rbd: introduce image request state machine
Make it possible to schedule image requests on a workqueue. This fixes parent chain recursion added in the previous commit and lays the ground for exclusive lock wait/wake improvements. The "wait for pending subrequests and report first nonzero result" code is generalized to be used by object request state machine. Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Reviewed-by: Dongsheng Yang <dongsheng.yang@easystack.cn>
This commit is contained in:
Ilya Dryomov
parent
85b5e6d118
commit
0192ce2ee6
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@ -203,6 +203,11 @@ struct rbd_client {
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struct list_head node;
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};
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struct pending_result {
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int result; /* first nonzero result */
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int num_pending;
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};
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struct rbd_img_request;
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enum obj_request_type {
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@ -295,11 +300,18 @@ enum img_req_flags {
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IMG_REQ_LAYERED, /* ENOENT handling: normal = 0, layered = 1 */
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};
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enum rbd_img_state {
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RBD_IMG_START = 1,
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__RBD_IMG_OBJECT_REQUESTS,
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RBD_IMG_OBJECT_REQUESTS,
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};
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struct rbd_img_request {
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struct rbd_device *rbd_dev;
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enum obj_operation_type op_type;
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enum obj_request_type data_type;
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unsigned long flags;
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enum rbd_img_state state;
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union {
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u64 snap_id; /* for reads */
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struct ceph_snap_context *snapc; /* for writes */
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@ -308,12 +320,13 @@ struct rbd_img_request {
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struct request *rq; /* block request */
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struct rbd_obj_request *obj_request; /* obj req initiator */
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};
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spinlock_t completion_lock;
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int result; /* first nonzero obj_request result */
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struct list_head object_extents; /* obj_req.ex structs */
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u32 pending_count;
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struct mutex state_mutex;
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struct pending_result pending;
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struct work_struct work;
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int work_result;
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struct kref kref;
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};
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@ -592,6 +605,23 @@ static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
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u64 *snap_features);
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static void rbd_obj_handle_request(struct rbd_obj_request *obj_req, int result);
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static void rbd_img_handle_request(struct rbd_img_request *img_req, int result);
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/*
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* Return true if nothing else is pending.
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*/
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static bool pending_result_dec(struct pending_result *pending, int *result)
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{
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rbd_assert(pending->num_pending > 0);
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if (*result && !pending->result)
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pending->result = *result;
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if (--pending->num_pending)
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return false;
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*result = pending->result;
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return true;
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}
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static int rbd_open(struct block_device *bdev, fmode_t mode)
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{
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@ -1350,13 +1380,6 @@ static void rbd_obj_request_put(struct rbd_obj_request *obj_request)
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kref_put(&obj_request->kref, rbd_obj_request_destroy);
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}
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static void rbd_img_request_get(struct rbd_img_request *img_request)
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{
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dout("%s: img %p (was %d)\n", __func__, img_request,
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kref_read(&img_request->kref));
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kref_get(&img_request->kref);
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}
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static void rbd_img_request_destroy(struct kref *kref);
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static void rbd_img_request_put(struct rbd_img_request *img_request)
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{
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@ -1373,7 +1396,6 @@ static inline void rbd_img_obj_request_add(struct rbd_img_request *img_request,
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/* Image request now owns object's original reference */
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obj_request->img_request = img_request;
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img_request->pending_count++;
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dout("%s: img %p obj %p\n", __func__, img_request, obj_request);
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}
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@ -1694,8 +1716,8 @@ static struct rbd_img_request *rbd_img_request_create(
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if (rbd_dev_parent_get(rbd_dev))
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img_request_layered_set(img_request);
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spin_lock_init(&img_request->completion_lock);
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INIT_LIST_HEAD(&img_request->object_extents);
