xfs: scrub the secondary superblocks

Ensure that the geometry presented in the backup superblocks matches
the primary superblock so that repair can recover the filesystem if
that primary gets corrupted.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

fs/xfs/Makefile

@@ -143,6 +143,7 @@ ifeq ($(CONFIG_XFS_ONLINE_SCRUB),y)
 
 xfs-y				+= $(addprefix scrub/, \
 				   trace.o \
+				   agheader.o \
 				   btree.o \
 				   common.o \
 				   scrub.o \

fs/xfs/libxfs/xfs_fs.h

@@ -484,9 +484,10 @@ struct xfs_scrub_metadata {
 
 /* Scrub subcommands. */
 #define XFS_SCRUB_TYPE_PROBE	0	/* presence test ioctl */
+#define XFS_SCRUB_TYPE_SB	1	/* superblock */
 
 /* Number of scrub subcommands. */
-#define XFS_SCRUB_TYPE_NR	1
+#define XFS_SCRUB_TYPE_NR	2
 
 /* i: Repair this metadata. */
 #define XFS_SCRUB_IFLAG_REPAIR		(1 << 0)

fs/xfs/scrub/common.h

@@ -76,6 +76,8 @@ void xfs_scrub_set_incomplete(struct xfs_scrub_context *sc);
 
 /* Setup functions */
 int xfs_scrub_setup_fs(struct xfs_scrub_context *sc, struct xfs_inode *ip);
+int xfs_scrub_setup_ag_header(struct xfs_scrub_context *sc,
+			      struct xfs_inode *ip);
 
 void xfs_scrub_ag_free(struct xfs_scrub_context *sc, struct xfs_scrub_ag *sa);
 int xfs_scrub_ag_init(struct xfs_scrub_context *sc, xfs_agnumber_t agno,

fs/xfs/scrub/scrub.c

@@ -158,6 +158,10 @@ static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
 		.setup	= xfs_scrub_setup_fs,
 		.scrub	= xfs_scrub_probe,
 	},
+	{ /* superblock */
+		.setup	= xfs_scrub_setup_ag_header,
+		.scrub	= xfs_scrub_superblock,
+	},
 };
 
 /* This isn't a stable feature, warn once per day. */

fs/xfs/scrub/scrub.h

@@ -67,5 +67,6 @@ struct xfs_scrub_context {
 
 /* Metadata scrubbers */
 int xfs_scrub_tester(struct xfs_scrub_context *sc);
+int xfs_scrub_superblock(struct xfs_scrub_context *sc);
 
 #endif	/* __XFS_SCRUB_SCRUB_H__ */