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Diffstat (limited to 'fs/quota/dquot.c')
-rw-r--r--fs/quota/dquot.c249
1 files changed, 127 insertions, 122 deletions
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 4d826c369da2..9e72bfe8bbad 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -225,13 +225,22 @@ static void put_quota_format(struct quota_format_type *fmt)
/*
* Dquot List Management:
- * The quota code uses four lists for dquot management: the inuse_list,
- * free_dquots, dqi_dirty_list, and dquot_hash[] array. A single dquot
- * structure may be on some of those lists, depending on its current state.
+ * The quota code uses five lists for dquot management: the inuse_list,
+ * releasing_dquots, free_dquots, dqi_dirty_list, and dquot_hash[] array.
+ * A single dquot structure may be on some of those lists, depending on
+ * its current state.
*
* All dquots are placed to the end of inuse_list when first created, and this
* list is used for invalidate operation, which must look at every dquot.
*
+ * When the last reference of a dquot will be dropped, the dquot will be
+ * added to releasing_dquots. We'd then queue work item which would call
+ * synchronize_srcu() and after that perform the final cleanup of all the
+ * dquots on the list. Both releasing_dquots and free_dquots use the
+ * dq_free list_head in the dquot struct. When a dquot is removed from
+ * releasing_dquots, a reference count is always subtracted, and if
+ * dq_count == 0 at that point, the dquot will be added to the free_dquots.
+ *
* Unused dquots (dq_count == 0) are added to the free_dquots list when freed,
* and this list is searched whenever we need an available dquot. Dquots are
* removed from the list as soon as they are used again, and
@@ -250,6 +259,7 @@ static void put_quota_format(struct quota_format_type *fmt)
static LIST_HEAD(inuse_list);
static LIST_HEAD(free_dquots);
+static LIST_HEAD(releasing_dquots);
static unsigned int dq_hash_bits, dq_hash_mask;
static struct hlist_head *dquot_hash;
@@ -260,6 +270,9 @@ static qsize_t inode_get_rsv_space(struct inode *inode);
static qsize_t __inode_get_rsv_space(struct inode *inode);
static int __dquot_initialize(struct inode *inode, int type);
+static void quota_release_workfn(struct work_struct *work);
+static DECLARE_DELAYED_WORK(quota_release_work, quota_release_workfn);
+
static inline unsigned int
hashfn(const struct super_block *sb, struct kqid qid)
{
@@ -305,12 +318,18 @@ static inline void put_dquot_last(struct dquot *dquot)
dqstats_inc(DQST_FREE_DQUOTS);
}
+static inline void put_releasing_dquots(struct dquot *dquot)
+{
+ list_add_tail(&dquot->dq_free, &releasing_dquots);
+}
+
static inline void remove_free_dquot(struct dquot *dquot)
{
if (list_empty(&dquot->dq_free))
return;
list_del_init(&dquot->dq_free);
- dqstats_dec(DQST_FREE_DQUOTS);
+ if (!atomic_read(&dquot->dq_count))
+ dqstats_dec(DQST_FREE_DQUOTS);
}
static inline void put_inuse(struct dquot *dquot)
@@ -336,6 +355,11 @@ static void wait_on_dquot(struct dquot *dquot)
mutex_unlock(&dquot->dq_lock);
}
+static inline int dquot_active(struct dquot *dquot)
+{
+ return test_bit(DQ_ACTIVE_B, &dquot->dq_flags);
+}
+
static inline int dquot_dirty(struct dquot *dquot)
{
return test_bit(DQ_MOD_B, &dquot->dq_flags);
@@ -351,14 +375,14 @@ int dquot_mark_dquot_dirty(struct dquot *dquot)
{
int ret = 1;
- if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
+ if (!dquot_active(dquot))
return 0;
