From: Greg KH <gregkh@suse.de>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: xfs@oss.sgi.com, Alex Elder <aelder@sgi.com>,
akpm@linux-foundation.org, torvalds@linux-foundation.org,
Christoph Hellwig <hch@lst.de>,
alan@lxorguk.ukuu.org.uk
Subject: [46/53] xfs: avoid direct I/O write vs buffered I/O race
Date: Tue, 22 Nov 2011 16:23:53 -0800 [thread overview]
Message-ID: <20111123002408.908319178@clark.kroah.org> (raw)
In-Reply-To: <20111123002419.GA8531@kroah.com>
3.0-stable review patch. If anyone has any objections, please let me know.
------------------
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>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
---
fs/xfs/linux-2.6/xfs_file.c | 17 ++++++++++++++---
1 file changed, 14 insertions(+), 3 deletions(-)
--- a/fs/xfs/linux-2.6/xfs_file.c
+++ b/fs/xfs/linux-2.6/xfs_file.c
@@ -669,6 +669,7 @@ 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);
@@ -760,14 +761,24 @@ 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)
@@ -812,7 +823,7 @@ 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)
_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs
next prev parent reply other threads:[~2011-11-23 0:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20111123002419.GA8531@kroah.com>
2011-11-23 0:23 ` [43/53] xfs: fix error handling for synchronous writes Greg KH
2011-11-23 0:23 ` [44/53] xfs: fix xfs_mark_inode_dirty during umount Greg KH
2011-11-23 0:23 ` [45/53] xfs: dont serialise direct IO reads on page cache Greg KH
2011-11-23 0:23 ` Greg KH [this message]
2011-11-23 0:23 ` [47/53] xfs: Return -EIO when xfs_vn_getattr() failed Greg KH
2011-11-23 0:23 ` [48/53] xfs: fix buffer flushing during unmount Greg KH
2011-11-23 0:23 ` [49/53] xfs: Fix possible memory corruption in xfs_readlink Greg KH
2011-11-23 0:23 ` [50/53] xfs: use doalloc flag in xfs_qm_dqattach_one() Greg KH
2011-11-23 0:23 ` [51/53] xfs: fix ->write_inode return values Greg KH
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20111123002408.908319178@clark.kroah.org \
--to=gregkh@suse.de \
--cc=aelder@sgi.com \
--cc=akpm@linux-foundation.org \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=hch@lst.de \
--cc=linux-kernel@vger.kernel.org \
--cc=stable@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=xfs@oss.sgi.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox