xfs: use buf ops magic to detect btree block type

Now that we encode block magic numbers in all the buffer ops, use that
for block type detection in the ag header repair code instead of
encoding magics directly in the repair code.
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>

fs/xfs/scrub/agheader_repair.c

@@ -342,22 +342,18 @@ xrep_agf(
 		[XREP_AGF_BNOBT] = {
 			.rmap_owner = XFS_RMAP_OWN_AG,
 			.buf_ops = &xfs_bnobt_buf_ops,
-			.magic = XFS_ABTB_CRC_MAGIC,
 		},
 		[XREP_AGF_CNTBT] = {
 			.rmap_owner = XFS_RMAP_OWN_AG,
 			.buf_ops = &xfs_cntbt_buf_ops,
-			.magic = XFS_ABTC_CRC_MAGIC,
 		},
 		[XREP_AGF_RMAPBT] = {
 			.rmap_owner = XFS_RMAP_OWN_AG,
 			.buf_ops = &xfs_rmapbt_buf_ops,
-			.magic = XFS_RMAP_CRC_MAGIC,
 		},
 		[XREP_AGF_REFCOUNTBT] = {
 			.rmap_owner = XFS_RMAP_OWN_REFC,
 			.buf_ops = &xfs_refcountbt_buf_ops,
-			.magic = XFS_REFC_CRC_MAGIC,
 		},
 		[XREP_AGF_END] = {
 			.buf_ops = NULL,
@@ -875,12 +871,10 @@ xrep_agi(
 		[XREP_AGI_INOBT] = {
 			.rmap_owner = XFS_RMAP_OWN_INOBT,
 			.buf_ops = &xfs_inobt_buf_ops,
-			.magic = XFS_IBT_CRC_MAGIC,
 		},
 		[XREP_AGI_FINOBT] = {
 			.rmap_owner = XFS_RMAP_OWN_INOBT,
 			.buf_ops = &xfs_finobt_buf_ops,
-			.magic = XFS_FIBT_CRC_MAGIC,
 		},
 		[XREP_AGI_END] = {
 			.buf_ops = NULL

fs/xfs/scrub/repair.c

@@ -743,7 +743,8 @@ xrep_findroot_block(
 
 	/* Ensure the block magic matches the btree type we're looking for. */
 	btblock = XFS_BUF_TO_BLOCK(bp);
-	if (be32_to_cpu(btblock->bb_magic) != fab->magic)
+	ASSERT(fab->buf_ops->magic[1] != 0);
+	if (btblock->bb_magic != fab->buf_ops->magic[1])
 		goto out;
 
 	/*

fs/xfs/scrub/repair.h

@@ -42,9 +42,6 @@ struct xrep_find_ag_btree {
 	/* in: buffer ops */
 	const struct xfs_buf_ops	*buf_ops;
 
-	/* in: magic number of the btree */
-	uint32_t			magic;
-
 	/* out: the highest btree block found and the tree height */
 	xfs_agblock_t			root;
 	unsigned int			height;