				timeout = jiffies + ctx->sq_thread_idle;
+		}
+
+		if (!io_get_sqring(ctx, &sqes[0])) {
+			/*
+			 * We're polling. If we're within the defined idle
+			 * period, then let us spin without work before going
+			 * to sleep.
+			 */
+			if (inflight || !time_after(jiffies, timeout)) {
+				cpu_relax();
+				continue;
+			}
+
+			/*
+			 * Drop cur_mm before scheduling, we can't hold it for
+			 * long periods (or over schedule()). Do this before
+			 * adding ourselves to the waitqueue, as the unuse/drop
+			 * may sleep.
+			 */
+			if (cur_mm) {
+				unuse_mm(cur_mm);
+				mmput(cur_mm);
+				cur_mm = NULL;
+			}
+
+			prepare_to_wait(&ctx->sqo_wait, &wait,
+						TASK_INTERRUPTIBLE);
+
+			/* Tell userspace we may need a wakeup call */
+			ctx->sq_ring->flags |= IORING_SQ_NEED_WAKEUP;
+			smp_wmb();
+
+			if (!io_get_sqring(ctx, &sqes[0])) {
+				if (kthread_should_stop()) {
+					finish_wait(&ctx->sqo_wait, &wait);
+					break;
+				}
+				if (signal_pending(current))
+					flush_signals(current);
+				schedule();
+				finish_wait(&ctx->sqo_wait, &wait);
+
+				ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP;
+				smp_wmb();
+				continue;
+			}
+			finish_wait(&ctx->sqo_wait, &wait);
+
+			ctx->sq_ring->flags &= ~IORING_SQ_NEED_WAKEUP;
+			smp_wmb();
+		}
+
+		i = 0;
+		all_fixed = true;
+		do {
+			if (all_fixed && io_sqe_needs_user(sqes[i].sqe))
+				all_fixed = false;
+
+			i++;
+			if (i == ARRAY_SIZE(sqes))
+				break;
+		} while (io_get_sqring(ctx, &sqes[i]));
+
+		io_commit_sqring(ctx);
+
+		/* Unless all new commands are FIXED regions, grab mm */
+		if (!all_fixed && !cur_mm) {
+			mm_fault = !mmget_not_zero(ctx->sqo_mm);
+			if (!mm_fault) {
+				use_mm(ctx->sqo_mm);
+				cur_mm = ctx->sqo_mm;
+			}
+		}
+
+		inflight += io_submit_sqes(ctx, sqes, i, cur_mm != NULL,
+						mm_fault);
+	}
+
+	io_iopoll_reap_events(ctx);
+
+	set_fs(old_fs);
+	if (cur_mm) {
+		unuse_mm(cur_mm);
+		mmput(cur_mm);
+	}
+	return 0;
+}
+
 static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 {
 	struct io_submit_state state, *statep = NULL;
@@ -1229,6 +1405,7 @@ static int io_ring_submit(struct io_ring_ctx *ctx, unsigned int to_submit)
 
 		s.has_user = true;
 		s.needs_lock = false;
+		s.needs_fixed_file = false;
 
 		ret = io_submit_sqe(ctx, &s, statep);
 		if (ret) {
@@ -1391,13 +1568,47 @@ static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
 	return ret;
 }
 
-static int io_sq_offload_start(struct io_ring_ctx *ctx)
+static int io_sq_offload_start(struct io_ring_ctx *ctx,
+			       struct io_uring_params *p)
 {
 	int ret;
 
+	init_waitqueue_head(&ctx->sqo_wait);
 	mmgrab(current->mm);
 	ctx->sqo_mm = current->mm;
 
+	ctx->sq_thread_idle = msecs_to_jiffies(p->sq_thread_idle);
+	if (!ctx->sq_thread_idle)
+		ctx->sq_thread_idle = HZ;
+
+	ret = -EINVAL;
+	if (!cpu_possible(p->sq_thread_cpu))
+		goto err;
+
+	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		if (p->flags & IORING_SETUP_SQ_AFF) {
+			int cpu;
+
+			cpu = array_index_nospec(p->sq_thread_cpu, NR_CPUS);
+			ctx->sqo_thread = kthread_create_on_cpu(io_sq_thread,
+							ctx, cpu,
+							"io_uring-sq");
+		} else {
+			ctx->sqo_thread = kthread_create(io_sq_thread, ctx,
+							"io_uring-sq");
+		}
+		if (IS_ERR(ctx->sqo_thread)) {
+			ret = PTR_ERR(ctx->sqo_thread);
+			ctx->sqo_thread = NULL;
+			goto err;
+		}
+		wake_up_process(ctx->sqo_thread);
+	} else if (p->flags & IORING_SETUP_SQ_AFF) {
+		/* Can't have SQ_AFF without SQPOLL */
+		ret = -EINVAL;
+		goto err;
+	}
+
 	/* Do QD, or 2 * CPUS, whatever is smallest */
 	ctx->sqo_wq = alloc_workqueue("io_ring-wq", WQ_UNBOUND | WQ_FREEZABLE,
 			min(ctx->sq_entries - 1, 2 * num_online_cpus()));
@@ -1408,6 +1619,12 @@ static int io_sq_offload_start(struct io_ring_ctx *ctx)
 
 	return 0;
 err:
+	if (ctx->sqo_thread) {
+		ctx->sqo_stop = 1;
+		mb();
+		kthread_stop(ctx->sqo_thread);
+		ctx->sqo_thread = NULL;
+	}
 	mmdrop(ctx->sqo_mm);
 	ctx->sqo_mm = NULL;
 	return ret;
@@ -1654,6 +1871,11 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
 
 static void io_ring_ctx_free(struct io_ring_ctx *ctx)
 {
+	if (ctx->sqo_thread) {
+		ctx->sqo_stop = 1;
+		mb();
+		kthread_stop(ctx->sqo_thread);
+	}
 	if (ctx->sqo_wq)
 		destroy_workqueue(ctx->sqo_wq);
 	if (ctx->sqo_mm)
@@ -1761,7 +1983,7 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 	int submitted = 0;
 	struct fd f;
 
-	if (flags & ~IORING_ENTER_GETEVENTS)
+	if (flags & ~(IORING_ENTER_GETEVENTS | IORING_ENTER_SQ_WAKEUP))
 		return -EINVAL;
 
 	f = fdget(fd);
@@ -1777,6 +1999,18 @@ SYSCALL_DEFINE6(io_uring_enter, unsigned int, fd, u32, to_submit,
 	if (!percpu_ref_tryget(&ctx->refs))
 		goto out_fput;
 
+	/*
+	 * For SQ polling, the thread will do all submissions and completions.
+	 * Just return the requested submit count, and wake the thread if
+	 * we were asked to.
+	 */
+	if (ctx->flags & IORING_SETUP_SQPOLL) {
+		if (flags & IORING_ENTER_SQ_WAKEUP)
+			wake_up(&ctx->sqo_wait);
+		submitted = to_submit;
+		goto out_ctx;
+	}
+
 	if (to_submit) {
 		to_submit = min(to_submit, ctx->sq_entries);
 
@@ -1940,7 +2174,7 @@ static int io_uring_create(unsigned entries, struct io_uring_params *p)
 	if (ret)
 		goto err;
 
-	ret = io_sq_offload_start(ctx);
+	ret = io_sq_offload_start(ctx, p);
 	if (ret)
 		goto err;
 
@@ -1988,7 +2222,8 @@ static long io_uring_setup(u32 entries, struct io_uring_params __user *params)
 			return -EINVAL;
 	}
 
-	if (p.flags & ~IORING_SETUP_IOPOLL)
+	if (p.flags & ~(IORING_SETUP_IOPOLL | IORING_SETUP_SQPOLL |
+			IORING_SETUP_SQ_AFF))
 		return -EINVAL;
 
 	ret = io_uring_create(entries, &p);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 6257478d55e9..0ec74bab8dbe 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -42,6 +42,8 @@ struct io_uring_sqe {
  * io_uring_setup() flags
  */
 #define IORING_SETUP_IOPOLL	(1U << 0)	/* io_context is polled */
+#define IORING_SETUP_SQPOLL	(1U << 1)	/* SQ poll thread */
+#define IORING_SETUP_SQ_AFF	(1U << 2)	/* sq_thread_cpu is valid */
 
 #define IORING_OP_NOP		0
 #define IORING_OP_READV		1
@@ -86,6 +88,11 @@ struct io_sqring_offsets {
 	__u64 resv2;
 };
 
+/*
+ * sq_ring->flags
+ */
+#define IORING_SQ_NEED_WAKEUP	(1U << 0) /* needs io_uring_enter wakeup */
+
 struct io_cqring_offsets {
 	__u32 head;
 	__u32 tail;
@@ -100,6 +107,7 @@ struct io_cqring_offsets {
  * io_uring_enter(2) flags
  */
 #define IORING_ENTER_GETEVENTS	(1U << 0)
+#define IORING_ENTER_SQ_WAKEUP	(1U << 1)
 
 /*
  * Passed in for io_uring_setup(2). Copied back with updated info on success
@@ -108,7 +116,9 @@ struct io_uring_params {
 	__u32 sq_entries;
 	__u32 cq_entries;
 	__u32 flags;
-	__u32 resv[7];
+	__u32 sq_thread_cpu;
+	__u32 sq_thread_idle;
+	__u32 resv[5];
 	struct io_sqring_offsets sq_off;
 	struct io_cqring_offsets cq_off;
 };
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 15/18] io_uring: add io_kiocb ref count
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (13 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 14/18] io_uring: add submission polling Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 16/18] io_uring: add support for IORING_OP_POLL Jens Axboe
                   ` (2 subsequent siblings)
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

We'll use this for the POLL implementation. Regular requests will
NOT be using references, so initialize it to 0. Any real use of
the io_kiocb ref will initialize it to at least 2.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index 200631cf3955..b54c70f8f8af 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -160,6 +160,7 @@ struct io_kiocb {
 	struct io_ring_ctx	*ctx;
 	struct list_head	list;
 	unsigned int		flags;
+	refcount_t		refs;
 #define REQ_F_FORCE_NONBLOCK	1	/* inline submission attempt */
 #define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
 #define REQ_F_FIXED_FILE	4	/* ctx owns file */
@@ -345,6 +346,7 @@ static struct io_kiocb *io_get_req(struct io_ring_ctx *ctx,
 
 	req->ctx = ctx;
 	req->flags = 0;
+	refcount_set(&req->refs, 0);
 	return req;
 out:
 	io_ring_drop_ctx_refs(ctx, 1);
@@ -362,8 +364,10 @@ static void io_free_req_many(struct io_ring_ctx *ctx, void **reqs, int *nr)
 
 static void io_free_req(struct io_kiocb *req)
 {
-	io_ring_drop_ctx_refs(req->ctx, 1);
-	kmem_cache_free(req_cachep, req);
+	if (!refcount_read(&req->refs) || refcount_dec_and_test(&req->refs)) {
+		io_ring_drop_ctx_refs(req->ctx, 1);
+		kmem_cache_free(req_cachep, req);
+	}
 }
 
 /*
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 16/18] io_uring: add support for IORING_OP_POLL
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (14 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 15/18] io_uring: add io_kiocb ref count Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 22:12   ` Jeff Moyer
  2019-02-07 19:55 ` [PATCH 17/18] io_uring: allow workqueue item to handle multiple buffered requests Jens Axboe
  2019-02-07 19:55 ` [PATCH 18/18] io_uring: add io_uring_event cache hit information Jens Axboe
  17 siblings, 1 reply; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

This is basically a direct port of bfe4037e722e, which implements a
one-shot poll command through aio. Description below is based on that
commit as well. However, instead of adding a POLL command and relying
on io_cancel(2) to remove it, we mimic the epoll(2) interface of
having a command to add a poll notification, IORING_OP_POLL_ADD,
and one to remove it again, IORING_OP_POLL_REMOVE.

To poll for a file descriptor the application should submit an sqe of
type IORING_OP_POLL. It will poll the fd for the events specified in the
poll_events field.

Unlike poll or epoll without EPOLLONESHOT this interface always works in
one shot mode, that is once the sqe is completed, it will have to be
resubmitted.

Based-on-code-from: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c                 | 256 +++++++++++++++++++++++++++++++++-
 include/uapi/linux/io_uring.h |   3 +
 2 files changed, 258 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index b54c70f8f8af..cd456fd65af7 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -137,6 +137,7 @@ struct io_ring_ctx {
 		 * manipulate the list, hence no extra locking is needed there.
 		 */
 		struct list_head	poll_list;
+		struct list_head	cancel_list;
 	} ____cacheline_aligned_in_smp;
 
 #if defined(CONFIG_NET)
@@ -152,8 +153,20 @@ struct sqe_submit {
 	bool				needs_fixed_file;
 };
 
+struct io_poll_iocb {
+	struct file *file;
+	struct wait_queue_head *head;
+	__poll_t events;
+	bool woken;
+	bool canceled;
+	struct wait_queue_entry wait;
+};
+
 struct io_kiocb {
-	struct kiocb		rw;
+	union {
+		struct kiocb		rw;
+		struct io_poll_iocb	poll;
+	};
 
 	struct sqe_submit	submit;
 
@@ -236,6 +249,7 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	init_waitqueue_head(&ctx->wait);
 	spin_lock_init(&ctx->completion_lock);
 	INIT_LIST_HEAD(&ctx->poll_list);
+	INIT_LIST_HEAD(&ctx->cancel_list);
 	return ctx;
 }
 
@@ -989,6 +1003,239 @@ static int io_fsync(struct io_kiocb *req, const struct io_uring_sqe *sqe,
 	return 0;
 }
 
