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authorLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-24 14:07:32 +1100
committerLachlan McIlroy <lachlan@redback.melbourne.sgi.com>2008-12-24 14:07:32 +1100
commit25051158bbed127e8672b43396c71c5eb610e5f1 (patch)
treeee93995d39c50956334157ca723f980f5d9fa7d2 /fs/xfs
parentad1ad968f4e7b06c75741575ea077e25a87da49a (diff)
downloadop-kernel-dev-25051158bbed127e8672b43396c71c5eb610e5f1.zip
op-kernel-dev-25051158bbed127e8672b43396c71c5eb610e5f1.tar.gz
[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>
Diffstat (limited to 'fs/xfs')
-rw-r--r--fs/xfs/linux-2.6/xfs_lrw.c27
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 92ce34b..7e90daa 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;
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