diff options
Diffstat (limited to 'drivers/md/dm-thin.c')
-rw-r--r-- | drivers/md/dm-thin.c | 77 |
1 files changed, 71 insertions, 6 deletions
diff --git a/drivers/md/dm-thin.c b/drivers/md/dm-thin.c index 53728be..13abade 100644 --- a/drivers/md/dm-thin.c +++ b/drivers/md/dm-thin.c @@ -232,6 +232,13 @@ struct thin_c { struct bio_list deferred_bio_list; struct bio_list retry_on_resume_list; struct rb_root sort_bio_list; /* sorted list of deferred bios */ + + /* + * Ensures the thin is not destroyed until the worker has finished + * iterating the active_thins list. + */ + atomic_t refcount; + struct completion can_destroy; }; /*----------------------------------------------------------------*/ @@ -1486,6 +1493,45 @@ static void process_thin_deferred_bios(struct thin_c *tc) blk_finish_plug(&plug); } +static void thin_get(struct thin_c *tc); +static void thin_put(struct thin_c *tc); + +/* + * We can't hold rcu_read_lock() around code that can block. So we + * find a thin with the rcu lock held; bump a refcount; then drop + * the lock. + */ +static struct thin_c *get_first_thin(struct pool *pool) +{ + struct thin_c *tc = NULL; + + rcu_read_lock(); + if (!list_empty(&pool->active_thins)) { + tc = list_entry_rcu(pool->active_thins.next, struct thin_c, list); + thin_get(tc); + } + rcu_read_unlock(); + + return tc; +} + +static struct thin_c *get_next_thin(struct pool *pool, struct thin_c *tc) +{ + struct thin_c *old_tc = tc; + + rcu_read_lock(); + list_for_each_entry_continue_rcu(tc, &pool->active_thins, list) { + thin_get(tc); + thin_put(old_tc); + rcu_read_unlock(); + return tc; + } + thin_put(old_tc); + rcu_read_unlock(); + + return NULL; +} + static void process_deferred_bios(struct pool *pool) { unsigned long flags; @@ -1493,10 +1539,11 @@ static void process_deferred_bios(struct pool *pool) struct bio_list bios; struct thin_c *tc; - rcu_read_lock(); - list_for_each_entry_rcu(tc, &pool->active_thins, list) + tc = get_first_thin(pool); + while (tc) { process_thin_deferred_bios(tc); - rcu_read_unlock(); + tc = get_next_thin(pool, tc); + } /* * If there are any deferred flush bios, we must commit @@ -1578,7 +1625,7 @@ static void noflush_work(struct thin_c *tc, void (*fn)(struct work_struct *)) { struct noflush_work w; - INIT_WORK(&w.worker, fn); + INIT_WORK_ONSTACK(&w.worker, fn); w.tc = tc; atomic_set(&w.complete, 0); init_waitqueue_head(&w.wait); @@ -3061,11 +3108,25 @@ static struct target_type pool_target = { /*---------------------------------------------------------------- * Thin target methods *--------------------------------------------------------------*/ +static void thin_get(struct thin_c *tc) +{ + atomic_inc(&tc->refcount); +} + +static void thin_put(struct thin_c *tc) +{ + if (atomic_dec_and_test(&tc->refcount)) + complete(&tc->can_destroy); +} + static void thin_dtr(struct dm_target *ti) { struct thin_c *tc = ti->private; unsigned long flags; + thin_put(tc); + wait_for_completion(&tc->can_destroy); + spin_lock_irqsave(&tc->pool->lock, flags); list_del_rcu(&tc->list); spin_unlock_irqrestore(&tc->pool->lock, flags); @@ -3101,6 +3162,7 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv) struct thin_c *tc; struct dm_dev *pool_dev, *origin_dev; struct mapped_device *pool_md; + unsigned long flags; mutex_lock(&dm_thin_pool_table.mutex); @@ -3191,9 +3253,12 @@ static int thin_ctr(struct dm_target *ti, unsigned argc, char **argv) mutex_unlock(&dm_thin_pool_table.mutex); - spin_lock(&tc->pool->lock); + atomic_set(&tc->refcount, 1); + init_completion(&tc->can_destroy); + + spin_lock_irqsave(&tc->pool->lock, flags); list_add_tail_rcu(&tc->list, &tc->pool->active_thins); - spin_unlock(&tc->pool->lock); + spin_unlock_irqrestore(&tc->pool->lock, flags); /* * This synchronize_rcu() call is needed here otherwise we risk a * wake_worker() call finding no bios to process (because the newly |