+static void io_poll_remove_one(struct io_kiocb *req)
+{
+	struct io_poll_iocb *poll = &req->poll;
+
+	spin_lock(&poll->head->lock);
+	WRITE_ONCE(poll->canceled, true);
+	if (!list_empty(&poll->wait.entry)) {
+		list_del_init(&poll->wait.entry);
+		queue_work(req->ctx->sqo_wq, &req->work);
+	}
+	spin_unlock(&poll->head->lock);
+
+	list_del_init(&req->list);
+}
+
+static void io_poll_remove_all(struct io_ring_ctx *ctx)
+{
+	struct io_kiocb *req;
+
+	spin_lock_irq(&ctx->completion_lock);
+	while (!list_empty(&ctx->cancel_list)) {
+		req = list_first_entry(&ctx->cancel_list, struct io_kiocb,list);
+		io_poll_remove_one(req);
+	}
+	spin_unlock_irq(&ctx->completion_lock);
+}
+
+/*
+ * Find a running poll command that matches one specified in sqe->addr,
+ * and remove it if found.
+ */
+static int io_poll_remove(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_kiocb *poll_req, *next;
+	int ret = -ENOENT;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->ioprio || sqe->off || sqe->len || sqe->buf_index ||
+	    sqe->poll_events)
+		return -EINVAL;
+
+	spin_lock_irq(&ctx->completion_lock);
+	list_for_each_entry_safe(poll_req, next, &ctx->cancel_list, list) {
+		if (READ_ONCE(sqe->addr) == poll_req->user_data) {
+			io_poll_remove_one(poll_req);
+			ret = 0;
+			break;
+		}
+	}
+	spin_unlock_irq(&ctx->completion_lock);
+
+	io_cqring_add_event(req->ctx, sqe->user_data, ret, 0);
+	io_free_req(req);
+	return 0;
+}
+
+static void io_poll_complete(struct io_kiocb *req, __poll_t mask)
+{
+	io_cqring_add_event(req->ctx, req->user_data, mangle_poll(mask), 0);
+	io_fput(req);
+	io_free_req(req);
+}
+
+static void io_poll_complete_work(struct work_struct *work)
+{
+	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
+	struct io_poll_iocb *poll = &req->poll;
+	struct poll_table_struct pt = { ._key = poll->events };
+	struct io_ring_ctx *ctx = req->ctx;
+	__poll_t mask = 0;
+
+	if (!READ_ONCE(poll->canceled))
+		mask = vfs_poll(poll->file, &pt) & poll->events;
+
+	/*
+	 * Note that ->ki_cancel callers also delete iocb from active_reqs after
+	 * calling ->ki_cancel.  We need the ctx_lock roundtrip here to
+	 * synchronize with them.  In the cancellation case the list_del_init
+	 * itself is not actually needed, but harmless so we keep it in to
+	 * avoid further branches in the fast path.
+	 */
+	spin_lock_irq(&ctx->completion_lock);
+	if (!mask && !READ_ONCE(poll->canceled)) {
+		add_wait_queue(poll->head, &poll->wait);
+		spin_unlock_irq(&ctx->completion_lock);
+		return;
+	}
+	list_del_init(&req->list);
+	spin_unlock_irq(&ctx->completion_lock);
+
+	io_poll_complete(req, mask);
+}
+
+static int io_poll_wake(struct wait_queue_entry *wait, unsigned mode, int sync,
+			void *key)
+{
+	struct io_poll_iocb *poll = container_of(wait, struct io_poll_iocb,
+							wait);
+	struct io_kiocb *req = container_of(poll, struct io_kiocb, poll);
+	struct io_ring_ctx *ctx = req->ctx;
+	__poll_t mask = key_to_poll(key);
+
+	poll->woken = true;
+
+	/* for instances that support it check for an event match first: */
+	if (mask) {
+		if (!(mask & poll->events))
+			return 0;
+
+		/* try to complete the iocb inline if we can: */
+		if (spin_trylock(&ctx->completion_lock)) {
+			list_del(&req->list);
+			spin_unlock(&ctx->completion_lock);
+
+			list_del_init(&poll->wait.entry);
+			io_poll_complete(req, mask);
+			return 1;
+		}
+	}
+
+	list_del_init(&poll->wait.entry);
+	queue_work(ctx->sqo_wq, &req->work);
+	return 1;
+}
+
+struct io_poll_table {
+	struct poll_table_struct pt;
+	struct io_kiocb *req;
+	int error;
+};
+
+static void io_poll_queue_proc(struct file *file, struct wait_queue_head *head,
+			       struct poll_table_struct *p)
+{
+	struct io_poll_table *pt = container_of(p, struct io_poll_table, pt);
+
+	if (unlikely(pt->req->poll.head)) {
+		pt->error = -EINVAL;
+		return;
+	}
+
+	pt->error = 0;
+	pt->req->poll.head = head;
+	add_wait_queue(head, &pt->req->poll.wait);
+}
+
+static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
+{
+	struct io_poll_iocb *poll = &req->poll;
+	struct io_ring_ctx *ctx = req->ctx;
+	struct io_poll_table ipt;
+	unsigned flags;
+	__poll_t mask;
+	u16 events;
+	int fd;
+
+	if (unlikely(req->ctx->flags & IORING_SETUP_IOPOLL))
+		return -EINVAL;
+	if (sqe->addr || sqe->ioprio || sqe->off || sqe->len || sqe->buf_index)
+		return -EINVAL;
+
+	INIT_WORK(&req->work, io_poll_complete_work);
+	events = READ_ONCE(sqe->poll_events);
+	poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP;
+
+	flags = READ_ONCE(sqe->flags);
+	fd = READ_ONCE(sqe->fd);
+
+	if (flags & IOSQE_FIXED_FILE) {
+		if (unlikely(!ctx->user_files || fd >= ctx->user_files->count))
+			return -EBADF;
+		poll->file = ctx->user_files->fp[fd];
+		req->flags |= REQ_F_FIXED_FILE;
+	} else {
+		poll->file = fget(fd);
+	}
+	if (unlikely(!poll->file))
+		return -EBADF;
+
+	poll->head = NULL;
+	poll->woken = false;
+	poll->canceled = false;
+
+	ipt.pt._qproc = io_poll_queue_proc;
+	ipt.pt._key = poll->events;
+	ipt.req = req;
+	ipt.error = -EINVAL; /* same as no support for IOCB_CMD_POLL */
+
+	/* initialized the list so that we can do list_empty checks */
+	INIT_LIST_HEAD(&poll->wait.entry);
+	init_waitqueue_func_entry(&poll->wait, io_poll_wake);
+
+	/* one for removal from waitqueue, one for this function */
+	refcount_set(&req->refs, 2);
+
+	mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
+	if (unlikely(!poll->head)) {
+		/* we did not manage to set up a waitqueue, done */
+		goto out;
+	}
+
+	spin_lock_irq(&ctx->completion_lock);
+	spin_lock(&poll->head->lock);
+	if (poll->woken) {
+		/* wake_up context handles the rest */
+		mask = 0;
+		ipt.error = 0;
+	} else if (mask || ipt.error) {
+		/* if we get an error or a mask we are done */
+		WARN_ON_ONCE(list_empty(&poll->wait.entry));
+		list_del_init(&poll->wait.entry);
+	} else {
+		/* actually waiting for an event */
+		list_add_tail(&req->list, &ctx->cancel_list);
+	}
+	spin_unlock(&poll->head->lock);
+	spin_unlock_irq(&ctx->completion_lock);
+
+out:
+	if (unlikely(ipt.error)) {
+		if (!(flags & IOSQE_FIXED_FILE))
+			fput(poll->file);
+		return ipt.error;
+	}
+
+	if (mask)
+		io_poll_complete(req, mask);
+	io_free_req(req);
+	return 0;
+}
+
 static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 			   const struct sqe_submit *s, bool force_nonblock,
 			   struct io_submit_state *state)
@@ -1024,6 +1271,12 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	case IORING_OP_FSYNC:
 		ret = io_fsync(req, s->sqe, force_nonblock);
 		break;
+	case IORING_OP_POLL_ADD:
+		ret = io_poll_add(req, s->sqe);
+		break;
+	case IORING_OP_POLL_REMOVE:
+		ret = io_poll_remove(req, s->sqe);
+		break;
 	default:
 		ret = -EINVAL;
 		break;
@@ -1933,6 +2186,7 @@ static void io_ring_ctx_wait_and_kill(struct io_ring_ctx *ctx)
 	percpu_ref_kill(&ctx->refs);
 	mutex_unlock(&ctx->uring_lock);
 
+	io_poll_remove_all(ctx);
 	io_iopoll_reap_events(ctx);
 	wait_for_completion(&ctx->ctx_done);
 	io_ring_ctx_free(ctx);
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index 0ec74bab8dbe..e23408692118 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -25,6 +25,7 @@ struct io_uring_sqe {
 	union {
 		__kernel_rwf_t	rw_flags;
 		__u32		fsync_flags;
+		__u16		poll_events;
 	};
 	__u64	user_data;	/* data to be passed back at completion time */
 	union {
@@ -51,6 +52,8 @@ struct io_uring_sqe {
 #define IORING_OP_FSYNC		3
 #define IORING_OP_READ_FIXED	4
 #define IORING_OP_WRITE_FIXED	5
+#define IORING_OP_POLL_ADD	6
+#define IORING_OP_POLL_REMOVE	7
 
 /*
  * sqe->fsync_flags
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 17/18] io_uring: allow workqueue item to handle multiple buffered requests
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (15 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 16/18] io_uring: add support for IORING_OP_POLL Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  2019-02-07 19:55 ` [PATCH 18/18] io_uring: add io_uring_event cache hit information Jens Axboe
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

Right now we punt any buffered request that ends up triggering an
-EAGAIN to an async workqueue. This works fine in terms of providing
async execution of them, but it also can create quite a lot of work
queue items. For sequentially buffered IO, it's advantageous to
serialize the issue of them. For reads, the first one will trigger a
read-ahead, and subsequent request merely end up waiting on later pages
to complete. For writes, devices usually respond better to streamed
sequential writes.

Add state to track the last buffered request we punted to a work queue,
and if the next one is sequential to the previous, attempt to get the
previous work item to handle it. We limit the number of sequential
add-ons to the a multiple (8) of the max read-ahead size of the file.
This should be a good number for both reads and wries, as it defines the
max IO size the device can do directly.

This drastically cuts down on the number of context switches we need to
handle buffered sequential IO, and a basic test case of copying a big
file with io_uring sees a 5x speedup.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c | 267 ++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 216 insertions(+), 51 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index cd456fd65af7..af063145f901 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -72,6 +72,16 @@ struct io_mapped_ubuf {
 	unsigned int	nr_bvecs;
 };
 
+struct async_list {
+	spinlock_t		lock;
+	atomic_t		cnt;
+	struct list_head	list;
+
+	struct file		*file;
+	off_t			io_end;
+	size_t			io_pages;
+};
+
 struct io_ring_ctx {
 	struct {
 		struct percpu_ref	refs;
@@ -140,6 +150,8 @@ struct io_ring_ctx {
 		struct list_head	cancel_list;
 	} ____cacheline_aligned_in_smp;
 
+	struct async_list	pending_async[2];
+
 #if defined(CONFIG_NET)
 	struct socket		*ring_sock;
 #endif
@@ -177,6 +189,7 @@ struct io_kiocb {
 #define REQ_F_FORCE_NONBLOCK	1	/* inline submission attempt */
 #define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
 #define REQ_F_FIXED_FILE	4	/* ctx owns file */
+#define REQ_F_SEQ_PREV		8	/* sequential with previous */
 	u64			user_data;
 	u64			error;
 
@@ -232,6 +245,7 @@ static void io_ring_ctx_ref_free(struct percpu_ref *ref)
 static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 {
 	struct io_ring_ctx *ctx;
+	int i;
 
 	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 	if (!ctx)
@@ -247,6 +261,11 @@ static struct io_ring_ctx *io_ring_ctx_alloc(struct io_uring_params *p)
 	init_completion(&ctx->ctx_done);
 	mutex_init(&ctx->uring_lock);
 	init_waitqueue_head(&ctx->wait);
+	for (i = 0; i < ARRAY_SIZE(ctx->pending_async); i++) {
+		spin_lock_init(&ctx->pending_async[i].lock);
+		INIT_LIST_HEAD(&ctx->pending_async[i].list);
+		atomic_set(&ctx->pending_async[i].cnt, 0);
+	}
 	spin_lock_init(&ctx->completion_lock);
 	INIT_LIST_HEAD(&ctx->poll_list);
 	INIT_LIST_HEAD(&ctx->cancel_list);
@@ -843,6 +862,39 @@ static int io_import_iovec(struct io_ring_ctx *ctx, int rw,
 	return import_iovec(rw, buf, sqe_len, UIO_FASTIOV, iovec, iter);
 }
 
+static void io_async_list_note(int rw, struct io_kiocb *req, size_t len)
+{
+	struct async_list *async_list = &req->ctx->pending_async[rw];
+	struct kiocb *kiocb = &req->rw;
+	struct file *filp = kiocb->ki_filp;
+	off_t io_end = kiocb->ki_pos + len;
+
+	if (filp == async_list->file && kiocb->ki_pos == async_list->io_end) {
+		unsigned long max_pages;
+
+		/* Use 8x RA size as a decent limiter for both reads/writes */
+		max_pages = filp->f_ra.ra_pages;
+		if (!max_pages)
+			max_pages = VM_MAX_READAHEAD >> (PAGE_SHIFT - 10);
+		max_pages *= 8;
+
+		len >>= PAGE_SHIFT;
+		if (async_list->io_pages + len <= max_pages) {
+			req->flags |= REQ_F_SEQ_PREV;
+			async_list->io_pages += len;
+		} else {
+			io_end = 0;
+			async_list->io_pages = 0;
+		}
+	}
+
+	if (async_list->file != filp) {
+		async_list->io_pages = 0;
+		async_list->file = filp;
+	}
+	async_list->io_end = io_end;
+}
+
 static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
 		       bool force_nonblock, struct io_submit_state *state)
 {
@@ -850,6 +902,7 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
 	struct kiocb *kiocb = &req->rw;
 	struct iov_iter iter;
 	struct file *file;
+	size_t iov_count;
 	ssize_t ret;
 
 	ret = io_prep_rw(req, s, force_nonblock, state);
@@ -868,16 +921,24 @@ static ssize_t io_read(struct io_kiocb *req, const struct sqe_submit *s,
 	if (ret)
 		goto out_fput;
 
-	ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_iter_count(&iter));
+	iov_count = iov_iter_count(&iter);
+	ret = rw_verify_area(READ, file, &kiocb->ki_pos, iov_count);
 	if (!ret) {
 		ssize_t ret2;
 
 		/* Catch -EAGAIN return for forced non-blocking submission */
 		ret2 = call_read_iter(file, kiocb, &iter);
-		if (!force_nonblock || ret2 != -EAGAIN)
+		if (!force_nonblock || ret2 != -EAGAIN) {
 			io_rw_done(kiocb, ret2);
-		else
+		} else {
+			/*
+			 * If ->needs_lock is true, we're already in async
+			 * context.
+			 */
+			if (!s->needs_lock)
+				io_async_list_note(READ, req, iov_count);
 			ret = -EAGAIN;
+		}
 	}
 	kfree(iovec);
 out_fput:
@@ -894,14 +955,12 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
 	struct kiocb *kiocb = &req->rw;
 	struct iov_iter iter;
 	struct file *file;
+	size_t iov_count;
 	ssize_t ret;
 
 	ret = io_prep_rw(req, s, force_nonblock, state);
 	if (ret)
 		return ret;
-	/* Hold on to the file for -EAGAIN */
-	if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT))
-		return -EAGAIN;
 
 	ret = -EBADF;
 	file = kiocb->ki_filp;
@@ -915,8 +974,17 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
 	if (ret)
 		goto out_fput;
 
-	ret = rw_verify_area(WRITE, file, &kiocb->ki_pos,
-				iov_iter_count(&iter));
+	iov_count = iov_iter_count(&iter);
+
+	ret = -EAGAIN;
+	if (force_nonblock && !(kiocb->ki_flags & IOCB_DIRECT)) {
+		/* If ->needs_lock is true, we're already in async context. */
+		if (!s->needs_lock)
+			io_async_list_note(WRITE, req, iov_count);
+		goto out_free;
+	}
+
+	ret = rw_verify_area(WRITE, file, &kiocb->ki_pos, iov_count);
 	if (!ret) {
 		/*
 		 * Open-code file_start_write here to grab freeze protection,
@@ -934,9 +1002,11 @@ static ssize_t io_write(struct io_kiocb *req, const struct sqe_submit *s,
 		kiocb->ki_flags |= IOCB_WRITE;
 		io_rw_done(kiocb, call_write_iter(file, kiocb, &iter));
 	}
+out_free:
 	kfree(iovec);
 out_fput:
-	if (unlikely(ret))
+	/* Hold on to the file for -EAGAIN */
+	if (unlikely(ret && ret != -EAGAIN))
 		io_fput(req);
 	return ret;
 }
@@ -1300,6 +1370,21 @@ static int __io_submit_sqe(struct io_ring_ctx *ctx, struct io_kiocb *req,
 	return 0;
 }
 
