From: Hannes Reinecke <hare@suse.de>
To: Ilya Dryomov <idryomov@gmail.com>
Cc: Sage Weil <sage@redhat.com>, Daniel Disseldorp <ddiss@suse.com>,
Jens Axboe <axboe@kernel.dk>,
ceph-devel@vger.kernel.org, linux-block@vger.kernel.org,
Hannes Reinecke <hare@suse.de>
Subject: [PATCH 11/15] rbd: drop state_mutex in __rbd_img_handle_request()
Date: Fri, 31 Jan 2020 11:37:35 +0100 [thread overview]
Message-ID: <20200131103739.136098-12-hare@suse.de> (raw)
In-Reply-To: <20200131103739.136098-1-hare@suse.de>
The use of READ_ONCE/WRITE_ONCE for the image request state allows
us to drop the state_mutex in __rbd_img_handle_request().
Signed-off-by: Hannes Reinecke <hare@suse.de>
---
drivers/block/rbd.c | 26 +++++++++-----------------
1 file changed, 9 insertions(+), 17 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 671e941d6edf..db04401c4d8b 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -349,7 +349,6 @@ struct rbd_img_request {
struct list_head object_extents; /* obj_req.ex structs */
struct mutex object_mutex;
- struct mutex state_mutex;
int pending_result;
struct work_struct work;
struct kref kref;
@@ -1674,7 +1673,6 @@ static struct rbd_img_request *rbd_img_request_create(
INIT_LIST_HEAD(&img_request->lock_item);
INIT_LIST_HEAD(&img_request->object_extents);
- mutex_init(&img_request->state_mutex);
mutex_init(&img_request->object_mutex);
kref_init(&img_request->kref);
@@ -2529,7 +2527,7 @@ static int __rbd_img_fill_request(struct rbd_img_request *img_req)
}
}
mutex_unlock(&img_req->object_mutex);
- img_req->state = RBD_IMG_START;
+ WRITE_ONCE(img_req->state, RBD_IMG_START);
return 0;
}
@@ -3652,15 +3650,15 @@ static bool rbd_img_advance(struct rbd_img_request *img_req, int *result)
int ret;
dout("%s: img %p state %d\n", __func__, img_req, img_req->state);
- switch (img_req->state) {
+ switch (READ_ONCE(img_req->state)) {
case RBD_IMG_START:
rbd_assert(!*result);
- img_req->state = RBD_IMG_EXCLUSIVE_LOCK;
+ WRITE_ONCE(img_req->state, RBD_IMG_EXCLUSIVE_LOCK);
ret = rbd_img_exclusive_lock(img_req);
if (ret < 0) {
*result = ret;
- img_req->state = RBD_IMG_DONE;
+ WRITE_ONCE(img_req->state, RBD_IMG_DONE);
return true;
}
if (ret == 0)
@@ -3668,17 +3666,17 @@ static bool rbd_img_advance(struct rbd_img_request *img_req, int *result)
/* fall through */
case RBD_IMG_EXCLUSIVE_LOCK:
if (*result) {
- img_req->state = RBD_IMG_DONE;
+ WRITE_ONCE(img_req->state, RBD_IMG_DONE);
return true;
}
rbd_assert(!need_exclusive_lock(img_req) ||
__rbd_is_lock_owner(rbd_dev));
- img_req->state = RBD_IMG_OBJECT_REQUESTS;
+ WRITE_ONCE(img_req->state, RBD_IMG_OBJECT_REQUESTS);
if (!rbd_img_object_requests(img_req)) {
*result = img_req->pending_result;
- img_req->state = RBD_IMG_DONE;
+ WRITE_ONCE(img_req->state, RBD_IMG_DONE);
return true;
}
return false;
@@ -3686,7 +3684,7 @@ static bool rbd_img_advance(struct rbd_img_request *img_req, int *result)
if (rbd_img_object_requests_pending(img_req))
return false;
*result = img_req->pending_result;
- img_req->state = RBD_IMG_DONE;
+ WRITE_ONCE(img_req->state, RBD_IMG_DONE);
/* fall through */
case RBD_IMG_DONE:
return true;
@@ -3706,16 +3704,12 @@ static bool __rbd_img_handle_request(struct rbd_img_request *img_req,
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) {
@@ -3985,10 +3979,8 @@ static void wake_lock_waiters(struct rbd_device *rbd_dev, int result)
}
list_for_each_entry(img_req, &rbd_dev->acquiring_list, lock_item) {
- mutex_lock(&img_req->state_mutex);
- rbd_assert(img_req->state == RBD_IMG_EXCLUSIVE_LOCK);
+ rbd_assert(READ_ONCE(img_req->state) == RBD_IMG_EXCLUSIVE_LOCK);
rbd_img_schedule(img_req, result);
- mutex_unlock(&img_req->state_mutex);
}
list_splice_tail_init(&rbd_dev->acquiring_list, &rbd_dev->running_list);
--
2.16.4
next prev parent reply other threads:[~2020-01-31 10:38 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-31 10:37 [PATCH 00/15] rbd: switch to blk-mq Hannes Reinecke
2020-01-31 10:37 ` [PATCH 01/15] rbd: lock object request list Hannes Reinecke
2020-02-03 16:38 ` Ilya Dryomov
2020-01-31 10:37 ` [PATCH 02/15] rbd: use READ_ONCE() when checking the mapping size Hannes Reinecke
2020-02-03 16:50 ` Ilya Dryomov
2020-02-04 7:05 ` Hannes Reinecke
2020-01-31 10:37 ` [PATCH 03/15] rbd: reorder rbd_img_advance() Hannes Reinecke
2020-01-31 10:37 ` [PATCH 04/15] rbd: reorder switch statement in rbd_advance_read() Hannes Reinecke
2020-01-31 10:37 ` [PATCH 05/15] rbd: reorder switch statement in rbd_advance_write() Hannes Reinecke
2020-01-31 10:37 ` [PATCH 06/15] rbd: add 'done' state for rbd_obj_advance_copyup() Hannes Reinecke
2020-01-31 10:37 ` [PATCH 07/15] rbd: use callback for image request completion Hannes Reinecke
2020-02-03 17:13 ` Ilya Dryomov
2020-01-31 10:37 ` [PATCH 08/15] rbd: add debugging statements for the state machine Hannes Reinecke
2020-01-31 10:37 ` [PATCH 09/15] rbd: count pending object requests in-line Hannes Reinecke
2020-02-03 17:47 ` Ilya Dryomov
2020-02-04 6:59 ` Hannes Reinecke
2020-01-31 10:37 ` [PATCH 10/15] rbd: kill 'work_result' Hannes Reinecke
2020-01-31 10:37 ` Hannes Reinecke [this message]
2020-02-03 18:01 ` [PATCH 11/15] rbd: drop state_mutex in __rbd_img_handle_request() Ilya Dryomov
2020-01-31 10:37 ` [PATCH 12/15] rbd: kill img_request kref Hannes Reinecke
2020-01-31 10:37 ` [PATCH 13/15] rbd: schedule image_request after preparation Hannes Reinecke
2020-02-03 18:40 ` Ilya Dryomov
2020-01-31 10:37 ` [PATCH 14/15] rbd: embed image request as blk_mq request payload Hannes Reinecke
2020-01-31 10:37 ` [PATCH 15/15] rbd: switch to blk-mq Hannes Reinecke
2020-02-03 8:36 ` Christoph Hellwig
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