[PATCH 05/11] xfs: avoid ilock games in the quota scrubber

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

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

Now that we have a new QMOPT_QUOTIP_LOCKED flag, use it to dqget in the
quota scrubber so that we can ilock the quota ip at the start of scrub
and keep it locked all the way to the end.  This enables us to remove
quite a bit of locking-related games and manage the quota ip the same
way we treat other inodes being scrubbed.  Allocate a transaction so
that we can evade deadlock issues in bmbt lookups.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
---
 fs/xfs/scrub/quota.c |   46 ++++++++++++++++++----------------------------
 fs/xfs/scrub/scrub.c |    4 ++++
 fs/xfs/scrub/scrub.h |    1 +
 3 files changed, 23 insertions(+), 28 deletions(-)


diff --git a/fs/xfs/scrub/quota.c b/fs/xfs/scrub/quota.c
index 363e318..1068a91 100644
--- a/fs/xfs/scrub/quota.c
+++ b/fs/xfs/scrub/quota.c
@@ -66,12 +66,24 @@ xfs_scrub_setup_quota(
 	struct xfs_inode		*ip)
 {
 	uint				dqtype;
+	int				error;
+
+	if (!XFS_IS_QUOTA_RUNNING(sc->mp) || !XFS_IS_QUOTA_ON(sc->mp))
+		return -ENOENT;
 
 	dqtype = xfs_scrub_quota_to_dqtype(sc);
 	if (dqtype == 0)
 		return -EINVAL;
+	sc->has_quotaofflock = true;
+	mutex_lock(&sc->mp->m_quotainfo->qi_quotaofflock);
 	if (!xfs_this_quota_on(sc->mp, dqtype))
 		return -ENOENT;
+	error = xfs_scrub_setup_fs(sc, ip);
+	if (error)
+		return error;
+	sc->ip = xfs_quota_inode(sc->mp, dqtype);
+	xfs_ilock(sc->ip, XFS_ILOCK_EXCL);
+	sc->ilock_flags = XFS_ILOCK_EXCL;
 	return 0;
 }
 
@@ -203,7 +215,6 @@ xfs_scrub_quota(
 	struct xfs_bmbt_irec		irec = { 0 };
 	struct xfs_scrub_quota_info	sqi;
 	struct xfs_mount		*mp = sc->mp;
-	struct xfs_inode		*ip;
 	struct xfs_quotainfo		*qi = mp->m_quotainfo;
 	xfs_fileoff_t			max_dqid_off;
 	xfs_fileoff_t			off = 0;
@@ -211,25 +222,12 @@ xfs_scrub_quota(
 	int				nimaps;
 	int				error = 0;
 
-	if (!XFS_IS_QUOTA_RUNNING(mp) || !XFS_IS_QUOTA_ON(mp))
-		return -ENOENT;
-
-	mutex_lock(&qi->qi_quotaofflock);
 	dqtype = xfs_scrub_quota_to_dqtype(sc);
-	if (!xfs_this_quota_on(sc->mp, dqtype)) {
-		error = -ENOENT;
-		goto out_unlock_quota;
-	}
-
-	/* Attach to the quota inode and set sc->ip so that reporting works. */
-	ip = xfs_quota_inode(sc->mp, dqtype);
-	sc->ip = ip;
 
 	/* Look for problem extents. */
-	xfs_ilock(ip, XFS_ILOCK_EXCL);
-	if (ip->i_d.di_flags & XFS_DIFLAG_REALTIME) {
+	if (sc->ip->i_d.di_flags & XFS_DIFLAG_REALTIME) {
 		xfs_scrub_ino_set_corrupt(sc, sc->ip->i_ino);
-		goto out_unlock_inode;
+		goto out;
 	}
 	max_dqid_off = ((xfs_dqid_t)-1) / qi->qi_dqperchunk;
 	while (1) {
@@ -238,11 +236,11 @@ xfs_scrub_quota(
 
 		off = irec.br_startoff + irec.br_blockcount;
 		nimaps = 1;
-		error = xfs_bmapi_read(ip, off, -1, &irec, &nimaps,
+		error = xfs_bmapi_read(sc->ip, off, -1, &irec, &nimaps,
 				XFS_BMAPI_ENTIRE);
 		if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK, off,
 				&error))
-			goto out_unlock_inode;
+			goto out;
 		if (!nimaps)
 			break;
 		if (irec.br_startblock == HOLESTARTBLOCK)
@@ -268,26 +266,18 @@ xfs_scrub_quota(
 		    irec.br_startoff + irec.br_blockcount > max_dqid_off + 1)
 			xfs_scrub_fblock_set_corrupt(sc, XFS_DATA_FORK, off);
 	}
-	xfs_iunlock(ip, XFS_ILOCK_EXCL);
 	if (sc->sm->sm_flags & XFS_SCRUB_OFLAG_CORRUPT)
 		goto out;
 
 	/* Check all the quota items. */
 	sqi.sc = sc;
 	sqi.last_id = 0;
-	error = xfs_dquot_iterate(mp, dqtype, 0, xfs_scrub_quota_item, &sqi);
+	error = xfs_dquot_iterate(mp, dqtype, XFS_QMOPT_QUOTIP_LOCKED,
+			xfs_scrub_quota_item, &sqi);
 	if (!xfs_scrub_fblock_process_error(sc, XFS_DATA_FORK,
 			sqi.last_id * qi->qi_dqperchunk, &error))
 		goto out;
 
 out:
-	/* We set sc->ip earlier, so make sure we clear it now. */
-	sc->ip = NULL;
-out_unlock_quota:
-	mutex_unlock(&qi->qi_quotaofflock);
 	return error;
-
-out_unlock_inode:
-	xfs_iunlock(ip, XFS_ILOCK_EXCL);
-	goto out;
 }
diff --git a/fs/xfs/scrub/scrub.c b/fs/xfs/scrub/scrub.c
index cb1e727..c43ee9e 100644
--- a/fs/xfs/scrub/scrub.c
+++ b/fs/xfs/scrub/scrub.c
@@ -42,6 +42,8 @@
 #include "xfs_refcount_btree.h"
 #include "xfs_rmap.h"
 #include "xfs_rmap_btree.h"
+#include "xfs_quota.h"
+#include "xfs_qm.h"
 #include "scrub/xfs_scrub.h"
 #include "scrub/scrub.h"
 #include "scrub/common.h"
@@ -166,6 +168,8 @@ xfs_scrub_teardown(
 			iput(VFS_I(sc->ip));
 		sc->ip = NULL;
 	}
+	if (sc->has_quotaofflock)
+		mutex_unlock(&sc->mp->m_quotainfo->qi_quotaofflock);
 	if (sc->buf) {
 		kmem_free(sc->buf);
 		sc->buf = NULL;
diff --git a/fs/xfs/scrub/scrub.h b/fs/xfs/scrub/scrub.h
index 0d92af8..5d79731 100644
--- a/fs/xfs/scrub/scrub.h
+++ b/fs/xfs/scrub/scrub.h
@@ -73,6 +73,7 @@ struct xfs_scrub_context {
 	void				*buf;
 	uint				ilock_flags;
 	bool				try_harder;
+	bool				has_quotaofflock;
 
 	/* State tracking for single-AG operations. */
 	struct xfs_scrub_ag		sa;