[PATCH 10/10] xfs_repair: add AG btree rmaps into the filesystem after syncing sb

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

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

In rmap_store_ag_btree_rec(), we try to reserve 16 blocks to handle
adding all the AG btree rmaps to the rmap record.  Unfortunately, at
that point in phase5 we haven't yet reinitialied sb_fdblocks, so
reserving blocks can fail if repair reconstructed the primary sb from a
secondary sb.  Even if the function succeeds, this still leads to
incorrect fdblocks because phase 5 resets sb_fdblocks after running the
rmap transactions.

To avoid all this, move the rmap_store_ag_btree_rec call to after the sb
has been reset.  xfs/350 was helpful in finding cases where xfs_repair
errored out while repairing the filesystem.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 repair/phase5.c |   24 +++++++++++++++---------
 1 file changed, 15 insertions(+), 9 deletions(-)


diff --git a/repair/phase5.c b/repair/phase5.c
index 2e18cc69..7f7d3d18 100644
--- a/repair/phase5.c
+++ b/repair/phase5.c
@@ -2233,7 +2233,6 @@ phase5_func(
 #endif
 	xfs_agblock_t	num_extents;
 	struct agi_stat	agi_stat = {0,};
-	int		error;
 
 	if (verbose)
 		do_log(_("        - agno = %d\n"), agno);
@@ -2426,14 +2425,6 @@ phase5_func(
 			finish_cursor(&fino_btree_curs);
 		finish_cursor(&bcnt_btree_curs);
 
-		/*
-		 * Put the per-AG btree rmap data into the rmapbt
-		 */
-		error = rmap_store_ag_btree_rec(mp, agno);
-		if (error)
-			do_error(
-_("unable to add AG %u reverse-mapping data to btree.\n"), agno);
-
 		/*
 		 * release the incore per-AG bno/bcnt trees so
 		 * the extent nodes can be recycled
@@ -2561,6 +2552,21 @@ phase5(xfs_mount_t *mp)
 	 */
 	sync_sb(mp);
 
+	/*
+	 * Put the per-AG btree rmap data into the rmapbt now that we've reset
+	 * the superblock counters.
+	 */
+	for (agno = 0; agno < mp->m_sb.sb_agcount; agno++) {
+		error = rmap_store_ag_btree_rec(mp, agno);
+		if (error)
+			do_error(
+_("unable to add AG %u reverse-mapping data to btree.\n"), agno);
+	}
+
+	/*
+	 * Put blocks that were unnecessarily reserved for btree
+	 * reconstruction back into the filesystem free space data.
+	 */
 	error = inject_lost_blocks(mp, lost_fsb);
 	if (error)
 		do_error(_("Unable to reinsert lost blocks into filesystem.\n"));