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| author | Lachlan McIlroy <lachlan@redback.melbourne.sgi.com> | 2008-12-24 14:07:32 +1100 |
|---|---|---|
| committer | Lachlan McIlroy <lachlan@redback.melbourne.sgi.com> | 2008-12-24 14:07:32 +1100 |
| commit | 25051158bbed127e8672b43396c71c5eb610e5f1 (patch) | |
| tree | ee93995d39c50956334157ca723f980f5d9fa7d2 | |
| parent | ad1ad968f4e7b06c75741575ea077e25a87da49a (diff) | |
| download | linux-25051158bbed127e8672b43396c71c5eb610e5f1.tar.gz linux-25051158bbed127e8672b43396c71c5eb610e5f1.tar.xz | |
[XFS] Fix race in xfs_write() between direct and buffered I/O with DMAPI
The iolock is dropped and re-acquired around the call to XFS_SEND_NAMESP().
While the iolock is released the file can become cached. We then
'goto retry' and - if we are doing direct I/O - mapping->nrpages may now be
non zero but need_i_mutex will be zero and we will hit the WARN_ON().
Since we have dropped the I/O lock then the file size may have also changed
so what we need to do here is 'goto start' like we do for the XFS_SEND_DATA()
DMAPI event.
We also need to update the filesize before releasing the iolock so that
needs to be done before the XFS_SEND_NAMESP event. If we drop the iolock
before setting the filesize we could race with a truncate.
Reviewed-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
| -rw-r--r-- | fs/xfs/linux-2.6/xfs_lrw.c | 27 |
1 files changed, 12 insertions, 15 deletions
diff --git a/fs/xfs/linux-2.6/xfs_lrw.c b/fs/xfs/linux-2.6/xfs_lrw.c index 92ce34b3787a..7e90daa0d1d1 100644 --- a/fs/xfs/linux-2.6/xfs_lrw.c +++ b/fs/xfs/linux-2.6/xfs_lrw.c @@ -707,7 +707,6 @@ start: } } -retry: /* We can write back this queue in page reclaim */ current->backing_dev_info = mapping->backing_dev_info; @@ -763,6 +762,17 @@ retry: if (ret == -EIOCBQUEUED && !(ioflags & IO_ISAIO)) ret = wait_on_sync_kiocb(iocb); + isize = i_size_read(inode); + if (unlikely(ret < 0 && ret != -EFAULT && *offset > isize)) + *offset = isize; + + if (*offset > xip->i_size) { + xfs_ilock(xip, XFS_ILOCK_EXCL); + if (*offset > xip->i_size) + xip->i_size = *offset; + xfs_iunlock(xip, XFS_ILOCK_EXCL); + } + if (ret == -ENOSPC && DM_EVENT_ENABLED(xip, DM_EVENT_NOSPACE) && !(ioflags & IO_INVIS)) { xfs_iunlock(xip, iolock); @@ -776,20 +786,7 @@ retry: xfs_ilock(xip, iolock); if (error) goto out_unlock_internal; - pos = xip->i_size; - ret = 0; - goto retry; - } - - isize = i_size_read(inode); - if (unlikely(ret < 0 && ret != -EFAULT && *offset > isize)) - *offset = isize; - - if (*offset > xip->i_size) { - xfs_ilock(xip, XFS_ILOCK_EXCL); - if (*offset > xip->i_size) - xip->i_size = *offset; - xfs_iunlock(xip, XFS_ILOCK_EXCL); + goto start; } error = -ret; |