+static struct async_list *io_async_list_from_sqe(struct io_ring_ctx *ctx,
+						 const struct io_uring_sqe *sqe)
+{
+	switch (sqe->opcode) {
+	case IORING_OP_READV:
+	case IORING_OP_READ_FIXED:
+		return &ctx->pending_async[READ];
+	case IORING_OP_WRITEV:
+	case IORING_OP_WRITE_FIXED:
+		return &ctx->pending_async[WRITE];
+	default:
+		return NULL;
+	}
+}
+
 static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
 {
 	u8 opcode = READ_ONCE(sqe->opcode);
@@ -1311,60 +1396,133 @@ static inline bool io_sqe_needs_user(const struct io_uring_sqe *sqe)
 static void io_sq_wq_submit_work(struct work_struct *work)
 {
 	struct io_kiocb *req = container_of(work, struct io_kiocb, work);
-	struct sqe_submit *s = &req->submit;
 	struct io_ring_ctx *ctx = req->ctx;
+	struct mm_struct *cur_mm = NULL;
+	struct async_list *async_list;
+	LIST_HEAD(req_list);
 	mm_segment_t old_fs;
-	bool needs_user;
-	u64 user_data;
 	int ret;
 
-	 /* Ensure we clear previously set forced non-block flag */
-	req->flags &= ~REQ_F_FORCE_NONBLOCK;
-	req->rw.ki_flags &= ~IOCB_NOWAIT;
+	async_list = io_async_list_from_sqe(ctx, req->submit.sqe);
+restart:
+	do {
+		struct sqe_submit *s = &req->submit;
+		u64 user_data = READ_ONCE(s->sqe->user_data);
+
+		/* Ensure we clear previously set forced non-block flag */
+		req->flags &= ~REQ_F_FORCE_NONBLOCK;
+		req->rw.ki_flags &= ~IOCB_NOWAIT;
 
-	user_data = READ_ONCE(s->sqe->user_data);
-	s->needs_lock = true;
-	s->has_user = false;
-	s->needs_fixed_file = false;
+		ret = 0;
+		if (io_sqe_needs_user(s->sqe) && !cur_mm) {
+			if (!mmget_not_zero(ctx->sqo_mm)) {
+				ret = -EFAULT;
+			} else {
+				cur_mm = ctx->sqo_mm;
+				use_mm(ctx->sqo_mm);
+				old_fs = get_fs();
+				set_fs(USER_DS);
+			}
+		}
+
+		if (!ret) {
+			s->has_user = cur_mm != NULL;
+			s->needs_lock = true;
+			s->needs_fixed_file = false;
+			do {
+				ret = __io_submit_sqe(ctx, req, s, false, NULL);
+				/*
+				 * We can get EAGAIN for polled IO even though
+				 * we're forcing a sync submission from here,
+				 * since we can't wait for request slots on the
+				 * block side.
+				 */
+				if (ret != -EAGAIN)
+					break;
+				cond_resched();
+			} while (1);
+		}
+		if (ret) {
+			io_cqring_add_event(ctx, user_data, ret, 0);
+			io_free_req(req);
+		}
+		if (!async_list)
+			break;
+		if (!list_empty(&req_list)) {
+			req = list_first_entry(&req_list, struct io_kiocb,
+						list);
+			list_del(&req->list);
+			continue;
+		}
+		if (list_empty(&async_list->list))
+			break;
+
+		req = NULL;
+		spin_lock(&async_list->lock);
+		if (list_empty(&async_list->list)) {
+			spin_unlock(&async_list->lock);
+			break;
+		}
+		list_splice_init(&async_list->list, &req_list);
+		spin_unlock(&async_list->lock);
+
+		req = list_first_entry(&req_list, struct io_kiocb, list);
+		list_del(&req->list);
+	} while (req);
 
 	/*
-	 * If we're doing IO to fixed buffers, we don't need to get/set
-	 * user context
+	 * Rare case of racing with a submitter. If we find the count has
+	 * dropped to zero AND we have pending work items, then restart
+	 * the processing. This is a tiny race window.
 	 */
-	needs_user = io_sqe_needs_user(s->sqe);
-	if (needs_user) {
-		if (!mmget_not_zero(ctx->sqo_mm)) {
-			ret = -EFAULT;
-			goto err;
+	ret = atomic_dec_return(&async_list->cnt);
+	while (!ret && !list_empty(&async_list->list)) {
+		spin_lock(&async_list->lock);
+		atomic_inc(&async_list->cnt);
+		list_splice_init(&async_list->list, &req_list);
+		spin_unlock(&async_list->lock);
+
+		if (!list_empty(&req_list)) {
+			req = list_first_entry(&req_list, struct io_kiocb,
+						list);
+			list_del(&req->list);
+			goto restart;
 		}
-		use_mm(ctx->sqo_mm);
-		old_fs = get_fs();
-		set_fs(USER_DS);
-		s->has_user = true;
+		ret = atomic_dec_return(&async_list->cnt);
 	}
 
-	do {
-		ret = __io_submit_sqe(ctx, req, s, false, NULL);
-		/*
-		 * We can get EAGAIN for polled IO even though we're forcing
-		 * a sync submission from here, since we can't wait for
-		 * request slots on the block side.
-		 */
-		if (ret != -EAGAIN)
-			break;
-		cond_resched();
-	} while (1);
-
-	if (needs_user) {
+	if (cur_mm) {
 		set_fs(old_fs);
-		unuse_mm(ctx->sqo_mm);
-		mmput(ctx->sqo_mm);
+		unuse_mm(cur_mm);
+		mmput(cur_mm);
 	}
-err:
-	if (ret) {
-		io_cqring_add_event(ctx, user_data, ret, 0);
-		io_free_req(req);
+}
+
+/*
+ * See if we can piggy back onto previously submitted work, that is still
+ * running. We currently only allow this if the new request is sequential
+ * to the previous one we punted.
+ */
+static bool io_add_to_prev_work(struct async_list *list, struct io_kiocb *req)
+{
+	bool ret = false;
+
+	if (!list)
+		return false;
+	if (!(req->flags & REQ_F_SEQ_PREV))
+		return false;
+	if (!atomic_read(&list->cnt))
+		return false;
+
+	ret = true;
+	spin_lock(&list->lock);
+	list_add_tail(&req->list, &list->list);
+	if (!atomic_read(&list->cnt)) {
+		list_del_init(&req->list);
+		ret = false;
 	}
+	spin_unlock(&list->lock);
+	return ret;
 }
 
 static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s,
@@ -1385,9 +1543,16 @@ static int io_submit_sqe(struct io_ring_ctx *ctx, const struct sqe_submit *s,
 
 	ret = __io_submit_sqe(ctx, req, s, true, state);
 	if (ret == -EAGAIN) {
+		struct async_list *list;
+
+		list = io_async_list_from_sqe(ctx, s->sqe);
 		memcpy(&req->submit, s, sizeof(*s));
-		INIT_WORK(&req->work, io_sq_wq_submit_work);
-		queue_work(ctx->sqo_wq, &req->work);
+		if (!io_add_to_prev_work(list, req)) {
+			if (list)
+				atomic_inc(&list->cnt);
+			INIT_WORK(&req->work, io_sq_wq_submit_work);
+			queue_work(ctx->sqo_wq, &req->work);
+		}
 		ret = 0;
 	}
 	if (ret)
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 18/18] io_uring: add io_uring_event cache hit information
  2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
                   ` (16 preceding siblings ...)
  2019-02-07 19:55 ` [PATCH 17/18] io_uring: allow workqueue item to handle multiple buffered requests Jens Axboe
@ 2019-02-07 19:55 ` Jens Axboe
  17 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 19:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro, Jens Axboe

Add hint on whether a read was served out of the page cache, or if it
hit media. This is useful for buffered async IO, O_DIRECT reads would
never have this set (for obvious reasons).

If the read hit page cache, cqe->flags will have IOCQE_FLAG_CACHEHIT
set.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/io_uring.c                 | 7 ++++++-
 include/uapi/linux/io_uring.h | 5 +++++
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index af063145f901..69ab3f134b6d 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -579,11 +579,16 @@ static void io_fput(struct io_kiocb *req)
 static void io_complete_rw(struct kiocb *kiocb, long res, long res2)
 {
 	struct io_kiocb *req = container_of(kiocb, struct io_kiocb, rw);
+	unsigned ev_flags = 0;
 
 	kiocb_end_write(kiocb);
 
 	io_fput(req);
-	io_cqring_add_event(req->ctx, req->user_data, res, 0);
+
+	if (res > 0 && (req->flags & REQ_F_FORCE_NONBLOCK))
+		ev_flags = IOCQE_FLAG_CACHEHIT;
+
+	io_cqring_add_event(req->ctx, req->user_data, res, ev_flags);
 	io_free_req(req);
 }
 
diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h
index e23408692118..24906e99fdc7 100644
--- a/include/uapi/linux/io_uring.h
+++ b/include/uapi/linux/io_uring.h
@@ -69,6 +69,11 @@ struct io_uring_cqe {
 	__u32	flags;
 };
 
+/*
+ * io_uring_event->flags
+ */
+#define IOCQE_FLAG_CACHEHIT	(1U << 0)	/* IO did not hit media */
+
 /*
  * Magic offsets for the application to mmap the data it needs
  */
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* Re: [PATCH 05/18] Add io_uring IO interface
  2019-02-07 19:55 ` [PATCH 05/18] Add io_uring IO interface Jens Axboe
@ 2019-02-07 20:15   ` Keith Busch
  2019-02-07 20:16     ` Jens Axboe
  0 siblings, 1 reply; 42+ messages in thread
From: Keith Busch @ 2019-02-07 20:15 UTC (permalink / raw)
  To: Jens Axboe
  Cc: linux-aio, linux-block, linux-api, hch, jmoyer, avi, jannh, viro

On Thu, Feb 07, 2019 at 12:55:39PM -0700, Jens Axboe wrote:
> IO submissions use the io_uring_sqe data structure, and completions
> are generated in the form of io_uring_sqe data structures. 
                                        ^^^

Completions use _cqe, right?

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 05/18] Add io_uring IO interface
  2019-02-07 20:15   ` Keith Busch
@ 2019-02-07 20:16     ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 20:16 UTC (permalink / raw)
  To: Keith Busch
  Cc: linux-aio, linux-block, linux-api, hch, jmoyer, avi, jannh, viro

On 2/7/19 1:15 PM, Keith Busch wrote:
> On Thu, Feb 07, 2019 at 12:55:39PM -0700, Jens Axboe wrote:
>> IO submissions use the io_uring_sqe data structure, and completions
>> are generated in the form of io_uring_sqe data structures. 
>                                         ^^^
> 
> Completions use _cqe, right?

They do indeed... Fixed the typo, thanks Keith.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers
  2019-02-07 19:55 ` [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers Jens Axboe
@ 2019-02-07 20:57   ` Jeff Moyer
  2019-02-07 21:02     ` Jens Axboe
  2019-02-07 22:38   ` Jeff Moyer
  1 sibling, 1 reply; 42+ messages in thread
From: Jeff Moyer @ 2019-02-07 20:57 UTC (permalink / raw)
  To: Jens Axboe; +Cc: linux-aio, linux-block, linux-api, hch, avi, jannh, viro

Hi, Jens,

Jens Axboe <axboe@kernel.dk> writes:

> +static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
> +{
> +	int i, j;
> +
> +	if (!ctx->user_bufs)
> +		return -ENXIO;
> +
> +	for (i = 0; i < ctx->sq_entries; i++) {
> +		struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
> +
> +		for (j = 0; j < imu->nr_bvecs; j++)
> +			put_page(imu->bvec[j].bv_page);
> +
> +		io_unaccount_mem(ctx->user, imu->nr_bvecs);
> +		kfree(imu->bvec);
> +		imu->nr_bvecs = 0;
> +	}
> +
> +	kfree(ctx->user_bufs);
> +	ctx->user_bufs = NULL;
> +	free_uid(ctx->user);
        ^^^^^^^^^^^^^^^^^^^
> +	ctx->user = NULL;
        ^^^^^^^^^^^^^^^^^

I don't think you want to do that here.  If you do an
IORING_REGISTER_BUFFERS, followed by IORING_UNREGISTER_BUFFERS, and then
follow that up with IORING_REGISTER_FILES, you'll get a null pointer
dereference trying to bump the reference count of the (now NULL)
ctx->user (io_uring.c:1944):

[  216.927990] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
[  216.935825] #PF error: [WRITE]
[  216.938883] PGD 5f39244067 P4D 5f39244067 PUD 5f043ca067 PMD 0 
[  216.944803] Oops: 0002 [#1] SMP
[  216.947949] CPU: 79 PID: 3371 Comm: io_uring_regist Not tainted 5.0.0-rc5.io_uring.4+ #26
[  216.956119] Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5C620.86B.0D.01.0108.091420182119 09/14/2018
[  216.966553] RIP: 0010:__io_uring_register+0x1c2/0x7c0
[  216.971606] Code: 49 89 c6 48 85 c0 0f 84 9b 05 00 00 48 8b 83 20 02 00 00 48 8b 40 20 49 c7 46 60 60 89 1d 96 49 89 46 18 48 8b 83 18 01 00 00 <f0> ff 00 0f 88 1a a0 52 00 45 31 e4 66 83 7d 00 00 48 89 45 08 7e
[  216.990355] RSP: 0018:ffffb296087e3e70 EFLAGS: 00010286
[  216.995578] RAX: 0000000000000000 RBX: ffff9aacbbff3800 RCX: 0000000000000000
[  217.002711] RDX: ffff9aacbbaf1ac0 RSI: 00000000ffffffff RDI: ffff9aacb9a8f6b0
[  217.009842] RBP: ffff9aacbb45e800 R08: 00000000000000c0 R09: ffff9a4e87c07000
[  217.016977] R10: 0000000000000006 R11: ffff9aac97da9b00 R12: 00007efdc3dbd1fc
[  217.024107] R13: ffff9aacbb45ec08 R14: ffff9aacb9a8f600 R15: ffff9aac97da9a00
[  217.031241] FS:  00007f01c439e500(0000) GS:ffff9aacbf7c0000(0000) knlGS:0000000000000000
[  217.039326] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  217.045075] CR2: 0000000000000000 CR3: 0000005f08d85002 CR4: 00000000007606e0
[  217.052207] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  217.059340] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  217.066472] PKRU: 55555554
[  217.069183] Call Trace:
[  217.071638]  __x64_sys_io_uring_register+0x91/0xb0
[  217.076433]  do_syscall_64+0x4f/0x190
[  217.080110]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
[  217.085167] RIP: 0033:0x7f01c3eb42bd
[  217.088743] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 9b 6b 2c 00 f7 d8 64 89 01 48

I'd expect ctx->user to live as long as the io_uring context itself,
right?

