[PATCH 5.10 CANDIDATE v2 6/7] xfs: update superblock counters correctly for !lazysbcount

[Amir Goldstein <amir73il@gmail.com>]

From: Dave Chinner <dchinner@redhat.com>

commit 6543990a168acf366f4b6174d7bd46ba15a8a2a6 upstream.

Keep the mount superblock counters up to date for !lazysbcount
filesystems so that when we log the superblock they do not need
updating in any way because they are already correct.

It's found by what Zorro reported:
1. mkfs.xfs -f -l lazy-count=0 -m crc=0 $dev
2. mount $dev $mnt
3. fsstress -d $mnt -p 100 -n 1000 (maybe need more or less io load)
4. umount $mnt
5. xfs_repair -n $dev
and I've seen no problem with this patch.

Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reported-by: Zorro Lang <zlang@redhat.com>
Reviewed-by: Gao Xiang <hsiangkao@redhat.com>
Signed-off-by: Gao Xiang <hsiangkao@redhat.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
---
 fs/xfs/libxfs/xfs_sb.c | 16 +++++++++++++---
 fs/xfs/xfs_trans.c     |  3 +++
 2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/fs/xfs/libxfs/xfs_sb.c b/fs/xfs/libxfs/xfs_sb.c
index 5aeafa59ed27..66e8353da2f3 100644
--- a/fs/xfs/libxfs/xfs_sb.c
+++ b/fs/xfs/libxfs/xfs_sb.c
@@ -956,9 +956,19 @@ xfs_log_sb(
 	struct xfs_mount	*mp = tp->t_mountp;
 	struct xfs_buf		*bp = xfs_trans_getsb(tp);
 
-	mp->m_sb.sb_icount = percpu_counter_sum(&mp->m_icount);
-	mp->m_sb.sb_ifree = percpu_counter_sum(&mp->m_ifree);
-	mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
+	/*
+	 * Lazy sb counters don't update the in-core superblock so do that now.
+	 * If this is at unmount, the counters will be exactly correct, but at
+	 * any other time they will only be ballpark correct because of
+	 * reservations that have been taken out percpu counters. If we have an
+	 * unclean shutdown, this will be corrected by log recovery rebuilding
+	 * the counters from the AGF block counts.
+	 */
+	if (xfs_sb_version_haslazysbcount(&mp->m_sb)) {
+		mp->m_sb.sb_icount = percpu_counter_sum(&mp->m_icount);
+		mp->m_sb.sb_ifree = percpu_counter_sum(&mp->m_ifree);
+		mp->m_sb.sb_fdblocks = percpu_counter_sum(&mp->m_fdblocks);
+	}
 
 	xfs_sb_to_disk(bp->b_addr, &mp->m_sb);
 	xfs_trans_buf_set_type(tp, bp, XFS_BLFT_SB_BUF);
diff --git a/fs/xfs/xfs_trans.c b/fs/xfs/xfs_trans.c
index 2d7deacea2cf..36166bae24a6 100644
--- a/fs/xfs/xfs_trans.c
+++ b/fs/xfs/xfs_trans.c
@@ -615,6 +615,9 @@ xfs_trans_unreserve_and_mod_sb(
 
 	/* apply remaining deltas */
 	spin_lock(&mp->m_sb_lock);
+	mp->m_sb.sb_fdblocks += tp->t_fdblocks_delta + tp->t_res_fdblocks_delta;
+	mp->m_sb.sb_icount += idelta;
+	mp->m_sb.sb_ifree += ifreedelta;
 	mp->m_sb.sb_frextents += rtxdelta;
 	mp->m_sb.sb_dblocks += tp->t_dblocks_delta;
 	mp->m_sb.sb_agcount += tp->t_agcount_delta;
-- 
2.25.1