if (sb_dqopt(dquot->dq_sb)->flags & DQUOT_NOLIST_DIRTY)
return test_and_set_bit(DQ_MOD_B, &dquot->dq_flags);
/* If quota is dirty already, we don't have to acquire dq_list_lock */
- if (test_bit(DQ_MOD_B, &dquot->dq_flags))
+ if (dquot_dirty(dquot))
return 1;
spin_lock(&dq_list_lock);
@@ -440,7 +464,7 @@ int dquot_acquire(struct dquot *dquot)
smp_mb__before_atomic();
set_bit(DQ_READ_B, &dquot->dq_flags);
/* Instantiate dquot if needed */
- if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags) && !dquot->dq_off) {
+ if (!dquot_active(dquot) && !dquot->dq_off) {
ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
/* Write the info if needed */
if (info_dirty(&dqopt->info[dquot->dq_id.type])) {
@@ -482,7 +506,7 @@ int dquot_commit(struct dquot *dquot)
goto out_lock;
/* Inactive dquot can be only if there was error during read/init
* => we have better not writing it */
- if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
+ if (dquot_active(dquot))
ret = dqopt->ops[dquot->dq_id.type]->commit_dqblk(dquot);
else
ret = -EIO;
@@ -547,6 +571,8 @@ static void invalidate_dquots(struct super_block *sb, int type)
struct dquot *dquot, *tmp;
restart:
+ flush_delayed_work(&quota_release_work);
+
spin_lock(&dq_list_lock);
list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) {
if (dquot->dq_sb != sb)
@@ -555,6 +581,12 @@ restart:
continue;
/* Wait for dquot users */
if (atomic_read(&dquot->dq_count)) {
+ /* dquot in releasing_dquots, flush and retry */
+ if (!list_empty(&dquot->dq_free)) {
+ spin_unlock(&dq_list_lock);
+ goto restart;
+ }
+
atomic_inc(&dquot->dq_count);
spin_unlock(&dq_list_lock);
/*
@@ -597,7 +629,7 @@ int dquot_scan_active(struct super_block *sb,
spin_lock(&dq_list_lock);
list_for_each_entry(dquot, &inuse_list, dq_inuse) {
- if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags))
+ if (!dquot_active(dquot))
continue;
if (dquot->dq_sb != sb)
continue;
@@ -612,7 +644,7 @@ int dquot_scan_active(struct super_block *sb,
* outstanding call and recheck the DQ_ACTIVE_B after that.
*/
wait_on_dquot(dquot);
- if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
+ if (dquot_active(dquot)) {
ret = fn(dquot, priv);
if (ret < 0)
goto out;
@@ -628,6 +660,18 @@ out:
}
EXPORT_SYMBOL(dquot_scan_active);
+static inline int dquot_write_dquot(struct dquot *dquot)
+{
+ int ret = dquot->dq_sb->dq_op->write_dquot(dquot);
+ if (ret < 0) {
+ quota_error(dquot->dq_sb, "Can't write quota structure "
+ "(error %d). Quota may get out of sync!", ret);
+ /* Clear dirty bit anyway to avoid infinite loop. */
+ clear_dquot_dirty(dquot);
+ }
+ return ret;
+}
+
/* Write all dquot structures to quota files */
int dquot_writeback_dquots(struct super_block *sb, int type)
{
@@ -651,23 +695,16 @@ int dquot_writeback_dquots(struct super_block *sb, int type)
dquot = list_first_entry(&dirty, struct dquot,
dq_dirty);
- WARN_ON(!test_bit(DQ_ACTIVE_B, &dquot->dq_flags));
+ WARN_ON(!dquot_active(dquot));
/* Now we have active dquot from which someone is
* holding reference so we can safely just increase
* use count */
dqgrab(dquot);
spin_unlock(&dq_list_lock);
- err = sb->dq_op->write_dquot(dquot);
- if (err) {
- /*
- * Clear dirty bit anyway to avoid infinite
- * loop here.
- */
- clear_dquot_dirty(dquot);
- if (!ret)
- ret = err;
- }
+ err = dquot_write_dquot(dquot);
+ if (err && !ret)
+ ret = err;
dqput(dquot);
spin_lock(&dq_list_lock);
}
@@ -761,12 +798,53 @@ static struct shrinker dqcache_shrinker = {
};
/*
+ * Safely release dquot and put reference to dquot.
