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quota: simplify drop_dquot_ref()

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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: Baokun Li <libaokun1@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230630110822.3881712-6-libaokun1@huawei.com>
This commit is contained in:
Baokun Li 2023-06-30 19:08:22 +08:00 committed by Jan Kara
parent dabc8b2075
commit 7bce48f0fe
1 changed files with 9 additions and 61 deletions
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70
fs/quota/dquot.c
View file

@ -1072,59 +1072,7 @@ 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
@ -1141,11 +1089,16 @@ 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);
}
@ -1162,13 +1115,8 @@ 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