diff options
| -rw-r--r-- | fs/dquot.c | 52 |
1 files changed, 39 insertions, 13 deletions
@@ -118,8 +118,7 @@ * spinlock to internal buffers before writing. * * Lock ordering (including related VFS locks) is the following: - * i_mutex > dqonoff_sem > iprune_sem > journal_lock > dqptr_sem > - * > dquot->dq_lock > dqio_sem + * i_mutex > dqonoff_sem > journal_lock > dqptr_sem > dquot->dq_lock > dqio_sem * i_mutex on quota files is special (it's below dqio_sem) */ @@ -407,23 +406,49 @@ out_dqlock: /* Invalidate all dquots on the list. Note that this function is called after * quota is disabled and pointers from inodes removed so there cannot be new - * quota users. Also because we hold dqonoff_sem there can be no quota users - * for this sb+type at all. */ + * quota users. There can still be some users of quotas due to inodes being + * just deleted or pruned by prune_icache() (those are not attached to any + * list). We have to wait for such users. + */ static void invalidate_dquots(struct super_block *sb, int type) { struct dquot *dquot, *tmp; +restart: spin_lock(&dq_list_lock); list_for_each_entry_safe(dquot, tmp, &inuse_list, dq_inuse) { if (dquot->dq_sb != sb) continue; if (dquot->dq_type != type) continue; -#ifdef __DQUOT_PARANOIA - if (atomic_read(&dquot->dq_count)) - BUG(); -#endif - /* Quota now has no users and it has been written on last dqput() */ + /* Wait for dquot users */ + if (atomic_read(&dquot->dq_count)) { + DEFINE_WAIT(wait); + + atomic_inc(&dquot->dq_count); + prepare_to_wait(&dquot->dq_wait_unused, &wait, + TASK_UNINTERRUPTIBLE); + spin_unlock(&dq_list_lock); + /* Once dqput() wakes us up, we know it's time to free + * the dquot. + * IMPORTANT: we rely on the fact that there is always + * at most one process waiting for dquot to free. + * Otherwise dq_count would be > 1 and we would never + * wake up. + */ + if (atomic_read(&dquot->dq_count) > 1) + schedule(); + finish_wait(&dquot->dq_wait_unused, &wait); + dqput(dquot); + /* At this moment dquot() need not exist (it could be + * reclaimed by prune_dqcache(). Hence we must + * restart. */ + goto restart; + } + /* + * Quota now has no users and it has been written on last + * dqput() + */ remove_dquot_hash(dquot); remove_free_dquot(dquot); remove_inuse(dquot); @@ -540,6 +565,10 @@ we_slept: if (atomic_read(&dquot->dq_count) > 1) { /* We have more than one user... nothing to do */ atomic_dec(&dquot->dq_count); + /* Releasing dquot during quotaoff phase? */ + if (!sb_has_quota_enabled(dquot->dq_sb, dquot->dq_type) && + atomic_read(&dquot->dq_count) == 1) + wake_up(&dquot->dq_wait_unused); spin_unlock(&dq_list_lock); return; } @@ -581,6 +610,7 @@ static struct dquot *get_empty_dquot(struct super_block *sb, int type) INIT_LIST_HEAD(&dquot->dq_inuse); INIT_HLIST_NODE(&dquot->dq_hash); INIT_LIST_HEAD(&dquot->dq_dirty); + init_waitqueue_head(&dquot->dq_wait_unused); dquot->dq_sb = sb; dquot->dq_type = type; atomic_set(&dquot->dq_count, 1); @@ -732,13 +762,9 @@ static void drop_dquot_ref(struct super_block *sb, int type) { LIST_HEAD(tofree_head); - /* We need to be guarded against prune_icache to reach all the - * inodes - otherwise some can be on the local list of prune_icache */ - down(&iprune_sem); down_write(&sb_dqopt(sb)->dqptr_sem); remove_dquot_ref(sb, type, &tofree_head); up_write(&sb_dqopt(sb)->dqptr_sem); - up(&iprune_sem); put_dquot_list(&tofree_head); } |
