From: Goldwyn Rodrigues <rgoldwyn@suse.de>
To: linux-fsdevel@vger.kernel.org
Cc: jack@suse.com, hch@infradead.org, linux-block@vger.kernel.org,
linux-btrfs@vger.kernel.org, linux-ext4@vger.kernel.org,
linux-xfs@vger.kernel.org, sagi@grimberg.me, avi@scylladb.com,
axboe@kernel.dk, linux-api@vger.kernel.org, willy@infradead.org,
Goldwyn Rodrigues <rgoldwyn@suse.com>
Subject: [PATCH 1/8] nowait aio: Introduce IOCB_RW_FLAG_NOWAIT
Date: Wed, 15 Mar 2017 16:51:00 -0500 [thread overview]
Message-ID: <20170315215107.5628-2-rgoldwyn@suse.de> (raw)
In-Reply-To: <20170315215107.5628-1-rgoldwyn@suse.de>
From: Goldwyn Rodrigues <rgoldwyn@suse.com>
This flag informs kernel to bail out if an AIO request will block
for reasons such as file allocations, or a writeback triggered,
or would block while allocating requests while performing
direct I/O.
Unfortunately, aio_flags is not checked for validity. If we
add the flags to aio_flags, it would break existing applications
which have it set to anything besides zero or IOCB_FLAG_RESFD.
So, we are using aio_reserved1 and renaming it to aio_rw_flags.
IOCB_RW_FLAG_NOWAIT is translated to IOCB_NOWAIT for
iocb->ki_flags.
Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
fs/aio.c | 10 +++++++++-
include/linux/fs.h | 1 +
include/uapi/linux/aio_abi.h | 9 ++++++++-
3 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/fs/aio.c b/fs/aio.c
index f52d925..41409ac 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1541,11 +1541,16 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
ssize_t ret;
/* enforce forwards compatibility on users */
- if (unlikely(iocb->aio_reserved1 || iocb->aio_reserved2)) {
+ if (unlikely(iocb->aio_reserved2)) {
pr_debug("EINVAL: reserve field set\n");
return -EINVAL;
}
+ if (unlikely(iocb->aio_rw_flags & ~IOCB_RW_FLAG_NOWAIT)) {
+ pr_debug("EINVAL: aio_rw_flags set with incompatible flags\n");
+ return -EINVAL;
+ }
+
/* prevent overflows */
if (unlikely(
(iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
@@ -1586,6 +1591,9 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
req->common.ki_flags |= IOCB_EVENTFD;
}
+ if (iocb->aio_rw_flags & IOCB_RW_FLAG_NOWAIT)
+ req->common.ki_flags |= IOCB_NOWAIT;
+
ret = put_user(KIOCB_KEY, &user_iocb->aio_key);
if (unlikely(ret)) {
pr_debug("EFAULT: aio_key\n");
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 7251f7b..e8d9346 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -270,6 +270,7 @@ struct writeback_control;
#define IOCB_DSYNC (1 << 4)
#define IOCB_SYNC (1 << 5)
#define IOCB_WRITE (1 << 6)
+#define IOCB_NOWAIT (1 << 7)
struct kiocb {
struct file *ki_filp;
diff --git a/include/uapi/linux/aio_abi.h b/include/uapi/linux/aio_abi.h
index bb2554f..6d98cbe 100644
--- a/include/uapi/linux/aio_abi.h
+++ b/include/uapi/linux/aio_abi.h
@@ -54,6 +54,13 @@ enum {
*/
#define IOCB_FLAG_RESFD (1 << 0)
+/*
+ * Flags for aio_rw_flags member of "struct iocb".
+ * IOCB_RW_FLAG_NOWAIT - Set if the user wants the iocb to fail if it
+ * would block for operations such as disk allocation.
+ */
+#define IOCB_RW_FLAG_NOWAIT (1 << 1)
+
/* read() from /dev/aio returns these structures. */
struct io_event {
__u64 data; /* the data field from the iocb */
@@ -79,7 +86,7 @@ struct io_event {
struct iocb {
/* these are internal to the kernel/libc. */
__u64 aio_data; /* data to be returned in event's data */
- __u32 PADDED(aio_key, aio_reserved1);
+ __u32 PADDED(aio_key, aio_rw_flags);
/* the kernel sets aio_key to the req # */
/* common fields */
--
2.10.2
next prev parent reply other threads:[~2017-03-15 21:51 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-15 21:50 [PATCH 0/8 v3] No wait AIO Goldwyn Rodrigues
2017-03-15 21:51 ` Goldwyn Rodrigues [this message]
2017-03-15 21:51 ` [PATCH 2/8] nowait aio: Return if cannot get hold of i_rwsem Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 3/8] nowait aio: return if direct write will trigger writeback Goldwyn Rodrigues
2017-03-16 13:08 ` Matthew Wilcox
2017-03-16 13:46 ` Goldwyn Rodrigues
2017-03-16 13:20 ` Matthew Wilcox
[not found] ` <20170316132052.GG4033-PfSpb0PWhxZc2C7mugBRk2EX/6BAtgUQ@public.gmane.org>
2017-03-16 13:46 ` Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 4/8] nowait-aio: Introduce IOMAP_NOWAIT Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 5/8] nowait aio: return on congested block device Goldwyn Rodrigues
[not found] ` <20170315215107.5628-6-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-03-16 14:33 ` Jens Axboe
2017-03-17 2:03 ` Ming Lei
2017-03-17 12:23 ` Goldwyn Rodrigues
[not found] ` <eee4683d-9f44-434f-b97f-b0b24c7b3dab-tSWWG44O7X1aa/9Udqfwiw@public.gmane.org>
2017-03-24 11:32 ` Goldwyn Rodrigues
2017-03-24 14:39 ` Jens Axboe
2017-03-16 21:31 ` Dave Chinner
2017-03-17 12:23 ` Goldwyn Rodrigues
2017-03-20 17:33 ` Jan Kara
2017-03-15 21:51 ` [PATCH 6/8] nowait aio: ext4 Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 7/8] nowait aio: xfs Goldwyn Rodrigues
2017-03-15 21:51 ` [PATCH 8/8] nowait aio: btrfs Goldwyn Rodrigues
2017-04-03 18:52 [PATCH 0/8 v4] No wait AIO Goldwyn Rodrigues
[not found] ` <20170403185307.6243-1-rgoldwyn-l3A5Bk7waGM@public.gmane.org>
2017-04-03 18:53 ` [PATCH 1/8] nowait aio: Introduce IOCB_RW_FLAG_NOWAIT Goldwyn Rodrigues
2017-04-04 6:48 ` Christoph Hellwig
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