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mutex_init(&img_request->state_mutex);
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kref_init(&img_request->kref);
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dout("%s: rbd_dev %p %s -> img %p\n", __func__, rbd_dev,
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@ -2061,7 +2083,6 @@ static int __rbd_img_fill_request(struct rbd_img_request *img_req)
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if (ret < 0)
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return ret;
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if (ret > 0) {
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img_req->pending_count--;
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rbd_img_obj_request_del(img_req, obj_req);
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continue;
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}
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@ -2071,6 +2092,7 @@ static int __rbd_img_fill_request(struct rbd_img_request *img_req)
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return ret;
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}
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img_req->state = RBD_IMG_START;
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return 0;
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}
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@ -2359,17 +2381,19 @@ static int rbd_img_fill_from_bvecs(struct rbd_img_request *img_req,
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&it);
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}
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static void rbd_img_request_submit(struct rbd_img_request *img_request)
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static void rbd_img_handle_request_work(struct work_struct *work)
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{
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struct rbd_obj_request *obj_request;
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struct rbd_img_request *img_req =
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container_of(work, struct rbd_img_request, work);
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dout("%s: img %p\n", __func__, img_request);
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rbd_img_handle_request(img_req, img_req->work_result);
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}
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rbd_img_request_get(img_request);
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for_each_obj_request(img_request, obj_request)
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rbd_obj_handle_request(obj_request, 0);
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rbd_img_request_put(img_request);
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static void rbd_img_schedule(struct rbd_img_request *img_req, int result)
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{
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INIT_WORK(&img_req->work, rbd_img_handle_request_work);
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img_req->work_result = result;
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queue_work(rbd_wq, &img_req->work);
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}
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static int rbd_obj_read_object(struct rbd_obj_request *obj_req)
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@ -2421,7 +2445,8 @@ static int rbd_obj_read_from_parent(struct rbd_obj_request *obj_req)
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return ret;
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}
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rbd_img_request_submit(child_img_req);
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/* avoid parent chain recursion */
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rbd_img_schedule(child_img_req, 0);
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return 0;
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}
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@ -2756,6 +2781,7 @@ static bool __rbd_obj_handle_request(struct rbd_obj_request *obj_req,
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int *result)
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{
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struct rbd_img_request *img_req = obj_req->img_request;
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struct rbd_device *rbd_dev = img_req->rbd_dev;
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bool done;
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mutex_lock(&obj_req->state_mutex);
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@ -2765,59 +2791,113 @@ static bool __rbd_obj_handle_request(struct rbd_obj_request *obj_req,
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done = rbd_obj_advance_write(obj_req, result);
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mutex_unlock(&obj_req->state_mutex);
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if (done && *result) {
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rbd_assert(*result < 0);
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rbd_warn(rbd_dev, "%s at objno %llu %llu~%llu result %d",
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obj_op_name(img_req->op_type), obj_req->ex.oe_objno,
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obj_req->ex.oe_off, obj_req->ex.oe_len, *result);
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}
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return done;
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}
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static void rbd_obj_end_request(struct rbd_obj_request *obj_req, int result)
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{
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struct rbd_img_request *img_req = obj_req->img_request;
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rbd_assert(result <= 0);
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if (!result)
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return;
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rbd_warn(img_req->rbd_dev, "%s at objno %llu %llu~%llu result %d",
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obj_op_name(img_req->op_type), obj_req->ex.oe_objno,
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obj_req->ex.oe_off, obj_req->ex.oe_len, result);
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if (!img_req->result)
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img_req->result = result;
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}
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static void rbd_img_end_request(struct rbd_img_request *img_req)
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{
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rbd_assert(!test_bit(IMG_REQ_CHILD, &img_req->flags));
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blk_mq_end_request(img_req->rq,
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errno_to_blk_status(img_req->result));
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rbd_img_request_put(img_req);
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}
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/*
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* This is open-coded in rbd_img_handle_request() to avoid parent chain
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* recursion.
