diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c index ad255f8ab5c5548a332a64d0ba6ee8d3866601f1..47aaf8328c9758cfbec5e4025942bd956dcaf897 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) { @@ -307,12 +320,18 @@ 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) @@ -338,6 +357,11 @@ 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); @@ -353,14 +377,14 @@ 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); @@ -442,7 +466,7 @@ 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])) { @@ -484,7 +508,7 @@ 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; @@ -549,6 +573,8 @@ static void invalidate_dquots(struct super_block *sb, int type) struct dquot *dquot, *tmp; restart: + flush_delayed_work("a_release_work); + spin_lock(&dq_list_lock); list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) { if (dquot->dq_sb != sb) @@ -557,6 +583,12 @@ static void invalidate_dquots(struct super_block *sb, int type) 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; + } + dqgrab(dquot); spin_unlock(&dq_list_lock); /* @@ -599,7 +631,7 @@ 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; @@ -614,7 +646,7 @@ 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; @@ -630,6 +662,18 @@ int dquot_scan_active(struct super_block *sb, } 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) { @@ -653,23 +697,16 @@ 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); } @@ -762,13 +799,54 @@ static struct shrinker dqcache_shrinker = { .seeks = DEFAULT_SEEKS, }; +/* + * 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 @@ -780,7 +858,7 @@ 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 */ @@ -792,35 +870,15 @@ void dqput(struct dquot *dquot) 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, "a_release_work, 1); } EXPORT_SYMBOL(dqput); @@ -910,7 +968,7 @@ struct dquot *dqget(struct super_block *sb, struct kqid qid) * 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); @@ -1016,59 +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 @@ -1085,11 +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); } @@ -1106,13 +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 @@ -1427,7 +1433,7 @@ 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; @@ -1450,7 +1456,7 @@ 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); @@ -1558,7 +1564,7 @@ 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); @@ -1669,7 +1675,7 @@ 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; @@ -1739,7 +1745,7 @@ 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; @@ -1782,7 +1788,7 @@ 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); @@ -1824,7 +1830,7 @@ 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); @@ -1868,7 +1874,7 @@ 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; @@ -1923,7 +1929,7 @@ 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); @@ -2094,7 +2100,7 @@ int dquot_transfer(struct inode *inode, struct iattr *iattr) struct super_block *sb = inode->i_sb; int ret; - if (!dquot_active(inode)) + if (!inode_quota_active(inode)) return 0; if (iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)){