-Jeff

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers
  2019-02-07 20:57   ` Jeff Moyer
@ 2019-02-07 21:02     ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 21:02 UTC (permalink / raw)
  To: Jeff Moyer; +Cc: linux-aio, linux-block, linux-api, hch, avi, jannh, viro

On 2/7/19 1:57 PM, Jeff Moyer wrote:
> Hi, Jens,
> 
> Jens Axboe <axboe@kernel.dk> writes:
> 
>> +static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
>> +{
>> +	int i, j;
>> +
>> +	if (!ctx->user_bufs)
>> +		return -ENXIO;
>> +
>> +	for (i = 0; i < ctx->sq_entries; i++) {
>> +		struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
>> +
>> +		for (j = 0; j < imu->nr_bvecs; j++)
>> +			put_page(imu->bvec[j].bv_page);
>> +
>> +		io_unaccount_mem(ctx->user, imu->nr_bvecs);
>> +		kfree(imu->bvec);
>> +		imu->nr_bvecs = 0;
>> +	}
>> +
>> +	kfree(ctx->user_bufs);
>> +	ctx->user_bufs = NULL;
>> +	free_uid(ctx->user);
>         ^^^^^^^^^^^^^^^^^^^
>> +	ctx->user = NULL;
>         ^^^^^^^^^^^^^^^^^
> 
> I don't think you want to do that here.  If you do an
> IORING_REGISTER_BUFFERS, followed by IORING_UNREGISTER_BUFFERS, and then
> follow that up with IORING_REGISTER_FILES, you'll get a null pointer
> dereference trying to bump the reference count of the (now NULL)
> ctx->user (io_uring.c:1944):
> 
> [  216.927990] BUG: unable to handle kernel NULL pointer dereference at 0000000000000000
> [  216.935825] #PF error: [WRITE]
> [  216.938883] PGD 5f39244067 P4D 5f39244067 PUD 5f043ca067 PMD 0 
> [  216.944803] Oops: 0002 [#1] SMP
> [  216.947949] CPU: 79 PID: 3371 Comm: io_uring_regist Not tainted 5.0.0-rc5.io_uring.4+ #26
> [  216.956119] Hardware name: Intel Corporation S2600WFD/S2600WFD, BIOS SE5C620.86B.0D.01.0108.091420182119 09/14/2018
> [  216.966553] RIP: 0010:__io_uring_register+0x1c2/0x7c0
> [  216.971606] Code: 49 89 c6 48 85 c0 0f 84 9b 05 00 00 48 8b 83 20 02 00 00 48 8b 40 20 49 c7 46 60 60 89 1d 96 49 89 46 18 48 8b 83 18 01 00 00 <f0> ff 00 0f 88 1a a0 52 00 45 31 e4 66 83 7d 00 00 48 89 45 08 7e
> [  216.990355] RSP: 0018:ffffb296087e3e70 EFLAGS: 00010286
> [  216.995578] RAX: 0000000000000000 RBX: ffff9aacbbff3800 RCX: 0000000000000000
> [  217.002711] RDX: ffff9aacbbaf1ac0 RSI: 00000000ffffffff RDI: ffff9aacb9a8f6b0
> [  217.009842] RBP: ffff9aacbb45e800 R08: 00000000000000c0 R09: ffff9a4e87c07000
> [  217.016977] R10: 0000000000000006 R11: ffff9aac97da9b00 R12: 00007efdc3dbd1fc
> [  217.024107] R13: ffff9aacbb45ec08 R14: ffff9aacb9a8f600 R15: ffff9aac97da9a00
> [  217.031241] FS:  00007f01c439e500(0000) GS:ffff9aacbf7c0000(0000) knlGS:0000000000000000
> [  217.039326] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  217.045075] CR2: 0000000000000000 CR3: 0000005f08d85002 CR4: 00000000007606e0
> [  217.052207] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [  217.059340] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [  217.066472] PKRU: 55555554
> [  217.069183] Call Trace:
> [  217.071638]  __x64_sys_io_uring_register+0x91/0xb0
> [  217.076433]  do_syscall_64+0x4f/0x190
> [  217.080110]  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> [  217.085167] RIP: 0033:0x7f01c3eb42bd
> [  217.088743] Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d 9b 6b 2c 00 f7 d8 64 89 01 48
> 
> I'd expect ctx->user to live as long as the io_uring context itself,
> right?

Yes, it used to just be used for the buffers, now we use it generally. I've
fixed that up, thanks Jeff!

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 16/18] io_uring: add support for IORING_OP_POLL
  2019-02-07 19:55 ` [PATCH 16/18] io_uring: add support for IORING_OP_POLL Jens Axboe
@ 2019-02-07 22:12   ` Jeff Moyer
  2019-02-07 22:18     ` Jens Axboe
  0 siblings, 1 reply; 42+ messages in thread
From: Jeff Moyer @ 2019-02-07 22:12 UTC (permalink / raw)
  To: Jens Axboe; +Cc: linux-aio, linux-block, linux-api, hch, avi, jannh, viro

Hi, Jens,

> +static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
> +{

[...]

> +	/* one for removal from waitqueue, one for this function */
> +	refcount_set(&req->refs, 2);
> +
> +	mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
> +	if (unlikely(!poll->head)) {
> +		/* we did not manage to set up a waitqueue, done */
> +		goto out;
> +	}
> +
> +	spin_lock_irq(&ctx->completion_lock);
> +	spin_lock(&poll->head->lock);
> +	if (poll->woken) {
> +		/* wake_up context handles the rest */
> +		mask = 0;
> +		ipt.error = 0;
> +	} else if (mask || ipt.error) {
> +		/* if we get an error or a mask we are done */
> +		WARN_ON_ONCE(list_empty(&poll->wait.entry));
> +		list_del_init(&poll->wait.entry);
> +	} else {
> +		/* actually waiting for an event */
> +		list_add_tail(&req->list, &ctx->cancel_list);
> +	}
> +	spin_unlock(&poll->head->lock);
> +	spin_unlock_irq(&ctx->completion_lock);
> +
> +out:
> +	if (unlikely(ipt.error)) {
> +		if (!(flags & IOSQE_FIXED_FILE))
> +			fput(poll->file);
> +		return ipt.error;
> +	}

You need to drop the reference count on the req inside that if block.

-Jeff

> +
> +	if (mask)
> +		io_poll_complete(req, mask);
> +	io_free_req(req);
> +	return 0;
> +}

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 16/18] io_uring: add support for IORING_OP_POLL
  2019-02-07 22:12   ` Jeff Moyer
@ 2019-02-07 22:18     ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 22:18 UTC (permalink / raw)
  To: Jeff Moyer; +Cc: linux-aio, linux-block, linux-api, hch, avi, jannh, viro

On 2/7/19 3:12 PM, Jeff Moyer wrote:
> Hi, Jens,
> 
>> +static int io_poll_add(struct io_kiocb *req, const struct io_uring_sqe *sqe)
>> +{
> 
> [...]
> 
>> +	/* one for removal from waitqueue, one for this function */
>> +	refcount_set(&req->refs, 2);
>> +
>> +	mask = vfs_poll(poll->file, &ipt.pt) & poll->events;
>> +	if (unlikely(!poll->head)) {
>> +		/* we did not manage to set up a waitqueue, done */
>> +		goto out;
>> +	}
>> +
>> +	spin_lock_irq(&ctx->completion_lock);
>> +	spin_lock(&poll->head->lock);
>> +	if (poll->woken) {
>> +		/* wake_up context handles the rest */
>> +		mask = 0;
>> +		ipt.error = 0;
>> +	} else if (mask || ipt.error) {
>> +		/* if we get an error or a mask we are done */
>> +		WARN_ON_ONCE(list_empty(&poll->wait.entry));
>> +		list_del_init(&poll->wait.entry);
>> +	} else {
>> +		/* actually waiting for an event */
>> +		list_add_tail(&req->list, &ctx->cancel_list);
>> +	}
>> +	spin_unlock(&poll->head->lock);
>> +	spin_unlock_irq(&ctx->completion_lock);
>> +
>> +out:
>> +	if (unlikely(ipt.error)) {
>> +		if (!(flags & IOSQE_FIXED_FILE))
>> +			fput(poll->file);
>> +		return ipt.error;
>> +	}
> 
> You need to drop the reference count on the req inside that if block.

Ah good point, because it's elevated. Fixed, thanks Jeff.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers
  2019-02-07 19:55 ` [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers Jens Axboe
  2019-02-07 20:57   ` Jeff Moyer
@ 2019-02-07 22:38   ` Jeff Moyer
  2019-02-07 22:47     ` Jens Axboe
  1 sibling, 1 reply; 42+ messages in thread
From: Jeff Moyer @ 2019-02-07 22:38 UTC (permalink / raw)
  To: Jens Axboe; +Cc: linux-aio, linux-block, linux-api, hch, avi, jannh, viro

Hi, Jens,

Jens Axboe <axboe@kernel.dk> writes:

> For now, buffers must not be file backed. If file backed buffers are
> passed in, the registration will fail with -1/EOPNOTSUPP. This
> restriction may be relaxed in the future.

[...]

> +		down_write(&current->mm->mmap_sem);
> +		pret = get_user_pages_longterm(ubuf, nr_pages, FOLL_WRITE,
> +						pages, vmas);
> +		if (pret == nr_pages) {
> +			/* don't support file backed memory */
> +			for (j = 0; j < nr_pages; j++) {
> +				struct vm_area_struct *vma = vmas[j];
> +
> +				if (vma->vm_file) {
> +					ret = -EOPNOTSUPP;
> +					break;
> +				}
> +			}

Unfortunately, this suffers the same problem as FOLL_ANON.  Huge pages
are backed by hugetlbfs, and vma->vm_file will be filled in.

I guess you could check is_file_hugepages(vma->vm_file):

        if (vma->vm_file &&
            !is_file_hugepages(vma->vm_file)) {
                ret = -EOPNOTSUPP;
                break;
       }

That works for me.

-Jeff

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers
  2019-02-07 22:38   ` Jeff Moyer
@ 2019-02-07 22:47     ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-07 22:47 UTC (permalink / raw)
  To: Jeff Moyer; +Cc: linux-aio, linux-block, linux-api, hch, avi, jannh, viro

On 2/7/19 3:38 PM, Jeff Moyer wrote:
> Hi, Jens,
> 
> Jens Axboe <axboe@kernel.dk> writes:
> 
>> For now, buffers must not be file backed. If file backed buffers are
>> passed in, the registration will fail with -1/EOPNOTSUPP. This
>> restriction may be relaxed in the future.
> 
> [...]
> 
>> +		down_write(&current->mm->mmap_sem);
>> +		pret = get_user_pages_longterm(ubuf, nr_pages, FOLL_WRITE,
>> +						pages, vmas);
>> +		if (pret == nr_pages) {
>> +			/* don't support file backed memory */
>> +			for (j = 0; j < nr_pages; j++) {
>> +				struct vm_area_struct *vma = vmas[j];
>> +
>> +				if (vma->vm_file) {
>> +					ret = -EOPNOTSUPP;
>> +					break;
>> +				}
>> +			}
> 
> Unfortunately, this suffers the same problem as FOLL_ANON.  Huge pages
> are backed by hugetlbfs, and vma->vm_file will be filled in.
> 
> I guess you could check is_file_hugepages(vma->vm_file):
> 
>         if (vma->vm_file &&
>             !is_file_hugepages(vma->vm_file)) {
>                 ret = -EOPNOTSUPP;
>                 break;
>        }
> 
> That works for me.

Thanks, that looks better. Fixed!

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-07 19:55 ` [PATCH 13/18] io_uring: add file set registration Jens Axboe
@ 2019-02-08 12:17   ` Alan Jenkins
  2019-02-08 12:57     ` Jens Axboe
  0 siblings, 1 reply; 42+ messages in thread
From: Alan Jenkins @ 2019-02-08 12:17 UTC (permalink / raw)
  To: Jens Axboe, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 07/02/2019 19:55, Jens Axboe wrote:
> We normally have to fget/fput for each IO we do on a file. Even with
> the batching we do, the cost of the atomic inc/dec of the file usage
> count adds up.
>
> This adds IORING_REGISTER_FILES, and IORING_UNREGISTER_FILES opcodes
> for the io_uring_register(2) system call. The arguments passed in must
> be an array of __s32 holding file descriptors, and nr_args should hold
> the number of file descriptors the application wishes to pin for the
> duration of the io_uring context (or until IORING_UNREGISTER_FILES is
> called).
>
> When used, the application must set IOSQE_FIXED_FILE in the sqe->flags
> member. Then, instead of setting sqe->fd to the real fd, it sets sqe->fd
> to the index in the array passed in to IORING_REGISTER_FILES.
>
> Files are automatically unregistered when the io_uring context is
> torn down. An application need only unregister if it wishes to
> register a new set of fds.
>
> Signed-off-by: Jens Axboe<axboe@kernel.dk>
> ---
>   fs/io_uring.c                 | 207 +++++++++++++++++++++++++++++-----
>   include/net/af_unix.h         |   1 +
>   include/uapi/linux/io_uring.h |   9 +-
>   net/unix/af_unix.c            |   2 +-
>   4 files changed, 188 insertions(+), 31 deletions(-)
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 9d6233dc35ca..f2550efec60d 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -29,6 +29,7 @@
>   #include <linux/net.h>
>   #include <net/sock.h>
>   #include <net/af_unix.h>
> +#include <net/scm.h>
>   #include <linux/anon_inodes.h>
>   #include <linux/sched/mm.h>
>   #include <linux/uaccess.h>
> @@ -101,6 +102,13 @@ struct io_ring_ctx {
>   		struct fasync_struct	*cq_fasync;
>   	} ____cacheline_aligned_in_smp;
>   
> +	/*
> +	 * If used, fixed file set. Writers must ensure that ->refs is dead,
> +	 * readers must ensure that ->refs is alive as long as the file* is
> +	 * used. Only updated through io_uring_register(2).
> +	 */
> +	struct scm_fp_list	*user_files;
> +
>   	/* if used, fixed mapped user buffers */
>   	unsigned		nr_user_bufs;
>   	struct io_mapped_ubuf	*user_bufs;
> @@ -148,6 +156,7 @@ struct io_kiocb {
>   	unsigned int		flags;
>   #define REQ_F_FORCE_NONBLOCK	1	/* inline submission attempt */
>   #define REQ_F_IOPOLL_COMPLETED	2	/* polled IO has completed */
> +#define REQ_F_FIXED_FILE	4	/* ctx owns file */
>   	u64			user_data;
>   	u64			error;
>   

> +static void __io_sqe_files_unregister(struct io_ring_ctx *ctx)
> +{
> +#if defined(CONFIG_NET)
> +	if (ctx->ring_sock) {
> +		struct sock *sock = ctx->ring_sock->sk;
> +		struct sk_buff *skb;
> +
> +		while ((skb = skb_dequeue(&sock->sk_receive_queue)) != NULL)
> +			kfree_skb(skb);
> +	}
> +#else
> +	int i;
> +
> +	for (i = 0; i < ctx->user_files->count; i++)
> +		fput(ctx->user_files->fp[i]);
> +
> +	kfree(ctx->user_files);
> +#endif
> +}
> +
> +static int io_sqe_files_unregister(struct io_ring_ctx *ctx)
> +{
> +	if (!ctx->user_files)
> +		return -ENXIO;
> +
> +	__io_sqe_files_unregister(ctx);
> +	ctx->user_files = NULL;
> +	return 0;
> +}
> +
> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
> +{
> +#if defined(CONFIG_NET)
> +	struct scm_fp_list *fpl = ctx->user_files;
> +	struct sk_buff *skb;
> +	int i;
> +
> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
> +	if (!skb)
> +		return -ENOMEM;
> +
> +	skb->sk = ctx->ring_sock->sk;
> +	skb->destructor = unix_destruct_scm;
> +
> +	fpl->user = get_uid(ctx->user);
> +	for (i = 0; i < fpl->count; i++) {
> +		get_file(fpl->fp[i]);
> +		unix_inflight(fpl->user, fpl->fp[i]);
> +		fput(fpl->fp[i]);
> +	}
> +
> +	UNIXCB(skb).fp = fpl;
> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);

This code sounds elegant if you know about the existence of unix_gc(), 
but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we 
have a brief comment, to comfort mortal readers on their journey?

/* A message on a unix socket can hold a reference to a file. This can 
cause a reference cycle. So there is a garbage collector for unix 
sockets, which we hook into here. */

I think this is bypassing too_many_unix_fds() though?  I understood that 
was intended to bound kernel memory allocation, at least in principle.

> +#endif

Also, this code relies on CONFIG_NET.  To handle the case where 
CONFIG_NET is not enabled, don't you still need to forbid registering an 
io_uring fd ?

