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rbd: quiescing lock should wait for image requests 

Syncing OSD requests doesn't really work.  A single image request may
be comprised of multiple object requests, each of which can go through
a series of OSD requests (original, copyups, etc).  On top of that, the
OSD cliest may be shared with other rbd devices.

What we want is to ensure that all in-flight image requests complete.
Introduce rbd_dev->running_list and block in RBD_LOCK_STATE_RELEASING
until that happens.  New OSD requests may be started during this time.

Note that __rbd_img_handle_request() acquires rbd_dev->lock_rwsem only
if need_exclusive_lock() returns true.  This avoids a deadlock similar
to the one outlined in the previous commit between unlock and I/O that
doesn't require lock, such as a read with object-map feature disabled.

Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
This commit is contained in:
Ilya Dryomov 2019-05-30 16:07:48 +02:00
parent a2b1da0979
commit e1fddc8fdd
1 changed files with 90 additions and 14 deletions
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104
drivers/block/rbd.c
View File

@ -331,6 +331,7 @@ struct rbd_img_request {
struct rbd_obj_request *obj_request; /* obj req initiator */
};
struct list_head lock_item;
struct list_head object_extents; /* obj_req.ex structs */
struct mutex state_mutex;
@ -410,6 +411,9 @@ struct rbd_device {
struct work_struct released_lock_work;
struct delayed_work lock_dwork;
struct work_struct unlock_work;
spinlock_t lock_lists_lock;
struct list_head running_list;
struct completion releasing_wait;
wait_queue_head_t lock_waitq;
struct workqueue_struct *task_wq;
@ -1726,6 +1730,7 @@ static struct rbd_img_request *rbd_img_request_create(
if (rbd_dev_parent_get(rbd_dev))
img_request_layered_set(img_request);
INIT_LIST_HEAD(&img_request->lock_item);
INIT_LIST_HEAD(&img_request->object_extents);
mutex_init(&img_request->state_mutex);
kref_init(&img_request->kref);
@ -1745,6 +1750,7 @@ static void rbd_img_request_destroy(struct kref *kref)
dout("%s: img %p\n", __func__, img_request);
WARN_ON(!list_empty(&img_request->lock_item));
for_each_obj_request_safe(img_request, obj_request, next_obj_request)
rbd_img_obj_request_del(img_request, obj_request);
@ -2872,6 +2878,50 @@ static void rbd_obj_handle_request(struct rbd_obj_request *obj_req, int result)
rbd_img_handle_request(obj_req->img_request, result);
}
static bool need_exclusive_lock(struct rbd_img_request *img_req)
{
struct rbd_device *rbd_dev = img_req->rbd_dev;
if (!(rbd_dev->header.features & RBD_FEATURE_EXCLUSIVE_LOCK))
return false;
if (rbd_dev->spec->snap_id != CEPH_NOSNAP)
return false;
rbd_assert(!test_bit(IMG_REQ_CHILD, &img_req->flags));
if (rbd_dev->opts->lock_on_read)
return true;
return rbd_img_is_write(img_req);
}
static void rbd_lock_add_request(struct rbd_img_request *img_req)
{
struct rbd_device *rbd_dev = img_req->rbd_dev;
lockdep_assert_held(&rbd_dev->lock_rwsem);
spin_lock(&rbd_dev->lock_lists_lock);
rbd_assert(list_empty(&img_req->lock_item));
list_add_tail(&img_req->lock_item, &rbd_dev->running_list);
spin_unlock(&rbd_dev->lock_lists_lock);
}
static void rbd_lock_del_request(struct rbd_img_request *img_req)
{
struct rbd_device *rbd_dev = img_req->rbd_dev;
bool need_wakeup;
lockdep_assert_held(&rbd_dev->lock_rwsem);
spin_lock(&rbd_dev->lock_lists_lock);
rbd_assert(!list_empty(&img_req->lock_item));
list_del_init(&img_req->lock_item);
need_wakeup = (rbd_dev->lock_state == RBD_LOCK_STATE_RELEASING &&
list_empty(&rbd_dev->running_list));
spin_unlock(&rbd_dev->lock_lists_lock);
if (need_wakeup)
