From: Milosz Tanski <milosz@adfin.com>
To: linux-kernel@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>,
linux-fsdevel@vger.kernel.org, linux-aio@kvack.org,
Mel Gorman <mgorman@suse.de>,
Volker Lendecke <Volker.Lendecke@sernet.de>,
Tejun Heo <tj@kernel.org>, Jeff Moyer <jmoyer@redhat.com>
Subject: [PATCH 4/7] O_NONBLOCK flag for readv2/preadv2
Date: Mon, 15 Sep 2014 16:21:14 -0400 [thread overview]
Message-ID: <ead00ff46b581749da6d1a6d2db9d8f8dc3aed67.1410810247.git.milosz@adfin.com> (raw)
In-Reply-To: <cover.1410810247.git.milosz@adfin.com>
Filesystems that generic_file_read_iter will not be allowed to perform
non-blocking reads. This only will read data if it's in the page cache and if
there is no page error (causing a re-read).
Signed-off-by: Milosz Tanski <milosz@adfin.com>
---
fs/read_write.c | 4 ++--
mm/filemap.c | 21 +++++++++++++++++++++
2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/fs/read_write.c b/fs/read_write.c
index 6c5030a..87a6034 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -908,7 +908,7 @@ SYSCALL_DEFINE4(readv2, unsigned long, fd, const struct iovec __user *, vec,
struct fd f = fdget_pos(fd);
ssize_t ret = -EBADF;
- if (flags & ~0)
+ if (flags & ~O_NONBLOCK)
return -EINVAL;
if (f.file) {
@@ -1006,7 +1006,7 @@ SYSCALL_DEFINE6(preadv2, unsigned long, fd, const struct iovec __user *, vec,
struct fd f;
ssize_t ret = -EBADF;
- if (flags & ~0)
+ if (flags & ~O_NONBLOCK)
return -EINVAL;
if (pos < 0)
return -EINVAL;
diff --git a/mm/filemap.c b/mm/filemap.c
index c95edbf..5b72572 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1483,7 +1483,10 @@ static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
cond_resched();
find_page:
page = find_get_page(mapping, index);
+
if (!page) {
+ if (flags & O_NONBLOCK)
+ goto would_block;
page_cache_sync_readahead(mapping,
ra, filp,
index, last_index - index);
@@ -1575,6 +1578,11 @@ page_ok:
continue;
page_not_up_to_date:
+ if (flags & O_NONBLOCK) {
+ page_cache_release(page);
+ goto would_block;
+ }
+
/* Get exclusive access to the page ... */
error = lock_page_killable(page);
if (unlikely(error))
@@ -1594,6 +1602,12 @@ page_not_up_to_date_locked:
goto page_ok;
}
+ if (flags & O_NONBLOCK) {
+ unlock_page(page);
+ page_cache_release(page);
+ goto would_block;
+ }
+
readpage:
/*
* A previous I/O error may have been due to temporary
@@ -1662,6 +1676,10 @@ no_cached_page:
goto out;
}
goto readpage;
+
+would_block:
+ error = -EAGAIN;
+ goto out;
}
out:
@@ -1697,6 +1715,9 @@ generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter, int flags)
size_t count = iov_iter_count(iter);
loff_t size;
+ if (flags & O_NONBLOCK)
+ return -EAGAIN;
+
if (!count)
goto out; /* skip atime */
size = i_size_read(inode);
--
1.7.9.5
next prev parent reply other threads:[~2014-09-15 20:21 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-15 20:20 [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) Milosz Tanski
2014-09-15 20:20 ` [PATCH 1/7] Prepare for adding a new readv/writev with user flags Milosz Tanski
2014-09-15 20:28 ` Al Viro
2014-09-15 21:15 ` Christoph Hellwig
2014-09-15 21:44 ` Milosz Tanski
2014-09-15 20:20 ` [PATCH 2/7] Define new syscalls readv2,preadv2,writev2,pwritev2 Milosz Tanski
2014-09-16 19:20 ` Jeff Moyer
2014-09-16 19:54 ` Milosz Tanski
2014-09-16 21:03 ` Christoph Hellwig
2014-09-17 15:43 ` Theodore Ts'o
2014-09-17 16:05 ` Milosz Tanski
2014-09-17 16:59 ` Theodore Ts'o
2014-09-17 17:24 ` Zach Brown
2014-09-15 20:20 ` [PATCH 3/7] Export new vector IO (with flags) to userland Milosz Tanski
2014-09-15 20:21 ` Milosz Tanski [this message]
