On 10/30/18 1:04 PM, Darrick J. Wong wrote:
> From: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
>
> In process_node_dir2, we need to distinguish between a directory with a
> single leafn block (yes, they exist) having no interior da nodes, and a
> directory with a da tree that incorrectly points to dablk 0. If we
> happened to fill out any part of the da cursor then we have a da btree
> with garbage in it; otherwise, we have a single leafn block.
>
> This was found by repair repeatedly rebuilding a directory containing a
> single leafn block.
>
> Fixes: 67a79e2cc932 ("xfs_repair: treat zero da btree pointers as corruption")
> Reported-by: Dave Chinner <david@xxxxxxxxxxxxx>
> Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
I'm inclined to apply Dave's revert for 4.19, and after review,
add this fix for 4.20 for more soak. Thoughts?
> ---
> repair/dir2.c | 17 ++++++++++++++---
> 1 file changed, 14 insertions(+), 3 deletions(-)
>
> diff --git a/repair/dir2.c b/repair/dir2.c
> index 3c010f50..8dd021a0 100644
> --- a/repair/dir2.c
> +++ b/repair/dir2.c
> @@ -1247,11 +1247,22 @@ process_node_dir2(
> return 1;
>
> /*
> - * Directories with a root marked XFS_DIR2_LEAFN_MAGIC are corrupt
> + * Skip directories with a root marked XFS_DIR2_LEAFN_MAGIC.
> + *
> + * Be careful here: If any level of the da cursor was filled out then
> + * the directory has a da btree containing an invalid before pointer to
> + * dblock 0, and we should move on to rebuilding the directory. If no
> + * levels in the da cursor got filled out, then we just have a single
> + * leafn block and we're done.
> */
> if (bno == 0) {
> - err_release_da_cursor(mp, &da_cursor, 0);
> - return 1;
> + if (da_cursor.active > 0) {
> + err_release_da_cursor(mp, &da_cursor, 0);
> + return 1;
> + } else {
> + release_da_cursor(mp, &da_cursor, 0);
> + return 0;
> + }
> } else {
> /*
> * Now pass cursor and bno into leaf-block processing routine.
>