+ */
+static void quota_release_workfn(struct work_struct *work)
+{
+ struct dquot *dquot;
+ struct list_head rls_head;
+
+ spin_lock(&dq_list_lock);
+ /* Exchange the list head to avoid livelock. */
+ list_replace_init(&releasing_dquots, &rls_head);
+ spin_unlock(&dq_list_lock);
+
+restart:
+ synchronize_srcu(&dquot_srcu);
+ spin_lock(&dq_list_lock);
+ while (!list_empty(&rls_head)) {
+ dquot = list_first_entry(&rls_head, struct dquot, dq_free);
+ /* Dquot got used again? */
+ if (atomic_read(&dquot->dq_count) > 1) {
+ remove_free_dquot(dquot);
+ atomic_dec(&dquot->dq_count);
+ continue;
+ }
+ if (dquot_dirty(dquot)) {
+ spin_unlock(&dq_list_lock);
+ /* Commit dquot before releasing */
+ dquot_write_dquot(dquot);
+ goto restart;
+ }
+ if (dquot_active(dquot)) {
+ spin_unlock(&dq_list_lock);
+ dquot->dq_sb->dq_op->release_dquot(dquot);
+ goto restart;
+ }
+ /* Dquot is inactive and clean, now move it to free list */
+ remove_free_dquot(dquot);
+ atomic_dec(&dquot->dq_count);
+ put_dquot_last(dquot);
+ }
+ spin_unlock(&dq_list_lock);
+}
+
+/*
* Put reference to dquot
*/
void dqput(struct dquot *dquot)
{
- int ret;
-
if (!dquot)
return;
#ifdef CONFIG_QUOTA_DEBUG
@@ -778,7 +856,7 @@ void dqput(struct dquot *dquot)
}
#endif
dqstats_inc(DQST_DROPS);
-we_slept:
+
spin_lock(&dq_list_lock);
if (atomic_read(&dquot->dq_count) > 1) {
/* We have more than one user... nothing to do */
@@ -790,35 +868,15 @@ we_slept:
spin_unlock(&dq_list_lock);
return;
}
+
/* Need to release dquot? */
- if (dquot_dirty(dquot)) {
- spin_unlock(&dq_list_lock);
- /* Commit dquot before releasing */
- ret = dquot->dq_sb->dq_op->write_dquot(dquot);
- if (ret < 0) {
- quota_error(dquot->dq_sb, "Can't write quota structure"
- " (error %d). Quota may get out of sync!",
- ret);
- /*
- * We clear dirty bit anyway, so that we avoid
- * infinite loop here
- */
- clear_dquot_dirty(dquot);
- }
- goto we_slept;
- }
- if (test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
- spin_unlock(&dq_list_lock);
- dquot->dq_sb->dq_op->release_dquot(dquot);
- goto we_slept;
- }
- atomic_dec(&dquot->dq_count);
#ifdef CONFIG_QUOTA_DEBUG
/* sanity check */
BUG_ON(!list_empty(&dquot->dq_free));
#endif
- put_dquot_last(dquot);
+ put_releasing_dquots(dquot);
spin_unlock(&dq_list_lock);
+ queue_delayed_work(system_unbound_wq, &quota_release_work, 1);
}
EXPORT_SYMBOL(dqput);
@@ -908,7 +966,7 @@ we_slept:
* already finished or it will be canceled due to dq_count > 1 test */
wait_on_dquot(dquot);
/* Read the dquot / allocate space in quota file */
- if (!test_bit(DQ_ACTIVE_B, &dquot->dq_flags)) {
+ if (!dquot_active(dquot)) {
int err;
err = sb->dq_op->acquire_dquot(dquot);
@@ -1014,59 +1072,7 @@ out:
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
@@ -1083,11 +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);
}
@@ -1104,13 +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
@@ -1425,7 +1431,7 @@ static int info_bdq_free(struct dquot *dquot, qsize_t space)
