Commit 654ee4fc authored by Baokun Li's avatar Baokun Li Committed by openeuler-sync-bot
Browse files

quota: simplify drop_dquot_ref() 

maillist inclusion
category: bugfix
bugzilla: 188812,https://gitee.com/openeuler/kernel/issues/I7E0YR

Reference: https://www.spinics.net/lists/kernel/msg4844759.html



----------------------------------------

As Honza said, remove_inode_dquot_ref() currently does not release the
last dquot reference but instead adds the dquot to tofree_head list. This
is because dqput() can sleep while dropping of the last dquot reference
(writing back the dquot and calling ->release_dquot()) and that must not
happen under dq_list_lock. Now that dqput() queues the final dquot cleanup
into a workqueue, remove_inode_dquot_ref() can call dqput() unconditionally
and we can significantly simplify it.

Here we open code the simplified code of remove_inode_dquot_ref() into
remove_dquot_ref() and remove the function put_dquot_list() which is no
longer used.

Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
(cherry picked from commit a13fcef3)
parent fb08d1e9

fs/quota/dquot.c

+9 −61
Original line number Diff line number Diff line
@@ -1074,59 +1074,7 @@ static int add_dquot_ref(struct super_block *sb, int type) 
	return err;

}



/*

 * 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)

{

	struct dquot **dquots = i_dquot(inode);

	struct dquot *dquot = dquots[type];



	if (!dquot)

		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);

	}

}



/*

 * Free list of dquots

 * Dquots are removed from inodes and no new references can be got so we are

 * the only ones holding reference

 */

static void put_dquot_list(struct list_head *tofree_head)

{

	struct list_head *act_head;

	struct dquot *dquot;



	act_head = tofree_head->next;

	while (act_head != tofree_head) {

		dquot = list_entry(act_head, struct dquot, dq_free);

		act_head = act_head->next;

		/* Remove dquot from the list so we won't have problems... */

		list_del_init(&dquot->dq_free);

		dqput(dquot);

	}

}



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
@@ -1143,11 +1091,16 @@ static void remove_dquot_ref(struct super_block *sb, int type, 
		 */

		spin_lock(&dq_data_lock);

		if (!IS_NOQUOTA(inode)) {

			struct dquot **dquots = i_dquot(inode);

			struct dquot *dquot = dquots[type];



#ifdef CONFIG_QUOTA_DEBUG

			if (unlikely(inode_get_rsv_space(inode) > 0))

				reserved = 1;

#endif

			remove_inode_dquot_ref(inode, type, tofree_head);

			dquots[type] = NULL;

			if (dquot)

				dqput(dquot);

		}

		spin_unlock(&dq_data_lock);

	}
@@ -1164,13 +1117,8 @@ 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