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@xxxxxxxxx>
---
drivers/block/rbd.c | 104 ++++++++++++++++++++++++++++++++++++++------
1 file changed, 90 insertions(+), 14 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 5fcb4ebd981a..59d1fef35663 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -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 @@ static void rbd_acquire_lock(struct work_struct *work)
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);
}
--
2.19.2
