| | Date | Thu, 22 Apr 2010 12:07:52 -0700 | | From | Greg KH <> | | Subject | [021/197] xfs: fix stale inode flush avoidance |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
------------------ From: Dave Chinner <david@fromorbit.com>
commit 4b6a46882cca8349e8942e2650c33b11bc571c92 upstream
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 <david@fromorbit.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Alex Elder <aelder@sgi.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- fs/xfs/xfs_inode.c | 21 +++++++++++++++------ 1 file changed, 15 insertions(+), 6 deletions(-) --- a/fs/xfs/xfs_inode.c +++ b/fs/xfs/xfs_inode.c @@ -2878,13 +2878,9 @@ 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; } @@ -2908,6 +2904,19 @@ 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 * to disk, because the log record didn't make it to disk!
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