[PATCH 1/4] repair: handle directory block corruption in phase 6

[Dave Chinner <david@fromorbit.com>]

From: Dave Chinner <dchinner@redhat.com>

This should only occur in no-modify mode, but when we fail to find
the last extent in a directory btree due to corruption we need to
trash the directory if it's the first data block we find the error
on. That is because there is nothing to recover from the directory,
and if we try to scan it xfs_reapir segv's because nothing has been
read from disk.

Also catch a memory allocation failure in this code, too.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
---
 repair/phase6.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/repair/phase6.c b/repair/phase6.c
index 9b10f16..47ecad4 100644
--- a/repair/phase6.c
+++ b/repair/phase6.c
@@ -2179,7 +2179,7 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
 	freetab = malloc(FREETAB_SIZE(ip->i_d.di_size / mp->m_dirblksize));
 	if (!freetab) {
 		do_error(
-		_("malloc failed in longform_dir2_entry_check (%" PRId64 " bytes)\n"),
+_("malloc failed in longform_dir2_entry_check (%" PRId64 " bytes)\n"),
 			FREETAB_SIZE(ip->i_d.di_size / mp->m_dirblksize));
 		exit(1);
 	}
@@ -2191,6 +2191,11 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
 	}
 	num_bps = freetab->naents;
 	bplist = calloc(num_bps, sizeof(struct xfs_buf*));
+	if (!bplist)
+		do_error(
+_("calloc failed in longform_dir2_entry_check (%zu bytes)\n"),
+			num_bps * sizeof(struct xfs_buf*));
+
 	/* is this a block, leaf, or node directory? */
 	libxfs_dir2_isblock(NULL, ip, &isblock);
 	libxfs_dir2_isleaf(NULL, ip, &isleaf);
@@ -2203,8 +2208,18 @@ longform_dir2_entry_check(xfs_mount_t	*mp,
 		int			 error;
 
 		next_da_bno = da_bno + mp->m_dirblkfsbs - 1;
-		if (bmap_next_offset(NULL, ip, &next_da_bno, XFS_DATA_FORK))
+		if (bmap_next_offset(NULL, ip, &next_da_bno, XFS_DATA_FORK)) {
+			/*
+			 * if this is the first block, there isn't anything we
+			 * can recover so we just trash it.
+			 */
+			 if (da_bno == 0) {
+				fixit++;
+				goto out_fix;
+			}
 			break;
+		}
+
 		db = xfs_dir2_da_to_db(mp, da_bno);
 		if (db >= num_bps) {
 			/* more data blocks than expected */
-- 
2.0.0

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