[PATCH v2 6/7] quota: simplify drop_dquot_ref()

[Baokun Li]

Now when dqput() drops the last reference count, it will call
synchronize_srcu(&dquot_srcu) in quota_release_workfn() to ensure that
no other user will use the dquot after the last reference count is dropped,
so we don't need to call synchronize_srcu(&dquot_srcu) in drop_dquot_ref()
and remove the corresponding logic directly to simplify the code.

Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
---
 fs/quota/dquot.c | 33 ++++++---------------------------
 1 file changed, 6 insertions(+), 27 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index e8e702ac64e5..df028fb2ce72 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1090,8 +1090,7 @@ static int add_dquot_ref(struct super_block *sb, int type)
  * Remove references to dquots from inode and add dquot to list for freeing
  * if we have the last reference to dquot
  */
-static void remove_inode_dquot_ref(struct inode *inode, int type,
-				   struct list_head *tofree_head)
+static void remove_inode_dquot_ref(struct inode *inode, int type)
 {
 	struct dquot **dquots = i_dquot(inode);
 	struct dquot *dquot = dquots[type];
@@ -1100,21 +1099,7 @@ static void remove_inode_dquot_ref(struct inode *inode, int type,
 		return;
 
 	dquots[type] = NULL;
-	if (list_empty(&dquot->dq_free)) {
-		/*
-		 * The inode still has reference to dquot so it can't be in the
-		 * free list
-		 */
-		spin_lock(&dq_list_lock);
-		list_add(&dquot->dq_free, tofree_head);
-		spin_unlock(&dq_list_lock);
-	} else {
-		/*
-		 * Dquot is already in a list to put so we won't drop the last
-		 * reference here.
-		 */
-		dqput(dquot);
-	}
+	dqput(dquot);
 }
 
 /*
@@ -1137,8 +1122,7 @@ static void put_dquot_list(struct list_head *tofree_head)
 	}
 }
 
-static void remove_dquot_ref(struct super_block *sb, int type,
-		struct list_head *tofree_head)
+static void remove_dquot_ref(struct super_block *sb, int type)
 {
 	struct inode *inode;
 #ifdef CONFIG_QUOTA_DEBUG
@@ -1159,7 +1143,7 @@ static void remove_dquot_ref(struct super_block *sb, int type,
 			if (unlikely(inode_get_rsv_space(inode) > 0))
 				reserved = 1;
 #endif
-			remove_inode_dquot_ref(inode, type, tofree_head);
+			remove_inode_dquot_ref(inode, type);
 		}
 		spin_unlock(&dq_data_lock);
 	}
@@ -1176,13 +1160,8 @@ static void remove_dquot_ref(struct super_block *sb, int type,
 /* Gather all references from inodes and drop them */
 static void drop_dquot_ref(struct super_block *sb, int type)
 {
-	LIST_HEAD(tofree_head);
-
-	if (sb->dq_op) {
-		remove_dquot_ref(sb, type, &tofree_head);
-		synchronize_srcu(&dquot_srcu);
-		put_dquot_list(&tofree_head);
-	}
+	if (sb->dq_op)
+		remove_dquot_ref(sb, type);
 }
 
 static inline
-- 
2.31.1