From db9143e2375c7c4a6140c0e139939584226a44dd Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <djwong@kernel.org>
Date: Wed, 1 Sep 2021 10:40:10 -0700
Subject: xfs: online checking of the free rt extent count

Teach the summary count checker to count the number of free realtime
extents and compare that to the superblock copy.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/fscounters.c | 72 +++++++++++++++++++++++++++++++++++++++++++++++
 fs/xfs/scrub/scrub.h      |  1 +
 fs/xfs/scrub/trace.h      | 19 +++++++++++++
 3 files changed, 92 insertions(+)

diff --git a/fs/xfs/scrub/fscounters.c b/fs/xfs/scrub/fscounters.c
index 48a6cbdf95d0..5761fa94964a 100644
--- a/fs/xfs/scrub/fscounters.c
+++ b/fs/xfs/scrub/fscounters.c
@@ -14,6 +14,8 @@
 #include "xfs_health.h"
 #include "xfs_btree.h"
 #include "xfs_ag.h"
+#include "xfs_rtalloc.h"
+#include "xfs_inode.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
 #include "scrub/trace.h"
@@ -267,6 +269,71 @@ retry:
 	return 0;
 }
 
+#ifdef CONFIG_XFS_RT
+static inline int
+xchk_fscount_add_frextent(
+	struct xfs_trans		*tp,
+	const struct xfs_rtalloc_rec	*rec,
+	void				*priv)
+{
+	struct xchk_fscounters		*fsc = priv;
+
+	fsc->frextents += rec->ar_extcount;
+	return 0;
+}
+
+/*
+ * Calculate what the superblock free realtime extent count should be given the
+ * realtime bitmap.
+ */
+STATIC int
+xchk_fscount_check_frextents(
+	struct xfs_scrub	*sc,
+	struct xchk_fscounters	*fsc)
+{
+	struct xfs_mount	*mp = sc->mp;
+	int			error;
+
+	if (!xfs_has_realtime(mp)) {
+		if (mp->m_sb.sb_frextents != 0)
+			xchk_set_corrupt(sc);
+		return 0;
+	}
+
+	fsc->frextents = 0;
+	xfs_ilock(sc->mp->m_rbmip, XFS_ILOCK_EXCL);
+	error = xfs_rtalloc_query_all(sc->tp, xchk_fscount_add_frextent, fsc);
+	if (error)
+		goto out_unlock;
+
+	spin_lock(&mp->m_sb_lock);
+
+	trace_xchk_fscounters_frextents_within_range(sc->mp, fsc->frextents,
+			mp->m_sb.sb_frextents);
+
+	if (fsc->frextents != mp->m_sb.sb_frextents)
+		xchk_set_corrupt(sc);
+	spin_unlock(&mp->m_sb_lock);
+
+out_unlock:
+	xfs_iunlock(sc->mp->m_rbmip, XFS_ILOCK_EXCL);
+	return error;
+}
+#else
+STATIC int
+xchk_fscount_check_frextents(
+	struct xfs_scrub	*sc,
+	struct xchk_fscounters	*fsc)
+{
+	struct xfs_mount	*mp = sc->mp;
+
+	if (mp->m_sb.sb_frextents != 0)
+		xchk_set_corrupt(sc);
+
+	return 0;
+}
+#endif /* CONFIG_XFS_RT */
+
 /*
  * Is the @counter reasonably close to the @expected value?
  *
@@ -378,5 +445,10 @@ xchk_fscounters(
 			fsc->fdblocks))
 		xchk_set_corrupt(sc);
 
+	/* Check the free extents counter for rt volumes. */
+	error = xchk_fscount_check_frextents(sc, fsc);
+	if (!xchk_process_error(sc, 0, XFS_SB_BLOCK(mp), &error))
+		return error;
+
 	return 0;
 }
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index 3de5287e98d8..dd45dbcbc05d 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -165,6 +165,7 @@ struct xchk_fscounters {
 	uint64_t		icount;
 	uint64_t		ifree;
 	uint64_t		fdblocks;
+	uint64_t		frextents;
 	unsigned long long	icount_min;
 	unsigned long long	icount_max;
 };
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index 93ece6df02e3..552758c3a8b8 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -657,6 +657,25 @@ TRACE_EVENT(xchk_fscounters_within_range,
 		  __entry->old_value)
 )
 
+TRACE_EVENT(xchk_fscounters_frextents_within_range,
+	TP_PROTO(struct xfs_mount *mp, uint64_t expected, int64_t curr_value),
+	TP_ARGS(mp, expected, curr_value),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(uint64_t, expected)
+		__field(int64_t, curr_value)
+	),
+	TP_fast_assign(
+		__entry->dev = mp->m_super->s_dev;
+		__entry->expected = expected;
+		__entry->curr_value = curr_value;
+	),
+	TP_printk("dev %d:%d expected %llu curr_value %lld",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->expected,
+		  __entry->curr_value)
+)
+
 /* repair tracepoints */
 #if IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR)
 
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