Gitweb: http://git.kernel.org/linus/def6b3ba56b637d58126ef67fc19bab57945fcc4
Commit: def6b3ba56b637d58126ef67fc19bab57945fcc4
Parent: dc2a5536d633dd2318f82f3d5ad3c9e43cfc21d7
Author: Lachlan McIlroy <lmcilroy@redhat.com>
AuthorDate: Thu Apr 23 22:18:00 2009 -0400
Committer: Felix Blyakher <felixb@sgi.com>
CommitDate: Thu Apr 30 00:25:25 2009 -0500
xfs_file_last_byte() needs to acquire ilock
We had some systems crash with this stack:
[<a00000010000cb20>] ia64_leave_kernel+0x0/0x280
[<a00000021291ca00>] xfs_bmbt_get_startoff+0x0/0x20 [xfs]
[<a0000002129080b0>] xfs_bmap_last_offset+0x210/0x280 [xfs]
[<a00000021295b010>] xfs_file_last_byte+0x70/0x1a0 [xfs]
[<a00000021295b200>] xfs_itruncate_start+0xc0/0x1a0 [xfs]
[<a0000002129935f0>] xfs_inactive_free_eofblocks+0x290/0x460 [xfs]
[<a000000212998fb0>] xfs_release+0x1b0/0x240 [xfs]
[<a0000002129ad930>] xfs_file_release+0x70/0xa0 [xfs]
[<a000000100162ea0>] __fput+0x1a0/0x420
[<a000000100163160>] fput+0x40/0x60
The problem here is that xfs_file_last_byte() does not acquire the
inode lock and can therefore race with another thread that is modifying
the extext list. While xfs_bmap_last_offset() is trying to lookup
what was the last extent some extents were merged and the extent list
shrunk so the index we lookup is now beyond the end of the extent list
and potentially in a freed buffer.
Signed-off-by: Lachlan McIlroy <lmcilroy@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Felix Blyakher <felixb@sgi.com>
Signed-off-by: Felix Blyakher <felixb@sgi.com>
---
fs/xfs/xfs_inode.c | 2 ++
1 files changed, 2 insertions(+), 0 deletions(-)
diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
index e7ae08d..123b20c 100644
--- a/fs/xfs/xfs_inode.c
+++ b/fs/xfs/xfs_inode.c
@@ -1258,8 +1258,10 @@ xfs_file_last_byte(
* necessary.
*/
if (ip->i_df.if_flags & XFS_IFEXTENTS) {
+ xfs_ilock(ip, XFS_ILOCK_SHARED);
error = xfs_bmap_last_offset(NULL, ip, &last_block,
XFS_DATA_FORK);
+ xfs_iunlock(ip, XFS_ILOCK_SHARED);
if (error) {
last_block = 0;
}
--
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