[PATCH] xfs_repair: coordinate parallel updates to the rt bitmap

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

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

Actually take the rt lock before updating the bitmap from multiple
threads.  This fixes an infrequent corruption problem when running
generic/013 and rtinherit=1 is set on the root dir.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 repair/dinode.c |    4 ++++
 1 file changed, 4 insertions(+)

diff --git a/repair/dinode.c b/repair/dinode.c
index 57013bf149b2..07f3f83aef8c 100644
--- a/repair/dinode.c
+++ b/repair/dinode.c
@@ -184,6 +184,7 @@ process_rt_rec(
 	xfs_rfsblock_t		*tot,
 	int			check_dups)
 {
+	struct aglock		*lock = &ag_locks[(signed)NULLAGNUMBER];
 	xfs_fsblock_t		b, lastb;
 	xfs_rtblock_t		ext;
 	int			state;
@@ -245,6 +246,7 @@ _("data fork in rt ino %" PRIu64 " claims dup rt extent,"
 			continue;
 		}
 
+		pthread_mutex_lock(&lock->lock);
 		state = get_rtbmap(ext);
 		switch (state)  {
 		case XR_E_FREE:
@@ -270,6 +272,7 @@ _("data fork in rt inode %" PRIu64 " found metadata block %" PRIu64 " in rt bmap
 			do_warn(
 _("data fork in rt inode %" PRIu64 " claims used rt block %" PRIu64 "\n"),
 				ino, ext);
+			pthread_mutex_unlock(&lock->lock);
 			return 1;
 		case XR_E_FREE1:
 		default:
@@ -277,6 +280,7 @@ _("data fork in rt inode %" PRIu64 " claims used rt block %" PRIu64 "\n"),
 _("illegal state %d in rt block map %" PRIu64 "\n"),
 				state, b);
 		}
+		pthread_mutex_unlock(&lock->lock);
 	}
 
 	/*