From 4b6a46882cca8349e8942e2650c33b11bc571c92 Mon Sep 17 00:00:00 2001 From: Dave Chinner Date: Mon, 11 Jan 2010 11:45:21 +0000 Subject: xfs: fix stale inode flush avoidance When reclaiming stale inodes, we need to guarantee that inodes are unpinned before returning with a "clean" status. If we don't we can reclaim inodes that are pinned, leading to use after free in the transaction subsystem as transactions complete. Signed-off-by: Dave Chinner Reviewed-by: Christoph Hellwig Signed-off-by: Alex Elder --- fs/xfs/xfs_inode.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) (limited to 'fs/xfs') diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c index 391d36b0e68c..ef77fd88c8e3 100644 --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -2842,13 +2842,9 @@ xfs_iflush( /* * If the inode isn't dirty, then just release the inode flush lock and - * do nothing. Treat stale inodes the same; we cannot rely on the - * backing buffer remaining stale in cache for the remaining life of - * the stale inode and so xfs_itobp() below may give us a buffer that - * no longer contains inodes below. Doing this stale check here also - * avoids forcing the log on pinned, stale inodes. + * do nothing. */ - if (xfs_inode_clean(ip) || xfs_iflags_test(ip, XFS_ISTALE)) { + if (xfs_inode_clean(ip)) { xfs_ifunlock(ip); return 0; } @@ -2871,6 +2867,19 @@ xfs_iflush( } xfs_iunpin_wait(ip); + /* + * For stale inodes we cannot rely on the backing buffer remaining + * stale in cache for the remaining life of the stale inode and so + * xfs_itobp() below may give us a buffer that no longer contains + * inodes below. We have to check this after ensuring the inode is + * unpinned so that it is safe to reclaim the stale inode after the + * flush call. + */ + if (xfs_iflags_test(ip, XFS_ISTALE)) { + xfs_ifunlock(ip); + return 0; + } + /* * This may have been unpinned because the filesystem is shutting * down forcibly. If that's the case we must not write this inode -- cgit v1.2.3-59-g8ed1b