From: Ben Myers <bpm@sgi.com>
To: greg@kroah.com, stable@vger.kernel.org
Cc: Christoph Hellwig <hch@infradead.org>,
bpm@sgi.com, Alex Elder <aelder@sgi.com>,
Christoph Hellwig <hch@lst.de>,
xfs@oss.sgi.com
Subject: [PATCH 2/6] xfs: avoid direct I/O write vs buffered I/O race
Date: Wed, 30 Nov 2011 12:10:56 -0600 [thread overview]
Message-ID: <1322676660-22945-3-git-send-email-bpm@sgi.com> (raw)
In-Reply-To: <1322676660-22945-1-git-send-email-bpm@sgi.com>
From: Christoph Hellwig <hch@infradead.org>
commit c58cb165bd44de8aaee9755a144136ae743be116 upstream.
Currently a buffered reader or writer can add pages to the pagecache
while we are waiting for the iolock in xfs_file_dio_aio_write. Prevent
this by re-checking mapping->nrpages after we got the iolock, and if
nessecary upgrade the lock to exclusive mode. To simplify this a bit
only take the ilock inside of xfs_file_aio_write_checks.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Alex Elder <aelder@sgi.com>
---
fs/xfs/xfs_file.c | 17 ++++++++++++++---
1 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
index 8fd4a07..b7e75c6 100644
--- a/fs/xfs/xfs_file.c
+++ b/fs/xfs/xfs_file.c
@@ -677,6 +677,7 @@ xfs_file_aio_write_checks(
xfs_fsize_t new_size;
int error = 0;
+ xfs_rw_ilock(ip, XFS_ILOCK_EXCL);
error = generic_write_checks(file, pos, count, S_ISBLK(inode->i_mode));
if (error) {
xfs_rw_iunlock(ip, XFS_ILOCK_EXCL | *iolock);
@@ -768,14 +769,24 @@ xfs_file_dio_aio_write(
*iolock = XFS_IOLOCK_EXCL;
else
*iolock = XFS_IOLOCK_SHARED;
- xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock);
+ xfs_rw_ilock(ip, *iolock);
ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);
if (ret)
return ret;
+ /*
+ * Recheck if there are cached pages that need invalidate after we got
+ * the iolock to protect against other threads adding new pages while
+ * we were waiting for the iolock.
+ */
+ if (mapping->nrpages && *iolock == XFS_IOLOCK_SHARED) {
+ xfs_rw_iunlock(ip, *iolock);
+ *iolock = XFS_IOLOCK_EXCL;
+ xfs_rw_ilock(ip, *iolock);
+ }
+
if (mapping->nrpages) {
- WARN_ON(*iolock != XFS_IOLOCK_EXCL);
ret = -xfs_flushinval_pages(ip, (pos & PAGE_CACHE_MASK), -1,
FI_REMAPF_LOCKED);
if (ret)
@@ -820,7 +831,7 @@ xfs_file_buffered_aio_write(
size_t count = ocount;
*iolock = XFS_IOLOCK_EXCL;
- xfs_rw_ilock(ip, XFS_ILOCK_EXCL | *iolock);
+ xfs_rw_ilock(ip, *iolock);
ret = xfs_file_aio_write_checks(file, &pos, &count, iolock);
if (ret)
--
1.7.8.rc0.46.g5ae0f
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next prev parent reply other threads:[~2011-11-30 17:58 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-11-23 21:38 [PATCH 0/6] XFS update for 3.1-stable Ben Myers
2011-11-23 21:38 ` [PATCH 1/6] xfs: don't serialise direct IO reads on page cache checks Ben Myers
2011-11-23 21:38 ` [PATCH 2/6] xfs: avoid direct I/O write vs buffered I/O race Ben Myers
2011-11-23 21:38 ` [PATCH 3/6] xfs: Return -EIO when xfs_vn_getattr() failed Ben Myers
2011-11-23 21:38 ` [PATCH 4/6] xfs: fix buffer flushing during unmount Ben Myers
2011-11-23 21:38 ` [PATCH 5/6] xfs: Fix possible memory corruption in xfs_readlink Ben Myers
2011-11-23 21:38 ` [PATCH 6/6] xfs: use doalloc flag in xfs_qm_dqattach_one() Ben Myers
2011-11-28 11:00 ` [PATCH 0/6] XFS update for 3.1-stable Christoph Hellwig
2011-11-28 13:48 ` Greg KH
2011-11-28 16:54 ` Ben Myers
2011-11-28 21:40 ` Greg KH
2011-11-30 18:10 ` XFS update for 3.1-stable (resent) Ben Myers
2011-11-30 18:10 ` [PATCH 1/6] xfs: don't serialise direct IO reads on page cache checks Ben Myers
2011-11-30 18:10 ` Ben Myers [this message]
2011-11-30 18:10 ` [PATCH 3/6] xfs: Return -EIO when xfs_vn_getattr() failed Ben Myers
2011-11-30 18:10 ` [PATCH 4/6] xfs: fix buffer flushing during unmount Ben Myers
2011-11-30 18:10 ` [PATCH 5/6] xfs: Fix possible memory corruption in xfs_readlink Ben Myers
2011-11-30 18:11 ` [PATCH 6/6] xfs: use doalloc flag in xfs_qm_dqattach_one() Ben Myers
-- strict thread matches above, loose matches on Subject: below --
2011-12-01 23:27 [PATCH 0/6] XFS update for 3.1-stable (again) Ben Myers
2011-12-01 23:27 ` [PATCH 2/6] xfs: avoid direct I/O write vs buffered I/O race Ben Myers
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