From f25181f598cf4a8ccc40a51d8b74f8b555ecddee Mon Sep 17 00:00:00 2001 From: Lachlan McIlroy Date: Thu, 23 Apr 2009 22:18:00 -0400 Subject: [PATCH] xfs_file_last_byte() needs to acquire ilock We had some systems crash with this stack: [] ia64_leave_kernel+0x0/0x280 [] xfs_bmbt_get_startoff+0x0/0x20 [xfs] [] xfs_bmap_last_offset+0x210/0x280 [xfs] [] xfs_file_last_byte+0x70/0x1a0 [xfs] [] xfs_itruncate_start+0xc0/0x1a0 [xfs] [] xfs_inactive_free_eofblocks+0x290/0x460 [xfs] [] xfs_release+0x1b0/0x240 [xfs] [] xfs_file_release+0x70/0xa0 [xfs] [] __fput+0x1a0/0x420 [] 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 Reviewed-by: Christoph Hellwig Reviewed-by: Felix Blyakher Signed-off-by: Felix Blyakher --- fs/xfs/xfs_inode.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index e7ae08d1df48..123b20c8cbf2 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; } -- 2.20.1