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*/
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static void rbd_obj_handle_request(struct rbd_obj_request *obj_req, int result)
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{
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struct rbd_img_request *img_req;
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if (__rbd_obj_handle_request(obj_req, &result))
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rbd_img_handle_request(obj_req->img_request, result);
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}
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static void rbd_img_object_requests(struct rbd_img_request *img_req)
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{
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struct rbd_obj_request *obj_req;
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rbd_assert(!img_req->pending.result && !img_req->pending.num_pending);
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for_each_obj_request(img_req, obj_req) {
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int result = 0;
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if (__rbd_obj_handle_request(obj_req, &result)) {
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if (result) {
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img_req->pending.result = result;
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return;
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}
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} else {
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img_req->pending.num_pending++;
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}
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}
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}
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static bool rbd_img_advance(struct rbd_img_request *img_req, int *result)
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{
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again:
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if (!__rbd_obj_handle_request(obj_req, &result))
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return;
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switch (img_req->state) {
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case RBD_IMG_START:
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rbd_assert(!*result);
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img_req = obj_req->img_request;
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spin_lock(&img_req->completion_lock);
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rbd_obj_end_request(obj_req, result);
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rbd_assert(img_req->pending_count);
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if (--img_req->pending_count) {
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spin_unlock(&img_req->completion_lock);
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return;
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rbd_img_object_requests(img_req);
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if (!img_req->pending.num_pending) {
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*result = img_req->pending.result;
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img_req->state = RBD_IMG_OBJECT_REQUESTS;
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goto again;
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}
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img_req->state = __RBD_IMG_OBJECT_REQUESTS;
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return false;
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case __RBD_IMG_OBJECT_REQUESTS:
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if (!pending_result_dec(&img_req->pending, result))
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return false;
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/* fall through */
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case RBD_IMG_OBJECT_REQUESTS:
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return true;
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default:
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BUG();
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}
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}
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/*
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* Return true if @img_req is completed.
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*/
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static bool __rbd_img_handle_request(struct rbd_img_request *img_req,
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int *result)
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{
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struct rbd_device *rbd_dev = img_req->rbd_dev;
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bool done;
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mutex_lock(&img_req->state_mutex);
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done = rbd_img_advance(img_req, result);
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mutex_unlock(&img_req->state_mutex);
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if (done && *result) {
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rbd_assert(*result < 0);
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rbd_warn(rbd_dev, "%s%s result %d",
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test_bit(IMG_REQ_CHILD, &img_req->flags) ? "child " : "",
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obj_op_name(img_req->op_type), *result);
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}
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return done;
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}
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static void rbd_img_handle_request(struct rbd_img_request *img_req, int result)
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{
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again:
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if (!__rbd_img_handle_request(img_req, &result))
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return;
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spin_unlock(&img_req->completion_lock);
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rbd_assert(img_req->result <= 0);
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if (test_bit(IMG_REQ_CHILD, &img_req->flags)) {
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obj_req = img_req->obj_request;
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result = img_req->result;
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struct rbd_obj_request *obj_req = img_req->obj_request;
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rbd_img_request_put(img_req);
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goto again;
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if (__rbd_obj_handle_request(obj_req, &result)) {
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img_req = obj_req->img_request;
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goto again;
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}
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} else {
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struct request *rq = img_req->rq;
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rbd_img_request_put(img_req);
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blk_mq_end_request(rq, errno_to_blk_status(result));
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}
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rbd_img_end_request(img_req);
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}
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static const struct rbd_client_id rbd_empty_cid;
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@ -3933,10 +4013,10 @@ static void rbd_queue_workfn(struct work_struct *work)
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else
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result = rbd_img_fill_from_bio(img_request, offset, length,
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rq->bio);
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if (result || !img_request->pending_count)
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if (result)
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goto err_img_request;
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rbd_img_request_submit(img_request);
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rbd_img_handle_request(img_request, 0);
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if (must_be_locked)
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up_read(&rbd_dev->lock_rwsem);
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return;
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