> +	return 0;
> +}
> +
> +static int io_sqe_files_register(struct io_ring_ctx *ctx, void __user *arg,
> +				 unsigned nr_args)
> +{
> +	__s32 __user *fds = (__s32 __user *) arg;
> +	struct scm_fp_list *fpl;
> +	int fd, ret = 0;
> +	unsigned i;
> +
> +	if (ctx->user_files)
> +		return -EBUSY;
> +	if (!nr_args || nr_args > SCM_MAX_FD)
> +		return -EINVAL;
> +
> +	fpl = kzalloc(sizeof(*ctx->user_files), GFP_KERNEL);
> +	if (!fpl)
> +		return -ENOMEM;
> +	fpl->max = nr_args;
> +
> +	for (i = 0; i < nr_args; i++) {
> +		ret = -EFAULT;
> +		if (copy_from_user(&fd, &fds[i], sizeof(fd)))
> +			break;
> +
> +		fpl->fp[i] = fget(fd);
> +
> +		ret = -EBADF;
> +		if (!fpl->fp[i])
> +			break;
> +		fpl->count++;
> +		ret = 0;
> +	}
> +
> +	ctx->user_files = fpl;
> +	if (!ret)
> +		ret = io_sqe_files_scm(ctx);
> +	if (ret)
> +		io_sqe_files_unregister(ctx);
> +
> +	return ret;
> +}
> +
>   static int io_sq_offload_start(struct io_ring_ctx *ctx)
>   {
>   	int ret;
> @@ -1520,14 +1658,16 @@ static void io_ring_ctx_free(struct io_ring_ctx *ctx)
>   		destroy_workqueue(ctx->sqo_wq);
>   	if (ctx->sqo_mm)
>   		mmdrop(ctx->sqo_mm);
> +
> +	io_iopoll_reap_events(ctx);
> +	io_sqe_buffer_unregister(ctx);
> +	io_sqe_files_unregister(ctx);
> +
>   #if defined(CONFIG_NET)
>   	if (ctx->ring_sock)
>   		sock_release(ctx->ring_sock);
>   #endif
>   
> -	io_iopoll_reap_events(ctx);
> -	io_sqe_buffer_unregister(ctx);
> -
>   	io_mem_free(ctx->sq_ring);
>   	io_mem_free(ctx->sq_sqes);
>   	io_mem_free(ctx->cq_ring);
> @@ -1885,6 +2025,15 @@ static int __io_uring_register(struct io_ring_ctx *ctx, unsigned opcode,
>   			break;
>   		ret = io_sqe_buffer_unregister(ctx);
>   		break;
> +	case IORING_REGISTER_FILES:
> +		ret = io_sqe_files_register(ctx, arg, nr_args);
> +		break;
> +	case IORING_UNREGISTER_FILES:
> +		ret = -EINVAL;
> +		if (arg || nr_args)
> +			break;
> +		ret = io_sqe_files_unregister(ctx);
> +		break;
>   	default:
>   		ret = -EINVAL;
>   		break;

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-08 12:17   ` Alan Jenkins
@ 2019-02-08 12:57     ` Jens Axboe
  2019-02-08 14:02       ` Alan Jenkins
  0 siblings, 1 reply; 42+ messages in thread
From: Jens Axboe @ 2019-02-08 12:57 UTC (permalink / raw)
  To: Alan Jenkins, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 2/8/19 5:17 AM, Alan Jenkins wrote:
>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>> +{
>> +#if defined(CONFIG_NET)
>> +	struct scm_fp_list *fpl = ctx->user_files;
>> +	struct sk_buff *skb;
>> +	int i;
>> +
>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>> +	if (!skb)
>> +		return -ENOMEM;
>> +
>> +	skb->sk = ctx->ring_sock->sk;
>> +	skb->destructor = unix_destruct_scm;
>> +
>> +	fpl->user = get_uid(ctx->user);
>> +	for (i = 0; i < fpl->count; i++) {
>> +		get_file(fpl->fp[i]);
>> +		unix_inflight(fpl->user, fpl->fp[i]);
>> +		fput(fpl->fp[i]);
>> +	}
>> +
>> +	UNIXCB(skb).fp = fpl;
>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
> 
> This code sounds elegant if you know about the existence of unix_gc(), 
> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we 
> have a brief comment, to comfort mortal readers on their journey?
> 
> /* A message on a unix socket can hold a reference to a file. This can 
> cause a reference cycle. So there is a garbage collector for unix 
> sockets, which we hook into here. */

Yes that's a good idea, I've added a comment as to why we go through the
trouble of doing this socket + skb dance.

> I think this is bypassing too_many_unix_fds() though?  I understood that 
> was intended to bound kernel memory allocation, at least in principle.

As the code stands above, it'll cap it at 253. I'm just now reworking it
to NOT be limited to the SCM max fd count, but still impose a limit of
1024 on the number of registered files. This is important to cap the
memory allocation attempt as well.

> Also, this code relies on CONFIG_NET.  To handle the case where 
> CONFIG_NET is not enabled, don't you still need to forbid registering an 
> io_uring fd ?

Good point, we do still need to reject the io_uring fd itself if
CONFIG_UNIX is not enabled. Done.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-08 12:57     ` Jens Axboe
@ 2019-02-08 14:02       ` Alan Jenkins
  2019-02-08 15:13         ` Jens Axboe
  0 siblings, 1 reply; 42+ messages in thread
From: Alan Jenkins @ 2019-02-08 14:02 UTC (permalink / raw)
  To: Jens Axboe, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 08/02/2019 12:57, Jens Axboe wrote:
> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>> +{
>>> +#if defined(CONFIG_NET)
>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>> +	struct sk_buff *skb;
>>> +	int i;
>>> +
>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>> +	if (!skb)
>>> +		return -ENOMEM;
>>> +
>>> +	skb->sk = ctx->ring_sock->sk;
>>> +	skb->destructor = unix_destruct_scm;
>>> +
>>> +	fpl->user = get_uid(ctx->user);
>>> +	for (i = 0; i < fpl->count; i++) {
>>> +		get_file(fpl->fp[i]);
>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>> +		fput(fpl->fp[i]);
>>> +	}
>>> +
>>> +	UNIXCB(skb).fp = fpl;
>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>> This code sounds elegant if you know about the existence of unix_gc(),
>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>> have a brief comment, to comfort mortal readers on their journey?
>>
>> /* A message on a unix socket can hold a reference to a file. This can
>> cause a reference cycle. So there is a garbage collector for unix
>> sockets, which we hook into here. */
> Yes that's a good idea, I've added a comment as to why we go through the
> trouble of doing this socket + skb dance.

Great, thanks.

>> I think this is bypassing too_many_unix_fds() though?  I understood that
>> was intended to bound kernel memory allocation, at least in principle.
> As the code stands above, it'll cap it at 253. I'm just now reworking it
> to NOT be limited to the SCM max fd count, but still impose a limit of
> 1024 on the number of registered files. This is important to cap the
> memory allocation attempt as well.

I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand, 
there's no specific limit on the number of io_urings you can open (only 
the standard limits on fds).  So this would let you allocate hundreds of 
times more files than the previous limit RLIMIT_NOFILE...

static inline bool too_many_unix_fds(struct task_struct *p)
{
	struct user_struct *user = current_user();

	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
	return false;
}

RLIMIT_NOFILE is technically per-task, but here it is capping 
unix_inflight per-user.  So the way I look at this, the number of file 
descriptors per user is bounded by NOFILE * NPROC.  Then 
user->unix_inflight can have one additional process' worth (NOFILE) of 
"inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only 
called once per SCM_RIGHTS).

Because io_uring doesn't check too_many_unix_fds(), I think it will let 
you have about 253 (or 1024) more process' worth of open files. That 
could be big proportionally when RLIMIT_NPROC is low.

I don't know if it matters.  It maybe reads like an oversight though.

(If it does matter, it might be cleanest to change too_many_unix_fds() 
to get rid of the "slop".  Since that may be different between af_unix 
and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the 
number of inflight files we want to add.)

>> Also, this code relies on CONFIG_NET.  To handle the case where
>> CONFIG_NET is not enabled, don't you still need to forbid registering an
>> io_uring fd ?
> Good point, we do still need to reject the io_uring fd itself if
> CONFIG_UNIX is not enabled. Done.

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-08 14:02       ` Alan Jenkins
@ 2019-02-08 15:13         ` Jens Axboe
  2019-02-12 12:29           ` Alan Jenkins
  0 siblings, 1 reply; 42+ messages in thread
From: Jens Axboe @ 2019-02-08 15:13 UTC (permalink / raw)
  To: Alan Jenkins, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 2/8/19 7:02 AM, Alan Jenkins wrote:
> On 08/02/2019 12:57, Jens Axboe wrote:
>> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>>> +{
>>>> +#if defined(CONFIG_NET)
>>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>>> +	struct sk_buff *skb;
>>>> +	int i;
>>>> +
>>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>>> +	if (!skb)
>>>> +		return -ENOMEM;
>>>> +
>>>> +	skb->sk = ctx->ring_sock->sk;
>>>> +	skb->destructor = unix_destruct_scm;
>>>> +
>>>> +	fpl->user = get_uid(ctx->user);
>>>> +	for (i = 0; i < fpl->count; i++) {
>>>> +		get_file(fpl->fp[i]);
>>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>>> +		fput(fpl->fp[i]);
>>>> +	}
>>>> +
>>>> +	UNIXCB(skb).fp = fpl;
>>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>>> This code sounds elegant if you know about the existence of unix_gc(),
>>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>>> have a brief comment, to comfort mortal readers on their journey?
>>>
>>> /* A message on a unix socket can hold a reference to a file. This can
>>> cause a reference cycle. So there is a garbage collector for unix
>>> sockets, which we hook into here. */
>> Yes that's a good idea, I've added a comment as to why we go through the
>> trouble of doing this socket + skb dance.
> 
> Great, thanks.
> 
>>> I think this is bypassing too_many_unix_fds() though?  I understood that
>>> was intended to bound kernel memory allocation, at least in principle.
>> As the code stands above, it'll cap it at 253. I'm just now reworking it
>> to NOT be limited to the SCM max fd count, but still impose a limit of
>> 1024 on the number of registered files. This is important to cap the
>> memory allocation attempt as well.
> 
> I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand, 
> there's no specific limit on the number of io_urings you can open (only 
> the standard limits on fds).  So this would let you allocate hundreds of 
> times more files than the previous limit RLIMIT_NOFILE...

But there is, the io_uring itself is under the memlock rlimit.

> static inline bool too_many_unix_fds(struct task_struct *p)
> {
> 	struct user_struct *user = current_user();
> 
> 	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
> 		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
> 	return false;
> }
> 
> RLIMIT_NOFILE is technically per-task, but here it is capping 
> unix_inflight per-user.  So the way I look at this, the number of file 
> descriptors per user is bounded by NOFILE * NPROC.  Then 
> user->unix_inflight can have one additional process' worth (NOFILE) of 
> "inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only 
> called once per SCM_RIGHTS).
> 
> Because io_uring doesn't check too_many_unix_fds(), I think it will let 
> you have about 253 (or 1024) more process' worth of open files. That 
> could be big proportionally when RLIMIT_NPROC is low.
> 
> I don't know if it matters.  It maybe reads like an oversight though.
> 
> (If it does matter, it might be cleanest to change too_many_unix_fds() 
> to get rid of the "slop".  Since that may be different between af_unix 
> and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the 
> number of inflight files we want to add.)

I don't think it matters. The files in the fixed file set have already
been opened by the application, so it counts towards the number of open
files that is allowed to have. I don't think we should impose further
limits on top of that.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-08 15:13         ` Jens Axboe
@ 2019-02-12 12:29           ` Alan Jenkins
  2019-02-12 15:17             ` Jens Axboe
  0 siblings, 1 reply; 42+ messages in thread
From: Alan Jenkins @ 2019-02-12 12:29 UTC (permalink / raw)
  To: Jens Axboe, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 08/02/2019 15:13, Jens Axboe wrote:
> On 2/8/19 7:02 AM, Alan Jenkins wrote:
>> On 08/02/2019 12:57, Jens Axboe wrote:
>>> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>>>> +{
>>>>> +#if defined(CONFIG_NET)
>>>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>>>> +	struct sk_buff *skb;
>>>>> +	int i;
>>>>> +
>>>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>>>> +	if (!skb)
>>>>> +		return -ENOMEM;
>>>>> +
>>>>> +	skb->sk = ctx->ring_sock->sk;
>>>>> +	skb->destructor = unix_destruct_scm;
>>>>> +
>>>>> +	fpl->user = get_uid(ctx->user);
>>>>> +	for (i = 0; i < fpl->count; i++) {
>>>>> +		get_file(fpl->fp[i]);
>>>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>>>> +		fput(fpl->fp[i]);
>>>>> +	}
>>>>> +
>>>>> +	UNIXCB(skb).fp = fpl;
>>>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>>>> This code sounds elegant if you know about the existence of unix_gc(),
>>>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>>>> have a brief comment, to comfort mortal readers on their journey?
>>>>
>>>> /* A message on a unix socket can hold a reference to a file. This can
>>>> cause a reference cycle. So there is a garbage collector for unix
>>>> sockets, which we hook into here. */
>>> Yes that's a good idea, I've added a comment as to why we go through the
>>> trouble of doing this socket + skb dance.
>> Great, thanks.
>>
>>>> I think this is bypassing too_many_unix_fds() though?  I understood that
>>>> was intended to bound kernel memory allocation, at least in principle.
>>> As the code stands above, it'll cap it at 253. I'm just now reworking it
>>> to NOT be limited to the SCM max fd count, but still impose a limit of
>>> 1024 on the number of registered files. This is important to cap the
>>> memory allocation attempt as well.
>> I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand,
>> there's no specific limit on the number of io_urings you can open (only
>> the standard limits on fds).  So this would let you allocate hundreds of
>> times more files than the previous limit RLIMIT_NOFILE...
> But there is, the io_uring itself is under the memlock rlimit.
>
>> static inline bool too_many_unix_fds(struct task_struct *p)
>> {
>> 	struct user_struct *user = current_user();
>>
>> 	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
>> 		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
>> 	return false;
>> }
>>
>> RLIMIT_NOFILE is technically per-task, but here it is capping
>> unix_inflight per-user.  So the way I look at this, the number of file
>> descriptors per user is bounded by NOFILE * NPROC.  Then
>> user->unix_inflight can have one additional process' worth (NOFILE) of
>> "inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only
>> called once per SCM_RIGHTS).
>>
>> Because io_uring doesn't check too_many_unix_fds(), I think it will let
>> you have about 253 (or 1024) more process' worth of open files. That
>> could be big proportionally when RLIMIT_NPROC is low.
>>
>> I don't know if it matters.  It maybe reads like an oversight though.
>>
>> (If it does matter, it might be cleanest to change too_many_unix_fds()
>> to get rid of the "slop".  Since that may be different between af_unix
>> and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the
>> number of inflight files we want to add.)
> I don't think it matters. The files in the fixed file set have already
> been opened by the application, so it counts towards the number of open
> files that is allowed to have. I don't think we should impose further
> limits on top of that.

A process can open one io_uring and 199 other files.  Register the 199 
files in the io_uring, then close their file descriptors.  The main 
NOFILE limit only counts file descriptors.  So then you can open one 
io_uring, 198 other files, and repeat.

You're right, I had forgotten the memlock limit on io_uring.  That makes 
it much less of a practical problem.

But it raises a second point.  It's not just that it lets users allocate 
more files.  You might not want to be limited by user->unix_inflight.  
But you are calling unix_inflight(), which increments it!  Then if 
unix->inflight exceeds the NOFILE limit, you will avoid seeing any 
errors with io_uring, but the user will not be able to send files over 
unix sockets.