return QUOTA_NL_NOWARN;
}
-static int dquot_active(const struct inode *inode)
+static int inode_quota_active(const struct inode *inode)
{
struct super_block *sb = inode->i_sb;
@@ -1448,7 +1454,7 @@ static int __dquot_initialize(struct inode *inode, int type)
qsize_t rsv;
int ret = 0;
- if (!dquot_active(inode))
+ if (!inode_quota_active(inode))
return 0;
dquots = i_dquot(inode);
@@ -1556,7 +1562,7 @@ bool dquot_initialize_needed(struct inode *inode)
struct dquot **dquots;
int i;
- if (!dquot_active(inode))
+ if (!inode_quota_active(inode))
return false;
dquots = i_dquot(inode);
@@ -1667,7 +1673,7 @@ int __dquot_alloc_space(struct inode *inode, qsize_t number, int flags)
int reserve = flags & DQUOT_SPACE_RESERVE;
struct dquot **dquots;
- if (!dquot_active(inode)) {
+ if (!inode_quota_active(inode)) {
if (reserve) {
spin_lock(&inode->i_lock);
*inode_reserved_space(inode) += number;
@@ -1737,7 +1743,7 @@ int dquot_alloc_inode(struct inode *inode)
struct dquot_warn warn[MAXQUOTAS];
struct dquot * const *dquots;
- if (!dquot_active(inode))
+ if (!inode_quota_active(inode))
return 0;
for (cnt = 0; cnt < MAXQUOTAS; cnt++)
warn[cnt].w_type = QUOTA_NL_NOWARN;
@@ -1780,7 +1786,7 @@ int dquot_claim_space_nodirty(struct inode *inode, qsize_t number)
struct dquot **dquots;
int cnt, index;
- if (!dquot_active(inode)) {
+ if (!inode_quota_active(inode)) {
spin_lock(&inode->i_lock);
*inode_reserved_space(inode) -= number;
__inode_add_bytes(inode, number);
@@ -1822,7 +1828,7 @@ void dquot_reclaim_space_nodirty(struct inode *inode, qsize_t number)
struct dquot **dquots;
int cnt, index;
- if (!dquot_active(inode)) {
+ if (!inode_quota_active(inode)) {
spin_lock(&inode->i_lock);
*inode_reserved_space(inode) += number;
__inode_sub_bytes(inode, number);
@@ -1866,7 +1872,7 @@ void __dquot_free_space(struct inode *inode, qsize_t number, int flags)
struct dquot **dquots;
int reserve = flags & DQUOT_SPACE_RESERVE, index;
- if (!dquot_active(inode)) {
+ if (!inode_quota_active(inode)) {
if (reserve) {
spin_lock(&inode->i_lock);
*inode_reserved_space(inode) -= number;
@@ -1921,7 +1927,7 @@ void dquot_free_inode(struct inode *inode)
struct dquot * const *dquots;
int index;
- if (!dquot_active(inode))
+ if (!inode_quota_active(inode))
return;
dquots = i_dquot(inode);
@@ -2093,7 +2099,7 @@ int dquot_transfer(struct mnt_idmap *idmap, struct inode *inode,
struct super_block *sb = inode->i_sb;
int ret;
- if (!dquot_active(inode))
+ if (!inode_quota_active(inode))
return 0;
if (i_uid_needs_update(idmap, iattr, inode)) {
@@ -2359,11 +2365,10 @@ int dquot_load_quota_sb(struct super_block *sb, int type, int format_id,
struct quota_info *dqopt = sb_dqopt(sb);
int error;
+ lockdep_assert_held_write(&sb->s_umount);
+
/* Just unsuspend quotas? */
BUG_ON(flags & DQUOT_SUSPENDED);
- /* s_umount should be held in exclusive mode */
- if (WARN_ON_ONCE(down_read_trylock(&sb->s_umount)))
- up_read(&sb->s_umount);
if (!fmt)
return -ESRCH;