2014-09-16 19:19 ` [PATCH 4/7] O_NONBLOCK flag for readv2/preadv2 Jeff Moyer
2014-09-16 19:44 ` Milosz Tanski
2014-09-16 19:53 ` Jeff Moyer
2014-09-15 20:21 ` [PATCH 5/7] documentation updates Christoph Hellwig
2014-09-15 20:21 ` [PATCH 6/7] move flags enforcement to vfs_preadv/vfs_pwritev Christoph Hellwig
2014-09-15 21:15 ` Christoph Hellwig
2014-09-15 21:45 ` Milosz Tanski
2014-09-15 20:22 ` [PATCH 7/7] check for O_NONBLOCK in all read_iter instances Christoph Hellwig
2014-09-16 19:27 ` Jeff Moyer
2014-09-16 19:45 ` Milosz Tanski
2014-09-16 21:42 ` Dave Chinner
2014-09-17 12:24 ` Benjamin LaHaise
2014-09-17 13:47 ` Theodore Ts'o
2014-09-17 13:56 ` Benjamin LaHaise
2014-09-17 15:33 ` Milosz Tanski
2014-09-17 15:49 ` Theodore Ts'o
2014-09-17 15:52 ` Zach Brown
2014-09-16 21:04 ` Christoph Hellwig
2014-09-16 21:24 ` Jeff Moyer
2014-09-15 20:27 ` [RFC PATCH 0/7] Non-blockling buffered fs read (page cache only) Milosz Tanski
2014-09-15 21:33 ` Andreas Dilger
2014-09-15 22:13 ` Milosz Tanski
2014-09-15 22:36 ` Elliott, Robert (Server Storage)
2014-09-16 18:24 ` Zach Brown
2014-09-19 11:21 ` Christoph Hellwig
2014-09-22 15:48 ` Jeff Moyer
2014-09-22 16:32 ` Milosz Tanski
2014-09-22 16:42 ` Christoph Hellwig
2014-09-22 17:02 ` Milosz Tanski
2014-09-22 16:25 ` Elliott, Robert (Server Storage)
2014-09-15 21:58 ` Jeff Moyer
2014-09-15 22:27 ` Milosz Tanski
2014-09-16 13:44 ` Jeff Moyer
2014-09-19 11:23 ` Christoph Hellwig
2014-09-16 19:30 ` Jeff Moyer
2014-09-16 20:34 ` Milosz Tanski
2014-09-16 20:49 ` Jeff Moyer
2014-09-17 14:49 ` [RFC 1/2] aio: async readahead Benjamin LaHaise
2014-09-17 15:26 ` [RFC 2/2] ext4: async readpage for indirect style inodes Benjamin LaHaise
2014-09-19 11:26 ` [RFC 1/2] aio: async readahead Christoph Hellwig
2014-09-19 16:01 ` Benjamin LaHaise
2014-09-17 22:20 ` [RFC v2 0/5] Non-blockling buffered fs read (page cache only) Milosz Tanski
2014-09-17 22:20 ` [RFC v2 1/5] Prepare for adding a new readv/writev with user flags Milosz Tanski
2014-09-17 22:20 ` [RFC v2 2/5] Define new syscalls readv2,preadv2,writev2,pwritev2 Milosz Tanski
2014-09-18 18:48 ` Darrick J. Wong
2014-09-19 10:52 ` Christoph Hellwig
2014-09-20 0:19 ` Darrick J. Wong
2014-09-17 22:20 ` [RFC v2 3/5] Export new vector IO (with flags) to userland Milosz Tanski
2014-09-17 22:20 ` [RFC v2 4/5] O_NONBLOCK flag for readv2/preadv2 Milosz Tanski
2014-09-19 11:27 ` Christoph Hellwig
2014-09-19 11:59 ` Milosz Tanski
2014-09-22 17:12 ` Jeff Moyer
2014-09-17 22:20 ` [RFC v2 5/5] Check for O_NONBLOCK in all read_iter instances Milosz Tanski
2014-09-19 11:26 ` Christoph Hellwig
2014-09-19 14:42 ` [RFC v2 0/5] Non-blockling buffered fs read (page cache only) Jonathan Corbet
2014-09-19 16:13 ` Volker Lendecke
2014-09-19 17:19 ` Milosz Tanski
2014-09-19 17:33 ` Milosz Tanski
2014-09-22 14:12 ` Jonathan Corbet
2014-09-22 14:24 ` Jeff Moyer
2014-09-22 14:25 ` Christoph Hellwig
2014-09-22 14:30 ` Milosz Tanski
2014-09-24 21:46 ` [RFC v3 0/4] vfs: " Milosz Tanski
2014-09-24 21:46 ` [RFC v3 1/4] vfs: Prepare for adding a new preadv/pwritev with user flags Milosz Tanski
2014-09-24 21:46 ` [RFC v3 2/4] vfs: Define new syscalls preadv2,pwritev2 Milosz Tanski
2014-09-24 21:46 ` [RFC v3 3/4] vfs: Export new vector IO syscalls (with flags) to userland Milosz Tanski
2014-09-24 21:46 ` [RFC v3 4/4] vfs: RWF_NONBLOCK flag for preadv2 Milosz Tanski
2014-09-25 4:06 ` [RFC v3 0/4] vfs: Non-blockling buffered fs read (page cache only) Michael Kerrisk
2014-09-25 11:16 ` Jan Kara
2014-09-25 15:48 ` Milosz Tanski
2014-10-08 2:53 ` Milosz Tanski
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