So I think this is confusing to read, and confusing to troubleshoot if 
the limit is ever hit.

I would be happy if io_uring didn't increment user->unix_inflight.  I'm 
not sure what the best way is to arrange that.

Regards
Alan

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-12 12:29           ` Alan Jenkins
@ 2019-02-12 15:17             ` Jens Axboe
  2019-02-12 17:21               ` Alan Jenkins
  0 siblings, 1 reply; 42+ messages in thread
From: Jens Axboe @ 2019-02-12 15:17 UTC (permalink / raw)
  To: Alan Jenkins, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 2/12/19 5:29 AM, Alan Jenkins wrote:
> On 08/02/2019 15:13, Jens Axboe wrote:
>> On 2/8/19 7:02 AM, Alan Jenkins wrote:
>>> On 08/02/2019 12:57, Jens Axboe wrote:
>>>> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>>>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>>>>> +{
>>>>>> +#if defined(CONFIG_NET)
>>>>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>>>>> +	struct sk_buff *skb;
>>>>>> +	int i;
>>>>>> +
>>>>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>>>>> +	if (!skb)
>>>>>> +		return -ENOMEM;
>>>>>> +
>>>>>> +	skb->sk = ctx->ring_sock->sk;
>>>>>> +	skb->destructor = unix_destruct_scm;
>>>>>> +
>>>>>> +	fpl->user = get_uid(ctx->user);
>>>>>> +	for (i = 0; i < fpl->count; i++) {
>>>>>> +		get_file(fpl->fp[i]);
>>>>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>>>>> +		fput(fpl->fp[i]);
>>>>>> +	}
>>>>>> +
>>>>>> +	UNIXCB(skb).fp = fpl;
>>>>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>>>>> This code sounds elegant if you know about the existence of unix_gc(),
>>>>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>>>>> have a brief comment, to comfort mortal readers on their journey?
>>>>>
>>>>> /* A message on a unix socket can hold a reference to a file. This can
>>>>> cause a reference cycle. So there is a garbage collector for unix
>>>>> sockets, which we hook into here. */
>>>> Yes that's a good idea, I've added a comment as to why we go through the
>>>> trouble of doing this socket + skb dance.
>>> Great, thanks.
>>>
>>>>> I think this is bypassing too_many_unix_fds() though?  I understood that
>>>>> was intended to bound kernel memory allocation, at least in principle.
>>>> As the code stands above, it'll cap it at 253. I'm just now reworking it
>>>> to NOT be limited to the SCM max fd count, but still impose a limit of
>>>> 1024 on the number of registered files. This is important to cap the
>>>> memory allocation attempt as well.
>>> I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand,
>>> there's no specific limit on the number of io_urings you can open (only
>>> the standard limits on fds).  So this would let you allocate hundreds of
>>> times more files than the previous limit RLIMIT_NOFILE...
>> But there is, the io_uring itself is under the memlock rlimit.
>>
>>> static inline bool too_many_unix_fds(struct task_struct *p)
>>> {
>>> 	struct user_struct *user = current_user();
>>>
>>> 	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
>>> 		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
>>> 	return false;
>>> }
>>>
>>> RLIMIT_NOFILE is technically per-task, but here it is capping
>>> unix_inflight per-user.  So the way I look at this, the number of file
>>> descriptors per user is bounded by NOFILE * NPROC.  Then
>>> user->unix_inflight can have one additional process' worth (NOFILE) of
>>> "inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only
>>> called once per SCM_RIGHTS).
>>>
>>> Because io_uring doesn't check too_many_unix_fds(), I think it will let
>>> you have about 253 (or 1024) more process' worth of open files. That
>>> could be big proportionally when RLIMIT_NPROC is low.
>>>
>>> I don't know if it matters.  It maybe reads like an oversight though.
>>>
>>> (If it does matter, it might be cleanest to change too_many_unix_fds()
>>> to get rid of the "slop".  Since that may be different between af_unix
>>> and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the
>>> number of inflight files we want to add.)
>> I don't think it matters. The files in the fixed file set have already
>> been opened by the application, so it counts towards the number of open
>> files that is allowed to have. I don't think we should impose further
>> limits on top of that.
> 
> A process can open one io_uring and 199 other files.  Register the 199 
> files in the io_uring, then close their file descriptors.  The main 
> NOFILE limit only counts file descriptors.  So then you can open one 
> io_uring, 198 other files, and repeat.
> 
> You're right, I had forgotten the memlock limit on io_uring.  That makes 
> it much less of a practical problem.
> 
> But it raises a second point.  It's not just that it lets users allocate 
> more files.  You might not want to be limited by user->unix_inflight.  
> But you are calling unix_inflight(), which increments it!  Then if 
> unix->inflight exceeds the NOFILE limit, you will avoid seeing any 
> errors with io_uring, but the user will not be able to send files over 
> unix sockets.
> 
> So I think this is confusing to read, and confusing to troubleshoot if 
> the limit is ever hit.
> 
> I would be happy if io_uring didn't increment user->unix_inflight.  I'm 
> not sure what the best way is to arrange that.

How about we just do something like the below? I think that's the saner
approach, rather than bypass user->unix_inflight. It's literally the
same thing.


diff --git a/fs/io_uring.c b/fs/io_uring.c
index a4973af1c272..5196b3aa935e 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2041,6 +2041,13 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
 	struct sk_buff *skb;
 	int i;
 
+	if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
+		struct user_struct *user = ctx->user;
+
+		if (user->unix_inflight > task_rlimit(current, RLIMIT_NOFILE))
+			return -EMFILE;
+	}
+
 	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
 	if (!fpl)
 		return -ENOMEM;


-- 
Jens Axboe


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-12 15:17             ` Jens Axboe
@ 2019-02-12 17:21               ` Alan Jenkins
  2019-02-12 17:33                 ` Jens Axboe
  0 siblings, 1 reply; 42+ messages in thread
From: Alan Jenkins @ 2019-02-12 17:21 UTC (permalink / raw)
  To: Jens Axboe, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 12/02/2019 15:17, Jens Axboe wrote:
> On 2/12/19 5:29 AM, Alan Jenkins wrote:
>> On 08/02/2019 15:13, Jens Axboe wrote:
>>> On 2/8/19 7:02 AM, Alan Jenkins wrote:
>>>> On 08/02/2019 12:57, Jens Axboe wrote:
>>>>> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>>>>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>>>>>> +{
>>>>>>> +#if defined(CONFIG_NET)
>>>>>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>>>>>> +	struct sk_buff *skb;
>>>>>>> +	int i;
>>>>>>> +
>>>>>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>>>>>> +	if (!skb)
>>>>>>> +		return -ENOMEM;
>>>>>>> +
>>>>>>> +	skb->sk = ctx->ring_sock->sk;
>>>>>>> +	skb->destructor = unix_destruct_scm;
>>>>>>> +
>>>>>>> +	fpl->user = get_uid(ctx->user);
>>>>>>> +	for (i = 0; i < fpl->count; i++) {
>>>>>>> +		get_file(fpl->fp[i]);
>>>>>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>>>>>> +		fput(fpl->fp[i]);
>>>>>>> +	}
>>>>>>> +
>>>>>>> +	UNIXCB(skb).fp = fpl;
>>>>>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>>>>>> This code sounds elegant if you know about the existence of unix_gc(),
>>>>>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>>>>>> have a brief comment, to comfort mortal readers on their journey?
>>>>>>
>>>>>> /* A message on a unix socket can hold a reference to a file. This can
>>>>>> cause a reference cycle. So there is a garbage collector for unix
>>>>>> sockets, which we hook into here. */
>>>>> Yes that's a good idea, I've added a comment as to why we go through the
>>>>> trouble of doing this socket + skb dance.
>>>> Great, thanks.
>>>>
>>>>>> I think this is bypassing too_many_unix_fds() though?  I understood that
>>>>>> was intended to bound kernel memory allocation, at least in principle.
>>>>> As the code stands above, it'll cap it at 253. I'm just now reworking it
>>>>> to NOT be limited to the SCM max fd count, but still impose a limit of
>>>>> 1024 on the number of registered files. This is important to cap the
>>>>> memory allocation attempt as well.
>>>> I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand,
>>>> there's no specific limit on the number of io_urings you can open (only
>>>> the standard limits on fds).  So this would let you allocate hundreds of
>>>> times more files than the previous limit RLIMIT_NOFILE...
>>> But there is, the io_uring itself is under the memlock rlimit.
>>>
>>>> static inline bool too_many_unix_fds(struct task_struct *p)
>>>> {
>>>> 	struct user_struct *user = current_user();
>>>>
>>>> 	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
>>>> 		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
>>>> 	return false;
>>>> }
>>>>
>>>> RLIMIT_NOFILE is technically per-task, but here it is capping
>>>> unix_inflight per-user.  So the way I look at this, the number of file
>>>> descriptors per user is bounded by NOFILE * NPROC.  Then
>>>> user->unix_inflight can have one additional process' worth (NOFILE) of
>>>> "inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only
>>>> called once per SCM_RIGHTS).
>>>>
>>>> Because io_uring doesn't check too_many_unix_fds(), I think it will let
>>>> you have about 253 (or 1024) more process' worth of open files. That
>>>> could be big proportionally when RLIMIT_NPROC is low.
>>>>
>>>> I don't know if it matters.  It maybe reads like an oversight though.
>>>>
>>>> (If it does matter, it might be cleanest to change too_many_unix_fds()
>>>> to get rid of the "slop".  Since that may be different between af_unix
>>>> and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the
>>>> number of inflight files we want to add.)
>>> I don't think it matters. The files in the fixed file set have already
>>> been opened by the application, so it counts towards the number of open
>>> files that is allowed to have. I don't think we should impose further
>>> limits on top of that.
>> A process can open one io_uring and 199 other files.  Register the 199
>> files in the io_uring, then close their file descriptors.  The main
>> NOFILE limit only counts file descriptors.  So then you can open one
>> io_uring, 198 other files, and repeat.
>>
>> You're right, I had forgotten the memlock limit on io_uring.  That makes
>> it much less of a practical problem.
>>
>> But it raises a second point.  It's not just that it lets users allocate
>> more files.  You might not want to be limited by user->unix_inflight.
>> But you are calling unix_inflight(), which increments it!  Then if
>> unix->inflight exceeds the NOFILE limit, you will avoid seeing any
>> errors with io_uring, but the user will not be able to send files over
>> unix sockets.
>>
>> So I think this is confusing to read, and confusing to troubleshoot if
>> the limit is ever hit.
>>
>> I would be happy if io_uring didn't increment user->unix_inflight.  I'm
>> not sure what the best way is to arrange that.
> How about we just do something like the below? I think that's the saner
> approach, rather than bypass user->unix_inflight. It's literally the
> same thing.
>
>
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index a4973af1c272..5196b3aa935e 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2041,6 +2041,13 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
>   	struct sk_buff *skb;
>   	int i;
>   
> +	if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
> +		struct user_struct *user = ctx->user;
> +
> +		if (user->unix_inflight > task_rlimit(current, RLIMIT_NOFILE))
> +			return -EMFILE;
> +	}
> +
>   	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
>   	if (!fpl)
>   		return -ENOMEM;
>
>

Welp, you gave me exactly what I asked for.  So now I'd better be 
positive about it :-D.

I hope this will be documented accurately, at least where the EMFILE 
result is explained for this syscall.

Because EMFILE is different from the errno in af_unix.c, I will add a 
wish for the existing documentation of ETOOMANYREFS in unix(7) to 
reference this.

I'll stop bikeshedding there.  EMFILE sounds ok.  strerror() calls 
ETOOMANYREFS "Too many references: cannot splice"; it doesn't seem to be 
particularly helpful or well-known.

Thanks
Alan

^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-12 17:21               ` Alan Jenkins
@ 2019-02-12 17:33                 ` Jens Axboe
  2019-02-12 20:23                   ` Alan Jenkins
  0 siblings, 1 reply; 42+ messages in thread
From: Jens Axboe @ 2019-02-12 17:33 UTC (permalink / raw)
  To: Alan Jenkins, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 2/12/19 10:21 AM, Alan Jenkins wrote:
> On 12/02/2019 15:17, Jens Axboe wrote:
>> On 2/12/19 5:29 AM, Alan Jenkins wrote:
>>> On 08/02/2019 15:13, Jens Axboe wrote:
>>>> On 2/8/19 7:02 AM, Alan Jenkins wrote:
>>>>> On 08/02/2019 12:57, Jens Axboe wrote:
>>>>>> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>>>>>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>>>>>>> +{
>>>>>>>> +#if defined(CONFIG_NET)
>>>>>>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>>>>>>> +	struct sk_buff *skb;
>>>>>>>> +	int i;
>>>>>>>> +
>>>>>>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>>>>>>> +	if (!skb)
>>>>>>>> +		return -ENOMEM;
>>>>>>>> +
>>>>>>>> +	skb->sk = ctx->ring_sock->sk;
>>>>>>>> +	skb->destructor = unix_destruct_scm;
>>>>>>>> +
>>>>>>>> +	fpl->user = get_uid(ctx->user);
>>>>>>>> +	for (i = 0; i < fpl->count; i++) {
>>>>>>>> +		get_file(fpl->fp[i]);
>>>>>>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>>>>>>> +		fput(fpl->fp[i]);
>>>>>>>> +	}
>>>>>>>> +
>>>>>>>> +	UNIXCB(skb).fp = fpl;
>>>>>>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>>>>>>> This code sounds elegant if you know about the existence of unix_gc(),
>>>>>>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>>>>>>> have a brief comment, to comfort mortal readers on their journey?
>>>>>>>
>>>>>>> /* A message on a unix socket can hold a reference to a file. This can
>>>>>>> cause a reference cycle. So there is a garbage collector for unix
>>>>>>> sockets, which we hook into here. */
>>>>>> Yes that's a good idea, I've added a comment as to why we go through the
>>>>>> trouble of doing this socket + skb dance.
>>>>> Great, thanks.
>>>>>
>>>>>>> I think this is bypassing too_many_unix_fds() though?  I understood that
>>>>>>> was intended to bound kernel memory allocation, at least in principle.
>>>>>> As the code stands above, it'll cap it at 253. I'm just now reworking it
>>>>>> to NOT be limited to the SCM max fd count, but still impose a limit of
>>>>>> 1024 on the number of registered files. This is important to cap the
>>>>>> memory allocation attempt as well.
>>>>> I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand,
>>>>> there's no specific limit on the number of io_urings you can open (only
>>>>> the standard limits on fds).  So this would let you allocate hundreds of
>>>>> times more files than the previous limit RLIMIT_NOFILE...
>>>> But there is, the io_uring itself is under the memlock rlimit.
>>>>
>>>>> static inline bool too_many_unix_fds(struct task_struct *p)
>>>>> {
>>>>> 	struct user_struct *user = current_user();
>>>>>
>>>>> 	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
>>>>> 		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
>>>>> 	return false;
>>>>> }
>>>>>
>>>>> RLIMIT_NOFILE is technically per-task, but here it is capping
>>>>> unix_inflight per-user.  So the way I look at this, the number of file
>>>>> descriptors per user is bounded by NOFILE * NPROC.  Then
>>>>> user->unix_inflight can have one additional process' worth (NOFILE) of
>>>>> "inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only
>>>>> called once per SCM_RIGHTS).
>>>>>
>>>>> Because io_uring doesn't check too_many_unix_fds(), I think it will let
>>>>> you have about 253 (or 1024) more process' worth of open files. That
>>>>> could be big proportionally when RLIMIT_NPROC is low.
>>>>>
>>>>> I don't know if it matters.  It maybe reads like an oversight though.
>>>>>
>>>>> (If it does matter, it might be cleanest to change too_many_unix_fds()
>>>>> to get rid of the "slop".  Since that may be different between af_unix
>>>>> and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the
>>>>> number of inflight files we want to add.)
>>>> I don't think it matters. The files in the fixed file set have already
>>>> been opened by the application, so it counts towards the number of open
>>>> files that is allowed to have. I don't think we should impose further
>>>> limits on top of that.
>>> A process can open one io_uring and 199 other files.  Register the 199
>>> files in the io_uring, then close their file descriptors.  The main
>>> NOFILE limit only counts file descriptors.  So then you can open one
>>> io_uring, 198 other files, and repeat.
>>>
>>> You're right, I had forgotten the memlock limit on io_uring.  That makes
>>> it much less of a practical problem.
>>>
>>> But it raises a second point.  It's not just that it lets users allocate
>>> more files.  You might not want to be limited by user->unix_inflight.
>>> But you are calling unix_inflight(), which increments it!  Then if
>>> unix->inflight exceeds the NOFILE limit, you will avoid seeing any
>>> errors with io_uring, but the user will not be able to send files over
>>> unix sockets.
>>>
>>> So I think this is confusing to read, and confusing to troubleshoot if
>>> the limit is ever hit.
>>>
>>> I would be happy if io_uring didn't increment user->unix_inflight.  I'm
>>> not sure what the best way is to arrange that.
>> How about we just do something like the below? I think that's the saner
>> approach, rather than bypass user->unix_inflight. It's literally the
>> same thing.
>>
>>
>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>> index a4973af1c272..5196b3aa935e 100644
>> --- a/fs/io_uring.c
>> +++ b/fs/io_uring.c
>> @@ -2041,6 +2041,13 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
>>   	struct sk_buff *skb;
>>   	int i;
>>   
>> +	if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
>> +		struct user_struct *user = ctx->user;
>> +
>> +		if (user->unix_inflight > task_rlimit(current, RLIMIT_NOFILE))
>> +			return -EMFILE;
>> +	}
>> +
>>   	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
>>   	if (!fpl)
>>   		return -ENOMEM;
>>
>>
> 
> Welp, you gave me exactly what I asked for.  So now I'd better be 
> positive about it :-D.

