[PATCH 10/19] xfs: repair superblocks

["Darrick J. Wong" <darrick.wong@oracle.com>]

From: Darrick J. Wong <darrick.wong@oracle.com>

If one of the backup superblocks is found to differ seriously from
superblock 0, write out a fresh copy from the in-core sb.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/agheader.c |   35 +++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/repair.h   |    1 +
 fs/xfs/scrub/scrub.c    |    1 +
 3 files changed, 37 insertions(+)


diff --git a/fs/xfs/scrub/agheader.c b/fs/xfs/scrub/agheader.c
index 8507153..d59444c 100644
--- a/fs/xfs/scrub/agheader.c
+++ b/fs/xfs/scrub/agheader.c
@@ -472,6 +472,41 @@ xfs_scrub_superblock(
 	return error;
 }
 
+/* Repair the superblock. */
+int
+xfs_repair_superblock(
+	struct xfs_scrub_context	*sc)
+{
+	struct xfs_mount		*mp = sc->mp;
+	struct xfs_buf			*bp;
+	struct xfs_dsb			*sbp;
+	xfs_agnumber_t			agno;
+	int				error;
+
+	/* Don't try to repair AG 0's sb; let xfs_repair deal with it. */
+	agno = sc->sm->sm_agno;
+	if (agno == 0)
+		return -EOPNOTSUPP;
+
+	error = xfs_trans_read_buf(mp, sc->tp, mp->m_ddev_targp,
+		  XFS_AG_DADDR(mp, agno, XFS_SB_BLOCK(mp)),
+		  XFS_FSS_TO_BB(mp, 1), 0, &bp, NULL);
+	if (error)
+		return error;
+	bp->b_ops = &xfs_sb_buf_ops;
+
+	/* Copy AG 0's superblock to this one. */
+	sbp = XFS_BUF_TO_SBP(bp);
+	memset(sbp, 0, mp->m_sb.sb_sectsize);
+	xfs_sb_to_disk(sbp, &mp->m_sb);
+	sbp->sb_bad_features2 = sbp->sb_features2;
+
+	/* Write this to disk. */
+	xfs_trans_buf_set_type(sc->tp, bp, XFS_BLFT_SB_BUF);
+	xfs_trans_log_buf(sc->tp, bp, 0, mp->m_sb.sb_sectsize - 1);
+	return error;
+}
+
 /* AGF */
 
 /* Tally freespace record lengths. */
diff --git a/fs/xfs/scrub/repair.h b/fs/xfs/scrub/repair.h
index e0d3690..fc5dcaa 100644
--- a/fs/xfs/scrub/repair.h
+++ b/fs/xfs/scrub/repair.h
@@ -70,5 +70,6 @@ xfs_extlen_t xfs_repair_calc_ag_resblks(struct xfs_scrub_context *sc);
 int xfs_repair_setup_btree_extent_collection(struct xfs_scrub_context *sc);
 
 /* Metadata repairers */
+int xfs_repair_superblock(struct xfs_scrub_context *sc);
 
 #endif	/* __XFS_SCRUB_REPAIR_H__ */
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 9c2372e..401a446 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -216,6 +216,7 @@ static const struct xfs_scrub_meta_ops meta_scrub_ops[] = {
 	{ /* superblock */
 		.setup	= xfs_scrub_setup_ag_header,
 		.scrub	= xfs_scrub_superblock,
+		.repair	= xfs_repair_superblock,
 	},
 	{ /* agf */
 		.setup	= xfs_scrub_setup_ag_header,