[PATCH 5.15 5/6] xfs: disable reaping in fscounters scrub

[Leah Rumancik <leah.rumancik@gmail.com>]

From: "Darrick J. Wong" <djwong@kernel.org>

[ Upstream commit 2d5f38a31980d7090f5bf91021488dc61a0ba8ee ]

The fscounters scrub code doesn't work properly because it cannot
quiesce updates to the percpu counters in the filesystem, hence it
returns false corruption reports.  This has been fixed properly in
one of the online repair patchsets that are under review by replacing
the xchk_disable_reaping calls with an exclusive filesystem freeze.
Disabling background gc isn't sufficient to fix the problem.

In other words, scrub doesn't need to call xfs_inodegc_stop, which is
just as well since it wasn't correct to allow scrub to call
xfs_inodegc_start when something else could be calling xfs_inodegc_stop
(e.g. trying to freeze the filesystem).

Neuter the scrubber for now, and remove the xchk_*_reaping functions.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Leah Rumancik <leah.rumancik@gmail.com>
Acked-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/scrub/common.c     | 25 -------------------------
 fs/xfs/scrub/common.h     |  2 --
 fs/xfs/scrub/fscounters.c | 13 ++++++-------
 fs/xfs/scrub/scrub.c      |  2 --
 fs/xfs/scrub/scrub.h      |  1 -
 5 files changed, 6 insertions(+), 37 deletions(-)

diff --git a/fs/xfs/scrub/common.c b/fs/xfs/scrub/common.c
index bf1f3607d0b6..08df23edea72 100644
--- a/fs/xfs/scrub/common.c
+++ b/fs/xfs/scrub/common.c
@@ -864,28 +864,3 @@ xchk_ilock_inverted(
 	return -EDEADLOCK;
 }
 
-/* Pause background reaping of resources. */
-void
-xchk_stop_reaping(
-	struct xfs_scrub	*sc)
-{
-	sc->flags |= XCHK_REAPING_DISABLED;
-	xfs_blockgc_stop(sc->mp);
-	xfs_inodegc_stop(sc->mp);
-}
-
-/* Restart background reaping of resources. */
-void
-xchk_start_reaping(
-	struct xfs_scrub	*sc)
-{
-	/*
-	 * Readonly filesystems do not perform inactivation or speculative
-	 * preallocation, so there's no need to restart the workers.
-	 */
-	if (!xfs_is_readonly(sc->mp)) {
-		xfs_inodegc_start(sc->mp);
-		xfs_blockgc_start(sc->mp);
-	}
-	sc->flags &= ~XCHK_REAPING_DISABLED;
-}
diff --git a/fs/xfs/scrub/common.h b/fs/xfs/scrub/common.h
index 454145db10e7..2ca80102e704 100644
--- a/fs/xfs/scrub/common.h
+++ b/fs/xfs/scrub/common.h
@@ -148,7 +148,5 @@ static inline bool xchk_skip_xref(struct xfs_scrub_metadata *sm)
 
 int xchk_metadata_inode_forks(struct xfs_scrub *sc);
 int xchk_ilock_inverted(struct xfs_inode *ip, uint lock_mode);
-void xchk_stop_reaping(struct xfs_scrub *sc);
-void xchk_start_reaping(struct xfs_scrub *sc);
 
 #endif	/* __XFS_SCRUB_COMMON_H__ */
diff --git a/fs/xfs/scrub/fscounters.c b/fs/xfs/scrub/fscounters.c
index 48a6cbdf95d0..037541339d80 100644
--- a/fs/xfs/scrub/fscounters.c
+++ b/fs/xfs/scrub/fscounters.c
@@ -128,13 +128,6 @@ xchk_setup_fscounters(
 	if (error)
 		return error;
 
-	/*
-	 * Pause background reclaim while we're scrubbing to reduce the
-	 * likelihood of background perturbations to the counters throwing off
-	 * our calculations.
-	 */
-	xchk_stop_reaping(sc);
-
 	return xchk_trans_alloc(sc, 0);
 }
 
@@ -353,6 +346,12 @@ xchk_fscounters(
 	if (fdblocks > mp->m_sb.sb_dblocks)
 		xchk_set_corrupt(sc);
 
+	/*
+	 * XXX: We can't quiesce percpu counter updates, so exit early.
+	 * This can be re-enabled when we gain exclusive freeze functionality.
+	 */
+	return 0;
+
 	/*
 	 * If ifree exceeds icount by more than the minimum variance then
 	 * something's probably wrong with the counters.
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index 51e4c61916d2..e4d2a41983f7 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -171,8 +171,6 @@ xchk_teardown(
 	}
 	if (sc->sm->sm_flags & XFS_SCRUB_IFLAG_REPAIR)
 		mnt_drop_write_file(sc->file);
-	if (sc->flags & XCHK_REAPING_DISABLED)
-		xchk_start_reaping(sc);
 	if (sc->flags & XCHK_HAS_QUOTAOFFLOCK) {
 		mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock);
 		sc->flags &= ~XCHK_HAS_QUOTAOFFLOCK;
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index 80e5026bba44..e8d9fe9de26e 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -89,7 +89,6 @@ struct xfs_scrub {
 /* XCHK state flags grow up from zero, XREP state flags grown down from 2^31 */
 #define XCHK_TRY_HARDER		(1 << 0)  /* can't get resources, try again */
 #define XCHK_HAS_QUOTAOFFLOCK	(1 << 1)  /* we hold the quotaoff lock */
-#define XCHK_REAPING_DISABLED	(1 << 2)  /* background block reaping paused */
 #define XREP_ALREADY_FIXED	(1 << 31) /* checking our repair work */
 
 /* Metadata scrubbers */
-- 
2.42.0.515.g380fc7ccd1-goog