;-)

> I hope this will be documented accurately, at least where the EMFILE 
> result is explained for this syscall.

How's this:

http://git.kernel.dk/cgit/liburing/commit/?id=37e48698a09aa1e37690f8fa6dfd8da69a48ee60

> Because EMFILE is different from the errno in af_unix.c, I will add a 
> wish for the existing documentation of ETOOMANYREFS in unix(7) to 
> reference this.
> 
> I'll stop bikeshedding there.  EMFILE sounds ok.  strerror() calls 
> ETOOMANYREFS "Too many references: cannot splice"; it doesn't seem to be 
> particularly helpful or well-known.

Agree

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-12 17:33                 ` Jens Axboe
@ 2019-02-12 20:23                   ` Alan Jenkins
  2019-02-12 21:10                     ` Jens Axboe
  0 siblings, 1 reply; 42+ messages in thread
From: Alan Jenkins @ 2019-02-12 20:23 UTC (permalink / raw)
  To: Jens Axboe, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 12/02/2019 17:33, Jens Axboe wrote:
> On 2/12/19 10:21 AM, Alan Jenkins wrote:
>> On 12/02/2019 15:17, Jens Axboe wrote:
>>> On 2/12/19 5:29 AM, Alan Jenkins wrote:
>>>> On 08/02/2019 15:13, Jens Axboe wrote:
>>>>> On 2/8/19 7:02 AM, Alan Jenkins wrote:
>>>>>> On 08/02/2019 12:57, Jens Axboe wrote:
>>>>>>> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>>>>>>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>>>>>>>> +{
>>>>>>>>> +#if defined(CONFIG_NET)
>>>>>>>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>>>>>>>> +	struct sk_buff *skb;
>>>>>>>>> +	int i;
>>>>>>>>> +
>>>>>>>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>>>>>>>> +	if (!skb)
>>>>>>>>> +		return -ENOMEM;
>>>>>>>>> +
>>>>>>>>> +	skb->sk = ctx->ring_sock->sk;
>>>>>>>>> +	skb->destructor = unix_destruct_scm;
>>>>>>>>> +
>>>>>>>>> +	fpl->user = get_uid(ctx->user);
>>>>>>>>> +	for (i = 0; i < fpl->count; i++) {
>>>>>>>>> +		get_file(fpl->fp[i]);
>>>>>>>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>>>>>>>> +		fput(fpl->fp[i]);
>>>>>>>>> +	}
>>>>>>>>> +
>>>>>>>>> +	UNIXCB(skb).fp = fpl;
>>>>>>>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>>>>>>>> This code sounds elegant if you know about the existence of unix_gc(),
>>>>>>>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>>>>>>>> have a brief comment, to comfort mortal readers on their journey?
>>>>>>>>
>>>>>>>> /* A message on a unix socket can hold a reference to a file. This can
>>>>>>>> cause a reference cycle. So there is a garbage collector for unix
>>>>>>>> sockets, which we hook into here. */
>>>>>>> Yes that's a good idea, I've added a comment as to why we go through the
>>>>>>> trouble of doing this socket + skb dance.
>>>>>> Great, thanks.
>>>>>>
>>>>>>>> I think this is bypassing too_many_unix_fds() though?  I understood that
>>>>>>>> was intended to bound kernel memory allocation, at least in principle.
>>>>>>> As the code stands above, it'll cap it at 253. I'm just now reworking it
>>>>>>> to NOT be limited to the SCM max fd count, but still impose a limit of
>>>>>>> 1024 on the number of registered files. This is important to cap the
>>>>>>> memory allocation attempt as well.
>>>>>> I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand,
>>>>>> there's no specific limit on the number of io_urings you can open (only
>>>>>> the standard limits on fds).  So this would let you allocate hundreds of
>>>>>> times more files than the previous limit RLIMIT_NOFILE...
>>>>> But there is, the io_uring itself is under the memlock rlimit.
>>>>>
>>>>>> static inline bool too_many_unix_fds(struct task_struct *p)
>>>>>> {
>>>>>> 	struct user_struct *user = current_user();
>>>>>>
>>>>>> 	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
>>>>>> 		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
>>>>>> 	return false;
>>>>>> }
>>>>>>
>>>>>> RLIMIT_NOFILE is technically per-task, but here it is capping
>>>>>> unix_inflight per-user.  So the way I look at this, the number of file
>>>>>> descriptors per user is bounded by NOFILE * NPROC.  Then
>>>>>> user->unix_inflight can have one additional process' worth (NOFILE) of
>>>>>> "inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only
>>>>>> called once per SCM_RIGHTS).
>>>>>>
>>>>>> Because io_uring doesn't check too_many_unix_fds(), I think it will let
>>>>>> you have about 253 (or 1024) more process' worth of open files. That
>>>>>> could be big proportionally when RLIMIT_NPROC is low.
>>>>>>
>>>>>> I don't know if it matters.  It maybe reads like an oversight though.
>>>>>>
>>>>>> (If it does matter, it might be cleanest to change too_many_unix_fds()
>>>>>> to get rid of the "slop".  Since that may be different between af_unix
>>>>>> and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the
>>>>>> number of inflight files we want to add.)
>>>>> I don't think it matters. The files in the fixed file set have already
>>>>> been opened by the application, so it counts towards the number of open
>>>>> files that is allowed to have. I don't think we should impose further
>>>>> limits on top of that.
>>>> A process can open one io_uring and 199 other files.  Register the 199
>>>> files in the io_uring, then close their file descriptors.  The main
>>>> NOFILE limit only counts file descriptors.  So then you can open one
>>>> io_uring, 198 other files, and repeat.
>>>>
>>>> You're right, I had forgotten the memlock limit on io_uring.  That makes
>>>> it much less of a practical problem.
>>>>
>>>> But it raises a second point.  It's not just that it lets users allocate
>>>> more files.  You might not want to be limited by user->unix_inflight.
>>>> But you are calling unix_inflight(), which increments it!  Then if
>>>> unix->inflight exceeds the NOFILE limit, you will avoid seeing any
>>>> errors with io_uring, but the user will not be able to send files over
>>>> unix sockets.
>>>>
>>>> So I think this is confusing to read, and confusing to troubleshoot if
>>>> the limit is ever hit.
>>>>
>>>> I would be happy if io_uring didn't increment user->unix_inflight.  I'm
>>>> not sure what the best way is to arrange that.
>>> How about we just do something like the below? I think that's the saner
>>> approach, rather than bypass user->unix_inflight. It's literally the
>>> same thing.
>>>
>>>
>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>> index a4973af1c272..5196b3aa935e 100644
>>> --- a/fs/io_uring.c
>>> +++ b/fs/io_uring.c
>>> @@ -2041,6 +2041,13 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
>>>    	struct sk_buff *skb;
>>>    	int i;
>>>    
>>> +	if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
>>> +		struct user_struct *user = ctx->user;
>>> +
>>> +		if (user->unix_inflight > task_rlimit(current, RLIMIT_NOFILE))
>>> +			return -EMFILE;
>>> +	}
>>> +
>>>    	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
>>>    	if (!fpl)
>>>    		return -ENOMEM;
>>>
>>>
>> Welp, you gave me exactly what I asked for.  So now I'd better be
>> positive about it :-D.
> ;-)
>
>> I hope this will be documented accurately, at least where the EMFILE
>> result is explained for this syscall.
> How's this:
>
> http://git.kernel.dk/cgit/liburing/commit/?id=37e48698a09aa1e37690f8fa6dfd8da69a48ee60

+.B EMFILE
+.BR IORING_REGISTER_FILES
+was specified and adding
+.I nr_args
+file references would exceed the maximum allowed number of files the process
+is allowed to have according to the
+.B
+RLIMIT_NOFILE
+resource limit and the caller does not have
+.B CAP_SYS_RESOURCE
+capability.
+.TP

I was struggling with this.  The POSIX part of RLIMIT_NOFILE is applied 
per-process.  But the part we're talking about here, the Linux-specific 
"unix_inflight" resource, is actually accounted per-user.  It's like 
RLIMIT_NPROC.  The value of RLIMIT_NPROC is per-process, but the 
resource it limits is counted in user->processes.

This subtlety of the NOFILE limit is not made clear in the text above, 
nor in unix(7), nor in getrlimit(2).  I would interpret all these docs 
as saying this limit is a per-process thing - I think they are misleading.

IORING_MAX_FIXED_FILES is being raised to 1024, which is the same as the 
(soft limit) value for RLIMIT_NOFILE which the kernel sets for the init 
process.  I have an unjustifiable nervousness, that there will be some 
`fio` command, or a test written that maxes out IORING_REGISTER_FILES.  
When you do that, it will provoke unexpected failures e.g. in GUI apps.  
If we can't rule that out, the next best thing is a friendly man page.

Regards
Alan

>> Because EMFILE is different from the errno in af_unix.c, I will add a
>> wish for the existing documentation of ETOOMANYREFS in unix(7) to
>> reference this.
>>
>> I'll stop bikeshedding there.  EMFILE sounds ok.  strerror() calls
>> ETOOMANYREFS "Too many references: cannot splice"; it doesn't seem to be
>> particularly helpful or well-known.
> Agree
>


^ permalink raw reply	[flat|nested] 42+ messages in thread

* Re: [PATCH 13/18] io_uring: add file set registration
  2019-02-12 20:23                   ` Alan Jenkins
@ 2019-02-12 21:10                     ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-12 21:10 UTC (permalink / raw)
  To: Alan Jenkins, linux-aio, linux-block, linux-api
  Cc: hch, jmoyer, avi, jannh, viro

