* 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
+ * When the last reference of a dquot is dropped, the dquot is added to
+ * releasing_dquots. We'll then queue work item which will 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.
+ * dquots on the list. Each cleaned up dquot is moved to free_dquots list.
+ * Both releasing_dquots and free_dquots use the dq_free list_head in the dquot
+ * struct.
*
- * 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
- * dqstats.free_dquots gives the number of dquots on the list. When
- * dquot is invalidated it's completely released from memory.
+ * Unused and cleaned up dquots are in the free_dquots list 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 dqstats.free_dquots gives the number
+ * of dquots on the list. When dquot is invalidated it's completely released
+ * from memory.
*
* Dirty dquots are added to the dqi_dirty_list of quota_info when mark
* dirtied, and this list is searched when writing dirty dquots back to
static inline void put_releasing_dquots(struct dquot *dquot)
{
list_add_tail(&dquot->dq_free, &releasing_dquots);
+ set_bit(DQ_RELEASING_B, &dquot->dq_flags);
}
static inline void remove_free_dquot(struct dquot *dquot)
if (list_empty(&dquot->dq_free))
return;
list_del_init(&dquot->dq_free);
- if (!atomic_read(&dquot->dq_count))
+ if (!test_bit(DQ_RELEASING_B, &dquot->dq_flags))
dqstats_dec(DQST_FREE_DQUOTS);
+ else
+ clear_bit(DQ_RELEASING_B, &dquot->dq_flags);
}
static inline void put_inuse(struct dquot *dquot)
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);
/*
goto restart;
}
/*
+ * The last user already dropped its reference but dquot didn't
+ * get fully cleaned up yet. Restart the scan which flushes the
+ * work cleaning up released dquots.
+ */
+ if (test_bit(DQ_RELEASING_B, &dquot->dq_flags)) {
+ spin_unlock(&dq_list_lock);
+ goto restart;
+ }
+ /*
* Quota now has no users and it has been written on last
* dqput()
*/
dq_dirty);
WARN_ON(!dquot_active(dquot));
+ /* If the dquot is releasing we should not touch it */
+ if (test_bit(DQ_RELEASING_B, &dquot->dq_flags)) {
+ spin_unlock(&dq_list_lock);
+ flush_delayed_work("a_release_work);
+ spin_lock(&dq_list_lock);
+ continue;
+ }
/* Now we have active dquot from which someone is
* holding reference so we can safely just increase
/* Exchange the list head to avoid livelock. */
list_replace_init(&releasing_dquots, &rls_head);
spin_unlock(&dq_list_lock);
+ synchronize_srcu(&dquot_srcu);
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;
- }
+ WARN_ON_ONCE(atomic_read(&dquot->dq_count));
+ /*
+ * Note that DQ_RELEASING_B protects us from racing with
+ * invalidate_dquots() calls so we are safe to work with the
+ * dquot even after we drop dq_list_lock.
+ */
if (dquot_dirty(dquot)) {
spin_unlock(&dq_list_lock);
/* Commit dquot before releasing */
}
/* 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);
BUG_ON(!list_empty(&dquot->dq_free));
#endif
put_releasing_dquots(dquot);
+ atomic_dec(&dquot->dq_count);
spin_unlock(&dq_list_lock);
queue_delayed_work(system_unbound_wq, "a_release_work, 1);
}
dqstats_inc(DQST_LOOKUPS);
}
/* Wait for dq_lock - after this we know that either dquot_release() is
- * already finished or it will be canceled due to dq_count > 1 test */
+ * already finished or it will be canceled due to dq_count > 0 test */
wait_on_dquot(dquot);
/* Read the dquot / allocate space in quota file */
if (!dquot_active(dquot)) {
projects / platform / kernel / linux-rpi.git / blobdiff