[PATCH] xfs_repair: handling a block with bad crc, bad uuid, and bad magic number needs fixing

[bodonnel@redhat.com]

From: Bill O'Donnell <bodonnel@redhat.com>

In certain cases, if a block is so messed up that crc, uuid and magic number are all
bad, we need to not only detect in phase3 but fix it properly in phase6. In the
current code, the mechanism doesn't work in that it only pays attention to one of the
parameters.

Note: in this case, the nlink inode link count drops to 1, but re-running xfs_repair
fixes it back to 2. This is a side effect that should probably be handled in
update_inode_nlinks() with separate patch. Regardless, running xfs_repair twice
fixes the issue. Also, this patch fixes the issue with v5, but not v4 xfs.

Signed-off-by: Bill O'Donnell <bodonnel@redhat.com>
---
 repair/phase6.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/repair/phase6.c b/repair/phase6.c
index 4064a84b2450..677505d45357 100644
--- a/repair/phase6.c
+++ b/repair/phase6.c
@@ -2336,6 +2336,7 @@ longform_dir2_entry_check(
 	int			fixit = 0;
 	struct xfs_da_args	args;
 	int			error;
+	int			wantmagic;
 
 	*need_dot = 1;
 	freetab = malloc(FREETAB_SIZE(ip->i_disk_size / mp->m_dir_geo->blksize));
@@ -2364,7 +2365,6 @@ longform_dir2_entry_check(
 	     da_bno = (xfs_dablk_t)next_da_bno) {
 		const struct xfs_buf_ops *ops;
 		int			 error;
-		struct xfs_dir2_data_hdr *d;
 
 		next_da_bno = da_bno + mp->m_dir_geo->fsbcount - 1;
 		if (bmap_next_offset(ip, &next_da_bno)) {
@@ -2404,9 +2404,11 @@ longform_dir2_entry_check(
 		}
 
 		/* check v5 metadata */
-		d = bp->b_addr;
-		if (be32_to_cpu(d->magic) == XFS_DIR3_BLOCK_MAGIC ||
-		    be32_to_cpu(d->magic) == XFS_DIR3_DATA_MAGIC) {
+		if (xfs_has_crc(mp))
+			wantmagic = XFS_DIR3_BLOCK_MAGIC;
+		else
+			wantmagic = XFS_DIR2_BLOCK_MAGIC;
+		if (wantmagic == XFS_DIR3_BLOCK_MAGIC) {
 			error = check_dir3_header(mp, bp, ino);
 			if (error) {
 				fixit++;
-- 
2.48.1