Move xen patchset to new version's subdir.

[ipfire-2.x.git] / src / patches / suse-2.6.27.31 / patches.suse / xfs-wait-for-all-IO-on-truncate-to-zero

From: Lachlan McIlroy <lachlan@sgi.com>
Subject: [XFS] Wait for all I/O on truncate to zero file size
Patch-mainline: ?
References: bnc#450658
    
It's possible to have outstanding xfs_ioend_t's queued when the file size
is zero. This can happen in the direct I/O path when a direct I/O write
fails due to ENOSPC. In this case the xfs_ioend_t will still be queued (ie
xfs_end_io_direct() does not know that the I/O failed so can't force the
xfs_ioend_t to be flushed synchronously).

When we truncate a file on unlink we don't know to wait for these
xfs_ioend_ts and we can have a use-after-free situation if the inode is
reclaimed before the xfs_ioend_t is finally processed.

As was suggested by Dave Chinner lets wait for all I/Os to complete when
truncating the file size to zero.

SGI-PV: 981668

SGI-Modid: xfs-linux-melb:xfs-kern:32216a

Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>
Signed-off-by: Christoph Hellwig <hch@infradead.org>
Acked-by: Jan Kara <jack@suse.cz>

Index: linux-2.6.27.5-2/fs/xfs/xfs_inode.c
===================================================================
--- linux-2.6.27.5-2.orig/fs/xfs/xfs_inode.c	2008-12-03 11:58:00.992733026 +1100
+++ linux-2.6.27.5-2/fs/xfs/xfs_inode.c	2008-12-03 11:59:17.542975042 +1100
@@ -1414,7 +1414,7 @@ xfs_itruncate_start(
 	mp = ip->i_mount;
 
 	/* wait for the completion of any pending DIOs */
-	if (new_size < ip->i_size)
+	if (new_size == 0 || new_size < ip->i_size)
 		vn_iowait(ip);
 
 	/*