complete(&rbd_dev->releasing_wait);
}
static void rbd_img_object_requests(struct rbd_img_request *img_req)
{
struct rbd_obj_request *obj_req;
@ -2927,9 +2977,19 @@ static bool __rbd_img_handle_request(struct rbd_img_request *img_req,
struct rbd_device *rbd_dev = img_req->rbd_dev;
bool done;
mutex_lock(&img_req->state_mutex);
done = rbd_img_advance(img_req, result);
mutex_unlock(&img_req->state_mutex);
if (need_exclusive_lock(img_req)) {
down_read(&rbd_dev->lock_rwsem);
mutex_lock(&img_req->state_mutex);
done = rbd_img_advance(img_req, result);
if (done)
rbd_lock_del_request(img_req);
mutex_unlock(&img_req->state_mutex);
up_read(&rbd_dev->lock_rwsem);
} else {
mutex_lock(&img_req->state_mutex);
done = rbd_img_advance(img_req, result);
mutex_unlock(&img_req->state_mutex);
}
if (done && *result) {
rbd_assert(*result < 0);
@ -3413,30 +3473,40 @@ again:
static bool rbd_quiesce_lock(struct rbd_device *rbd_dev)
{
bool need_wait;
dout("%s rbd_dev %p\n", __func__, rbd_dev);
lockdep_assert_held_exclusive(&rbd_dev->lock_rwsem);
if (rbd_dev->lock_state != RBD_LOCK_STATE_LOCKED)
return false;
rbd_dev->lock_state = RBD_LOCK_STATE_RELEASING;
downgrade_write(&rbd_dev->lock_rwsem);
/*
* Ensure that all in-flight IO is flushed.
*
* FIXME: ceph_osdc_sync() flushes the entire OSD client, which
* may be shared with other devices.
*/
ceph_osdc_sync(&rbd_dev->rbd_client->client->osdc);
rbd_dev->lock_state = RBD_LOCK_STATE_RELEASING;
rbd_assert(!completion_done(&rbd_dev->releasing_wait));
need_wait = !list_empty(&rbd_dev->running_list);
downgrade_write(&rbd_dev->lock_rwsem);
if (need_wait)
wait_for_completion(&rbd_dev->releasing_wait);
up_read(&rbd_dev->lock_rwsem);
down_write(&rbd_dev->lock_rwsem);
if (rbd_dev->lock_state != RBD_LOCK_STATE_RELEASING)
return false;
rbd_assert(list_empty(&rbd_dev->running_list));
return true;
}
static void __rbd_release_lock(struct rbd_device *rbd_dev)
{
rbd_assert(list_empty(&rbd_dev->running_list));
rbd_unlock(rbd_dev);
}
/*
* lock_rwsem must be held for write
*/
@ -3445,7 +3515,7 @@ static void rbd_release_lock(struct rbd_device *rbd_dev)
if (!rbd_quiesce_lock(rbd_dev))
return;
rbd_unlock(rbd_dev);
__rbd_release_lock(rbd_dev);
/*
* Give others a chance to grab the lock - we would re-acquire
@ -3819,7 +3889,7 @@ static void rbd_reacquire_lock(struct rbd_device *rbd_dev)
* Lock cookie cannot be updated on older OSDs, so do
* a manual release and queue an acquire.
*/
rbd_unlock(rbd_dev);
__rbd_release_lock(rbd_dev);
queue_delayed_work(rbd_dev->task_wq, &rbd_dev->lock_dwork, 0);
} else {
__rbd_lock(rbd_dev, cookie);
@ -4085,9 +4155,12 @@ static void rbd_queue_workfn(struct work_struct *work)
if (result)
goto err_img_request;
rbd_img_handle_request(img_request, 0);
if (must_be_locked)
if (must_be_locked) {
rbd_lock_add_request(img_request);
up_read(&rbd_dev->lock_rwsem);
}
rbd_img_handle_request(img_request, 0);
return;
err_img_request:
@ -4761,6 +4834,9 @@ static struct rbd_device *__rbd_dev_create(struct rbd_client *rbdc,
INIT_WORK(&rbd_dev->released_lock_work, rbd_notify_released_lock);
INIT_DELAYED_WORK(&rbd_dev->lock_dwork, rbd_acquire_lock);
INIT_WORK(&rbd_dev->unlock_work, rbd_release_lock_work);
spin_lock_init(&rbd_dev->lock_lists_lock);
INIT_LIST_HEAD(&rbd_dev->running_list);
init_completion(&rbd_dev->releasing_wait);
init_waitqueue_head(&rbd_dev->lock_waitq);
rbd_dev->dev.bus = &rbd_bus_type;
@ -5777,7 +5853,7 @@ static void rbd_dev_image_unlock(struct rbd_device *rbd_dev)
{
down_write(&rbd_dev->lock_rwsem);
if (__rbd_is_lock_owner(rbd_dev))
rbd_unlock(rbd_dev);
__rbd_release_lock(rbd_dev);
up_write(&rbd_dev->lock_rwsem);
}