From: Darrick J. Wong <djwong@xxxxxxxxxx>
The logic to check that the region past the end of the superblock is all
zeroes is wrong -- we don't want to check only the bytes past the end of
the maximally sized ondisk superblock structure as currently defined in
xfs_format.h; we want to check the bytes beyond the end of the ondisk as
defined by the feature bits.
Port the superblock size logic from xfs_repair and then put it to use in
xfs_scrub.
Cc: <stable@xxxxxxxxxxxxxxx> # v4.15
Fixes: 21fb4cb1981ef7 ("xfs: scrub the secondary superblocks")
Signed-off-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
fs/xfs/scrub/agheader.c | 31 +++++++++++++++++++++++++++++--
1 file changed, 29 insertions(+), 2 deletions(-)
diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c
index 88063d67cb5fd4..9f8c312dfd3c82 100644
--- a/fs/xfs/scrub/agheader.c
+++ b/fs/xfs/scrub/agheader.c
@@ -59,6 +59,32 @@ xchk_superblock_xref(
/* scrub teardown will take care of sc->sa for us */
}
+/*
+ * Calculate the ondisk superblock size in bytes given the feature set of the
+ * mounted filesystem (aka the primary sb). This is subtlely different from
+ * the logic in xfs_repair, which computes the size of a secondary sb given the
+ * featureset listed in the secondary sb.
+ */
+STATIC size_t
+xchk_superblock_ondisk_size(
+ struct xfs_mount *mp)
+{
+ if (xfs_has_metadir(mp))
+ return offsetofend(struct xfs_dsb, sb_pad);
+ if (xfs_has_metauuid(mp))
+ return offsetofend(struct xfs_dsb, sb_meta_uuid);
+ if (xfs_has_crc(mp))
+ return offsetofend(struct xfs_dsb, sb_lsn);
+ if (xfs_sb_version_hasmorebits(&mp->m_sb))
+ return offsetofend(struct xfs_dsb, sb_bad_features2);
+ if (xfs_has_logv2(mp))
+ return offsetofend(struct xfs_dsb, sb_logsunit);
+ if (xfs_has_sector(mp))
+ return offsetofend(struct xfs_dsb, sb_logsectsize);
+ /* only support dirv2 or more recent */
+ return offsetofend(struct xfs_dsb, sb_dirblklog);
+}
+
/*
* Scrub the filesystem superblock.
*
@@ -75,6 +101,7 @@ xchk_superblock(
struct xfs_buf *bp;
struct xfs_dsb *sb;
struct xfs_perag *pag;
+ size_t sblen;
xfs_agnumber_t agno;
uint32_t v2_ok;
__be32 features_mask;
@@ -388,8 +415,8 @@ xchk_superblock(
}
/* Everything else must be zero. */
- if (memchr_inv(sb + 1, 0,
- BBTOB(bp->b_length) - sizeof(struct xfs_dsb)))
+ sblen = xchk_superblock_ondisk_size(mp);
+ if (memchr_inv((char *)sb + sblen, 0, BBTOB(bp->b_length) - sblen))
xchk_block_set_corrupt(sc, bp);
xchk_superblock_xref(sc, bp);
