@@ -1601,10 +1601,8 @@ static bool rbd_dev_parent_get(struct rbd_device *rbd_dev)
if (!rbd_dev->parent_spec)
return false;
- down_read(&rbd_dev->header_rwsem);
if (rbd_dev->parent_overlap)
counter = atomic_inc_return_safe(&rbd_dev->parent_ref);
- up_read(&rbd_dev->header_rwsem);
if (counter < 0)
rbd_warn(rbd_dev, "parent reference overflow");
@@ -1619,8 +1617,7 @@ static bool rbd_dev_parent_get(struct rbd_device *rbd_dev)
*/
static struct rbd_img_request *rbd_img_request_create(
struct rbd_device *rbd_dev,
- enum obj_operation_type op_type,
- struct ceph_snap_context *snapc)
+ enum obj_operation_type op_type)
{
struct rbd_img_request *img_request;
@@ -1630,13 +1627,6 @@ static struct rbd_img_request *rbd_img_request_create(
img_request->rbd_dev = rbd_dev;
img_request->op_type = op_type;
- if (!rbd_img_is_write(img_request))
- img_request->snap_id = rbd_dev->spec->snap_id;
- else
- img_request->snapc = snapc;
-
- 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);
@@ -1645,6 +1635,21 @@ static struct rbd_img_request *rbd_img_request_create(
return img_request;
}
+static void rbd_img_capture_header(struct rbd_img_request *img_req)
+{
+ struct rbd_device *rbd_dev = img_req->rbd_dev;
+
+ lockdep_assert_held(&rbd_dev->header_rwsem);
+
+ if (rbd_img_is_write(img_req))
+ img_req->snapc = ceph_get_snap_context(rbd_dev->header.snapc);
+ else
+ img_req->snap_id = rbd_dev->spec->snap_id;
+
+ if (rbd_dev_parent_get(rbd_dev))
+ img_request_layered_set(img_req);
+}
+
static void rbd_img_request_destroy(struct rbd_img_request *img_request)
{
struct rbd_obj_request *obj_request;
@@ -2825,17 +2830,21 @@ static int rbd_obj_read_object(struct rbd_obj_request *obj_req)
static int rbd_obj_read_from_parent(struct rbd_obj_request *obj_req)
{
struct rbd_img_request *img_req = obj_req->img_request;
+ struct rbd_device *parent = img_req->rbd_dev->parent;
struct rbd_img_request *child_img_req;
int ret;
- child_img_req = rbd_img_request_create(img_req->rbd_dev->parent,
- OBJ_OP_READ, NULL);
+ child_img_req = rbd_img_request_create(parent, OBJ_OP_READ);
if (!child_img_req)
return -ENOMEM;
__set_bit(IMG_REQ_CHILD, &child_img_req->flags);
child_img_req->obj_request = obj_req;
+ down_read(&parent->header_rwsem);
+ rbd_img_capture_header(child_img_req);
+ up_read(&parent->header_rwsem);
+
dout("%s child_img_req %p for obj_req %p\n", __func__, child_img_req,
obj_req);
@@ -4686,7 +4695,6 @@ static void rbd_queue_workfn(struct work_struct *work)
struct request *rq = blk_mq_rq_from_pdu(work);
struct rbd_device *rbd_dev = rq->q->queuedata;
struct rbd_img_request *img_request;
- struct ceph_snap_context *snapc = NULL;
u64 offset = (u64)blk_rq_pos(rq) << SECTOR_SHIFT;
u64 length = blk_rq_bytes(rq);
enum obj_operation_type op_type;
@@ -4739,28 +4747,24 @@ static void rbd_queue_workfn(struct work_struct *work)
blk_mq_start_request(rq);
+ img_request = rbd_img_request_create(rbd_dev, op_type);
+ if (!img_request) {
+ result = -ENOMEM;
+ goto err_rq;
+ }
+ img_request->rq = rq;
+
down_read(&rbd_dev->header_rwsem);
mapping_size = rbd_dev->mapping.size;
- if (op_type != OBJ_OP_READ) {
- snapc = rbd_dev->header.snapc;
- ceph_get_snap_context(snapc);
- }
+ rbd_img_capture_header(img_request);
up_read(&rbd_dev->header_rwsem);
if (offset + length > mapping_size) {
rbd_warn(rbd_dev, "beyond EOD (%llu~%llu > %llu)", offset,
length, mapping_size);
result = -EIO;
- goto err_rq;
- }
-
- img_request = rbd_img_request_create(rbd_dev, op_type, snapc);
- if (!img_request) {
- result = -ENOMEM;
- goto err_rq;
+ goto err_img_request;
}
- img_request->rq = rq;
- snapc = NULL; /* img_request consumes a ref */
dout("%s rbd_dev %p img_req %p %s %llu~%llu\n", __func__, rbd_dev,
img_request, obj_op_name(op_type), offset, length);
@@ -4782,7 +4786,6 @@ static void rbd_queue_workfn(struct work_struct *work)
if (result)
rbd_warn(rbd_dev, "%s %llx at %llx result %d",
obj_op_name(op_type), length, offset, result);
- ceph_put_snap_context(snapc);
err:
blk_mq_end_request(rq, errno_to_blk_status(result));
}
Currently header_rwsem is acquired twice: once in rbd_dev_parent_get() when the image request is being created and then in rbd_queue_workfn() to capture mapping_size and snapc. Introduce rbd_img_capture_header() and move image request allocation so that header_rwsem can be acquired just once. Signed-off-by: Ilya Dryomov <idryomov@gmail.com> --- drivers/block/rbd.c | 59 ++++++++++++++++++++++++--------------------- 1 file changed, 31 insertions(+), 28 deletions(-)