[PATCH 07/16] xfs: drop dead dquots before scheduling inode for inactivation

["Darrick J. Wong" <djwong@kernel.org>]

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

Since we now defer inode inactivation to a background workqueue, there
can be a considerable delay between the point in time when an inode
moves into NEED_INACTIVE state (and hence quotaoff cannot reach it) and
when xfs_inactive() actually finishes the inode.  To avoid delaying
quotaoff any more than necessary, drop dead dquots as soon as we know
that we're going to inactivate the inode.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
---
 fs/xfs/xfs_icache.c |    6 ++++++
 fs/xfs/xfs_qm.c     |   28 ++++++++++++++++++++++++++++
 fs/xfs/xfs_quota.h  |    2 ++
 3 files changed, 36 insertions(+)


diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
index e094c16aa8c5..17c4cd91ea15 100644
--- a/fs/xfs/xfs_icache.c
+++ b/fs/xfs/xfs_icache.c
@@ -376,6 +376,12 @@ xfs_inode_mark_reclaimable(
 			xfs_check_delalloc(ip, XFS_COW_FORK);
 			ASSERT(0);
 		}
+	} else {
+		/*
+		 * Drop dquots for disabled quota types to avoid delaying
+		 * quotaoff while we wait for inactivation to occur.
+		 */
+		xfs_qm_prepare_inactive(ip);
 	}
 
 	XFS_STATS_INC(mp, vn_reclaim);
diff --git a/fs/xfs/xfs_qm.c b/fs/xfs/xfs_qm.c
index fe341f3fd419..b193a84e47c2 100644
--- a/fs/xfs/xfs_qm.c
+++ b/fs/xfs/xfs_qm.c
@@ -408,6 +408,34 @@ xfs_qm_dqdetach(
 	}
 }
 
+/*
+ * If a quota type is turned off but we still have a dquot attached to the
+ * inode, detach it before tagging this inode for inactivation (or reclaim) to
+ * avoid delaying quotaoff for longer than is necessary.  Because the inode has
+ * no VFS state and has not yet been tagged for reclaim or inactivation, it is
+ * safe to drop the dquots locklessly because iget, quotaoff, blockgc, and
+ * reclaim will not touch the inode.
+ */
+void
+xfs_qm_prepare_inactive(
+	struct xfs_inode	*ip)
+{
+	struct xfs_mount	*mp = ip->i_mount;
+
+	if (!XFS_IS_UQUOTA_ON(mp)) {
+		xfs_qm_dqrele(ip->i_udquot);
+		ip->i_udquot = NULL;
+	}
+	if (!XFS_IS_GQUOTA_ON(mp)) {
+		xfs_qm_dqrele(ip->i_gdquot);
+		ip->i_gdquot = NULL;
+	}
+	if (!XFS_IS_PQUOTA_ON(mp)) {
+		xfs_qm_dqrele(ip->i_pdquot);
+		ip->i_pdquot = NULL;
+	}
+}
+
 struct xfs_qm_isolate {
 	struct list_head	buffers;
 	struct list_head	dispose;
diff --git a/fs/xfs/xfs_quota.h b/fs/xfs/xfs_quota.h
index d00d01302545..75d8b7bc0e25 100644
--- a/fs/xfs/xfs_quota.h
+++ b/fs/xfs/xfs_quota.h
@@ -101,6 +101,7 @@ extern struct xfs_dquot *xfs_qm_vop_chown(struct xfs_trans *,
 extern int xfs_qm_dqattach(struct xfs_inode *);
 extern int xfs_qm_dqattach_locked(struct xfs_inode *ip, bool doalloc);
 extern void xfs_qm_dqdetach(struct xfs_inode *);
+void xfs_qm_prepare_inactive(struct xfs_inode *ip);
 extern void xfs_qm_dqrele(struct xfs_dquot *);
 extern void xfs_qm_statvfs(struct xfs_inode *, struct kstatfs *);
 extern int xfs_qm_newmount(struct xfs_mount *, uint *, uint *);
@@ -162,6 +163,7 @@ xfs_trans_reserve_quota_icreate(struct xfs_trans *tp, struct xfs_dquot *udqp,
 #define xfs_qm_dqattach(ip)						(0)
 #define xfs_qm_dqattach_locked(ip, fl)					(0)
 #define xfs_qm_dqdetach(ip)
+#define xfs_qm_prepare_inactive(ip)				((void)0)
 #define xfs_qm_dqrele(d)			do { (d) = (d); } while(0)
 #define xfs_qm_statvfs(ip, s)			do { } while(0)
 #define xfs_qm_newmount(mp, a, b)					(0)