On 2/12/19 1:23 PM, Alan Jenkins wrote:
> On 12/02/2019 17:33, Jens Axboe wrote:
>> On 2/12/19 10:21 AM, Alan Jenkins wrote:
>>> On 12/02/2019 15:17, Jens Axboe wrote:
>>>> On 2/12/19 5:29 AM, Alan Jenkins wrote:
>>>>> On 08/02/2019 15:13, Jens Axboe wrote:
>>>>>> On 2/8/19 7:02 AM, Alan Jenkins wrote:
>>>>>>> On 08/02/2019 12:57, Jens Axboe wrote:
>>>>>>>> On 2/8/19 5:17 AM, Alan Jenkins wrote:
>>>>>>>>>> +static int io_sqe_files_scm(struct io_ring_ctx *ctx)
>>>>>>>>>> +{
>>>>>>>>>> +#if defined(CONFIG_NET)
>>>>>>>>>> +	struct scm_fp_list *fpl = ctx->user_files;
>>>>>>>>>> +	struct sk_buff *skb;
>>>>>>>>>> +	int i;
>>>>>>>>>> +
>>>>>>>>>> +	skb =  __alloc_skb(0, GFP_KERNEL, 0, NUMA_NO_NODE);
>>>>>>>>>> +	if (!skb)
>>>>>>>>>> +		return -ENOMEM;
>>>>>>>>>> +
>>>>>>>>>> +	skb->sk = ctx->ring_sock->sk;
>>>>>>>>>> +	skb->destructor = unix_destruct_scm;
>>>>>>>>>> +
>>>>>>>>>> +	fpl->user = get_uid(ctx->user);
>>>>>>>>>> +	for (i = 0; i < fpl->count; i++) {
>>>>>>>>>> +		get_file(fpl->fp[i]);
>>>>>>>>>> +		unix_inflight(fpl->user, fpl->fp[i]);
>>>>>>>>>> +		fput(fpl->fp[i]);
>>>>>>>>>> +	}
>>>>>>>>>> +
>>>>>>>>>> +	UNIXCB(skb).fp = fpl;
>>>>>>>>>> +	skb_queue_head(&ctx->ring_sock->sk->sk_receive_queue, skb);
>>>>>>>>> This code sounds elegant if you know about the existence of unix_gc(),
>>>>>>>>> but quite mysterious if you don't.  (E.g. why "inflight"?)  Could we
>>>>>>>>> have a brief comment, to comfort mortal readers on their journey?
>>>>>>>>>
>>>>>>>>> /* A message on a unix socket can hold a reference to a file. This can
>>>>>>>>> cause a reference cycle. So there is a garbage collector for unix
>>>>>>>>> sockets, which we hook into here. */
>>>>>>>> Yes that's a good idea, I've added a comment as to why we go through the
>>>>>>>> trouble of doing this socket + skb dance.
>>>>>>> Great, thanks.
>>>>>>>
>>>>>>>>> I think this is bypassing too_many_unix_fds() though?  I understood that
>>>>>>>>> was intended to bound kernel memory allocation, at least in principle.
>>>>>>>> As the code stands above, it'll cap it at 253. I'm just now reworking it
>>>>>>>> to NOT be limited to the SCM max fd count, but still impose a limit of
>>>>>>>> 1024 on the number of registered files. This is important to cap the
>>>>>>>> memory allocation attempt as well.
>>>>>>> I saw you were limiting to SCM_MAX_FD per io_uring.  On the other hand,
>>>>>>> there's no specific limit on the number of io_urings you can open (only
>>>>>>> the standard limits on fds).  So this would let you allocate hundreds of
>>>>>>> times more files than the previous limit RLIMIT_NOFILE...
>>>>>> But there is, the io_uring itself is under the memlock rlimit.
>>>>>>
>>>>>>> static inline bool too_many_unix_fds(struct task_struct *p)
>>>>>>> {
>>>>>>> 	struct user_struct *user = current_user();
>>>>>>>
>>>>>>> 	if (unlikely(user->unix_inflight > task_rlimit(p, RLIMIT_NOFILE)))
>>>>>>> 		return !capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN);
>>>>>>> 	return false;
>>>>>>> }
>>>>>>>
>>>>>>> RLIMIT_NOFILE is technically per-task, but here it is capping
>>>>>>> unix_inflight per-user.  So the way I look at this, the number of file
>>>>>>> descriptors per user is bounded by NOFILE * NPROC.  Then
>>>>>>> user->unix_inflight can have one additional process' worth (NOFILE) of
>>>>>>> "inflight" files.  (Plus SCM_MAX_FD slop, because too_many_fds() is only
>>>>>>> called once per SCM_RIGHTS).
>>>>>>>
>>>>>>> Because io_uring doesn't check too_many_unix_fds(), I think it will let
>>>>>>> you have about 253 (or 1024) more process' worth of open files. That
>>>>>>> could be big proportionally when RLIMIT_NPROC is low.
>>>>>>>
>>>>>>> I don't know if it matters.  It maybe reads like an oversight though.
>>>>>>>
>>>>>>> (If it does matter, it might be cleanest to change too_many_unix_fds()
>>>>>>> to get rid of the "slop".  Since that may be different between af_unix
>>>>>>> and io_uring; 253 v.s. 1024 or whatever. E.g. add a parameter for the
>>>>>>> number of inflight files we want to add.)
>>>>>> I don't think it matters. The files in the fixed file set have already
>>>>>> been opened by the application, so it counts towards the number of open
>>>>>> files that is allowed to have. I don't think we should impose further
>>>>>> limits on top of that.
>>>>> A process can open one io_uring and 199 other files.  Register the 199
>>>>> files in the io_uring, then close their file descriptors.  The main
>>>>> NOFILE limit only counts file descriptors.  So then you can open one
>>>>> io_uring, 198 other files, and repeat.
>>>>>
>>>>> You're right, I had forgotten the memlock limit on io_uring.  That makes
>>>>> it much less of a practical problem.
>>>>>
>>>>> But it raises a second point.  It's not just that it lets users allocate
>>>>> more files.  You might not want to be limited by user->unix_inflight.
>>>>> But you are calling unix_inflight(), which increments it!  Then if
>>>>> unix->inflight exceeds the NOFILE limit, you will avoid seeing any
>>>>> errors with io_uring, but the user will not be able to send files over
>>>>> unix sockets.
>>>>>
>>>>> So I think this is confusing to read, and confusing to troubleshoot if
>>>>> the limit is ever hit.
>>>>>
>>>>> I would be happy if io_uring didn't increment user->unix_inflight.  I'm
>>>>> not sure what the best way is to arrange that.
>>>> How about we just do something like the below? I think that's the saner
>>>> approach, rather than bypass user->unix_inflight. It's literally the
>>>> same thing.
>>>>
>>>>
>>>> diff --git a/fs/io_uring.c b/fs/io_uring.c
>>>> index a4973af1c272..5196b3aa935e 100644
>>>> --- a/fs/io_uring.c
>>>> +++ b/fs/io_uring.c
>>>> @@ -2041,6 +2041,13 @@ static int __io_sqe_files_scm(struct io_ring_ctx *ctx, int nr, int offset)
>>>>    	struct sk_buff *skb;
>>>>    	int i;
>>>>    
>>>> +	if (!capable(CAP_SYS_RESOURCE) && !capable(CAP_SYS_ADMIN)) {
>>>> +		struct user_struct *user = ctx->user;
>>>> +
>>>> +		if (user->unix_inflight > task_rlimit(current, RLIMIT_NOFILE))
>>>> +			return -EMFILE;
>>>> +	}
>>>> +
>>>>    	fpl = kzalloc(sizeof(*fpl), GFP_KERNEL);
>>>>    	if (!fpl)
>>>>    		return -ENOMEM;
>>>>
>>>>
>>> Welp, you gave me exactly what I asked for.  So now I'd better be
>>> positive about it :-D.
>> ;-)
>>
>>> I hope this will be documented accurately, at least where the EMFILE
>>> result is explained for this syscall.
>> How's this:
>>
>> http://git.kernel.dk/cgit/liburing/commit/?id=37e48698a09aa1e37690f8fa6dfd8da69a48ee60
> 
> +.B EMFILE
> +.BR IORING_REGISTER_FILES
> +was specified and adding
> +.I nr_args
> +file references would exceed the maximum allowed number of files the process
> +is allowed to have according to the
> +.B
> +RLIMIT_NOFILE
> +resource limit and the caller does not have
> +.B CAP_SYS_RESOURCE
> +capability.
> +.TP
> 
> I was struggling with this.  The POSIX part of RLIMIT_NOFILE is applied 
> per-process.  But the part we're talking about here, the Linux-specific 
> "unix_inflight" resource, is actually accounted per-user.  It's like 
> RLIMIT_NPROC.  The value of RLIMIT_NPROC is per-process, but the 
> resource it limits is counted in user->processes.
> 
> This subtlety of the NOFILE limit is not made clear in the text above, 
> nor in unix(7), nor in getrlimit(2).  I would interpret all these docs 
> as saying this limit is a per-process thing - I think they are misleading.

Fair point, I'll add an update to clearly state it's a per process
limit.

> IORING_MAX_FIXED_FILES is being raised to 1024, which is the same as the 
> (soft limit) value for RLIMIT_NOFILE which the kernel sets for the init 
> process.  I have an unjustifiable nervousness, that there will be some 
> `fio` command, or a test written that maxes out IORING_REGISTER_FILES.  
> When you do that, it will provoke unexpected failures e.g. in GUI apps.  
> If we can't rule that out, the next best thing is a friendly man page.

If we apply the limit to sendmsg and friends, it should be applied here
as well.

-- 
Jens Axboe


^ permalink raw reply	[flat|nested] 42+ messages in thread

* [PATCH 02/18] block: wire up block device iopoll method
  2019-02-01 15:23 [PATCHSET v11] io_uring IO interface Jens Axboe
@ 2019-02-01 15:23 ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-02-01 15:23 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api; +Cc: hch, jmoyer, avi, jannh, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Just call blk_poll on the iocb cookie, we can derive the block device
from the inode trivially.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 58a4c1217fa8..f18d076a2596 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -293,6 +293,14 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+}
+
 static void blkdev_bio_end_io(struct bio *bio)
 {
 	struct blkdev_dio *dio = bio->bi_private;
@@ -410,6 +418,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 				bio->bi_opf |= REQ_HIPRI;
 
 			qc = submit_bio(bio);
+			WRITE_ONCE(iocb->ki_cookie, qc);
 			break;
 		}
 
@@ -2076,6 +2085,7 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read_iter	= blkdev_read_iter,
 	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
 	.mmap		= generic_file_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 02/18] block: wire up block device iopoll method
  2019-01-30 21:55 [PATCHSET v10] io_uring IO interface Jens Axboe
@ 2019-01-30 21:55 ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-01-30 21:55 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api; +Cc: hch, jmoyer, avi, jannh, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Just call blk_poll on the iocb cookie, we can derive the block device
from the inode trivially.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 58a4c1217fa8..f18d076a2596 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -293,6 +293,14 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+}
+
 static void blkdev_bio_end_io(struct bio *bio)
 {
 	struct blkdev_dio *dio = bio->bi_private;
@@ -410,6 +418,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 				bio->bi_opf |= REQ_HIPRI;
 
 			qc = submit_bio(bio);
+			WRITE_ONCE(iocb->ki_cookie, qc);
 			break;
 		}
 
@@ -2076,6 +2085,7 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read_iter	= blkdev_read_iter,
 	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
 	.mmap		= generic_file_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 02/18] block: wire up block device iopoll method
  2019-01-29 19:26 [PATCHSET v9] io_uring IO interface Jens Axboe
@ 2019-01-29 19:26 ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-01-29 19:26 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-api; +Cc: hch, jmoyer, avi, jannh, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Just call blk_poll on the iocb cookie, we can derive the block device
from the inode trivially.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 58a4c1217fa8..f18d076a2596 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -293,6 +293,14 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+}
+
 static void blkdev_bio_end_io(struct bio *bio)
 {
 	struct blkdev_dio *dio = bio->bi_private;
@@ -410,6 +418,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 				bio->bi_opf |= REQ_HIPRI;
 
 			qc = submit_bio(bio);
+			WRITE_ONCE(iocb->ki_cookie, qc);
 			break;
 		}
 
@@ -2076,6 +2085,7 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read_iter	= blkdev_read_iter,
 	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
 	.mmap		= generic_file_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 02/18] block: wire up block device iopoll method
  2019-01-28 21:35 [PATCHSET v8] io_uring IO interface Jens Axboe
@ 2019-01-28 21:35 ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-01-28 21:35 UTC (permalink / raw)
  To: linux-aio, linux-block, linux-man, linux-api; +Cc: hch, jmoyer, avi, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Just call blk_poll on the iocb cookie, we can derive the block device
from the inode trivially.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 58a4c1217fa8..f18d076a2596 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -293,6 +293,14 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+}
+
 static void blkdev_bio_end_io(struct bio *bio)
 {
 	struct blkdev_dio *dio = bio->bi_private;
@@ -410,6 +418,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 				bio->bi_opf |= REQ_HIPRI;
 
 			qc = submit_bio(bio);
+			WRITE_ONCE(iocb->ki_cookie, qc);
 			break;
 		}
 
@@ -2076,6 +2085,7 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read_iter	= blkdev_read_iter,
 	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
 	.mmap		= generic_file_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

* [PATCH 02/18] block: wire up block device iopoll method
  2019-01-23 15:35 [PATCHSET v7] io_uring IO interface Jens Axboe
@ 2019-01-23 15:35 ` Jens Axboe
  0 siblings, 0 replies; 42+ messages in thread
From: Jens Axboe @ 2019-01-23 15:35 UTC (permalink / raw)
  To: linux-fsdevel, linux-aio, linux-block; +Cc: hch, jmoyer, avi, Jens Axboe

From: Christoph Hellwig <hch@lst.de>

Just call blk_poll on the iocb cookie, we can derive the block device
from the inode trivially.

Reviewed-by: Johannes Thumshirn <jthumshirn@suse.de>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---
 fs/block_dev.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/fs/block_dev.c b/fs/block_dev.c
index 58a4c1217fa8..f18d076a2596 100644
--- a/fs/block_dev.c
+++ b/fs/block_dev.c
@@ -293,6 +293,14 @@ struct blkdev_dio {
 
 static struct bio_set blkdev_dio_pool;
 
+static int blkdev_iopoll(struct kiocb *kiocb, bool wait)
+{
+	struct block_device *bdev = I_BDEV(kiocb->ki_filp->f_mapping->host);
+	struct request_queue *q = bdev_get_queue(bdev);
+
+	return blk_poll(q, READ_ONCE(kiocb->ki_cookie), wait);
+}
+
 static void blkdev_bio_end_io(struct bio *bio)
 {
 	struct blkdev_dio *dio = bio->bi_private;
@@ -410,6 +418,7 @@ __blkdev_direct_IO(struct kiocb *iocb, struct iov_iter *iter, int nr_pages)
 				bio->bi_opf |= REQ_HIPRI;
 
 			qc = submit_bio(bio);
+			WRITE_ONCE(iocb->ki_cookie, qc);
 			break;
 		}
 
@@ -2076,6 +2085,7 @@ const struct file_operations def_blk_fops = {
 	.llseek		= block_llseek,
 	.read_iter	= blkdev_read_iter,
 	.write_iter	= blkdev_write_iter,
+	.iopoll		= blkdev_iopoll,
 	.mmap		= generic_file_mmap,
 	.fsync		= blkdev_fsync,
 	.unlocked_ioctl	= block_ioctl,
-- 
2.17.1


^ permalink raw reply related	[flat|nested] 42+ messages in thread

end of thread, other threads:[~2019-02-12 21:10 UTC | newest]

Thread overview: 42+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2019-02-07 19:55 [PATCHSET v12] io_uring IO interface Jens Axboe
2019-02-07 19:55 ` [PATCH 01/18] fs: add an iopoll method to struct file_operations Jens Axboe
2019-02-07 19:55 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
2019-02-07 19:55 ` [PATCH 03/18] block: add bio_set_polled() helper Jens Axboe
2019-02-07 19:55 ` [PATCH 04/18] iomap: wire up the iopoll method Jens Axboe
2019-02-07 19:55 ` [PATCH 05/18] Add io_uring IO interface Jens Axboe
2019-02-07 20:15   ` Keith Busch
2019-02-07 20:16     ` Jens Axboe
2019-02-07 19:55 ` [PATCH 06/18] io_uring: add fsync support Jens Axboe
2019-02-07 19:55 ` [PATCH 07/18] io_uring: support for IO polling Jens Axboe
2019-02-07 19:55 ` [PATCH 08/18] fs: add fget_many() and fput_many() Jens Axboe
2019-02-07 19:55 ` [PATCH 09/18] io_uring: use fget/fput_many() for file references Jens Axboe
2019-02-07 19:55 ` [PATCH 10/18] io_uring: batch io_kiocb allocation Jens Axboe
2019-02-07 19:55 ` [PATCH 11/18] block: implement bio helper to add iter bvec pages to bio Jens Axboe
2019-02-07 19:55 ` [PATCH 12/18] io_uring: add support for pre-mapped user IO buffers Jens Axboe
2019-02-07 20:57   ` Jeff Moyer
2019-02-07 21:02     ` Jens Axboe
2019-02-07 22:38   ` Jeff Moyer
2019-02-07 22:47     ` Jens Axboe
2019-02-07 19:55 ` [PATCH 13/18] io_uring: add file set registration Jens Axboe
2019-02-08 12:17   ` Alan Jenkins
2019-02-08 12:57     ` Jens Axboe
2019-02-08 14:02       ` Alan Jenkins
2019-02-08 15:13         ` Jens Axboe
2019-02-12 12:29           ` Alan Jenkins
2019-02-12 15:17             ` Jens Axboe
2019-02-12 17:21               ` Alan Jenkins
2019-02-12 17:33                 ` Jens Axboe
2019-02-12 20:23                   ` Alan Jenkins
2019-02-12 21:10                     ` Jens Axboe
2019-02-07 19:55 ` [PATCH 14/18] io_uring: add submission polling Jens Axboe
2019-02-07 19:55 ` [PATCH 15/18] io_uring: add io_kiocb ref count Jens Axboe
2019-02-07 19:55 ` [PATCH 16/18] io_uring: add support for IORING_OP_POLL Jens Axboe
2019-02-07 22:12   ` Jeff Moyer
2019-02-07 22:18     ` Jens Axboe
2019-02-07 19:55 ` [PATCH 17/18] io_uring: allow workqueue item to handle multiple buffered requests Jens Axboe
2019-02-07 19:55 ` [PATCH 18/18] io_uring: add io_uring_event cache hit information Jens Axboe
  -- strict thread matches above, loose matches on Subject: below --
2019-02-01 15:23 [PATCHSET v11] io_uring IO interface Jens Axboe
2019-02-01 15:23 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
2019-01-30 21:55 [PATCHSET v10] io_uring IO interface Jens Axboe
2019-01-30 21:55 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
2019-01-29 19:26 [PATCHSET v9] io_uring IO interface Jens Axboe
2019-01-29 19:26 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
2019-01-28 21:35 [PATCHSET v8] io_uring IO interface Jens Axboe
2019-01-28 21:35 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe
2019-01-23 15:35 [PATCHSET v7] io_uring IO interface Jens Axboe
2019-01-23 15:35 ` [PATCH 02/18] block: wire up block device iopoll method Jens Axboe

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