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authorIlya Dryomov <idryomov@gmail.com>2019-05-16 15:06:56 +0200
committerIlya Dryomov <idryomov@gmail.com>2019-07-08 14:01:44 +0200
commit0192ce2ee68b54394ba62e5668067bf01f7bc609 (patch)
treee6f3c9ff14cb9c081f12381b3cc854390d66cb58 /drivers/block
parent85b5e6d11898fddfcb2832024f73454d448f76e0 (diff)
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>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/rbd.c194
1 files changed, 137 insertions, 57 deletions
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 9c6be82353c0..51dd1b99c242 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -203,6 +203,11 @@ struct rbd_client {
struct list_head node;
};
+struct pending_result {
+ int result; /* first nonzero result */
+ int num_pending;
+};
+
struct rbd_img_request;
enum obj_request_type {
@@ -295,11 +300,18 @@ enum img_req_flags {
IMG_REQ_LAYERED, /* ENOENT handling: normal = 0, layered = 1 */
};
+enum rbd_img_state {
+ RBD_IMG_START = 1,
+ __RBD_IMG_OBJECT_REQUESTS,
+ RBD_IMG_OBJECT_REQUESTS,
+};
+
struct rbd_img_request {
struct rbd_device *rbd_dev;
enum obj_operation_type op_type;
enum obj_request_type data_type;
unsigned long flags;
+ enum rbd_img_state state;
union {
u64 snap_id; /* for reads */
struct ceph_snap_context *snapc; /* for writes */
@@ -308,12 +320,13 @@ struct rbd_img_request {
struct request *rq; /* block request */
struct rbd_obj_request *obj_request; /* obj req initiator */
};
- spinlock_t completion_lock;
- int result; /* first nonzero obj_request result */
struct list_head object_extents; /* obj_req.ex structs */
- u32 pending_count;
+ struct mutex state_mutex;
+ struct pending_result pending;
+ struct work_struct work;
+ int work_result;
struct kref kref;
};
@@ -592,6 +605,23 @@ static int _rbd_dev_v2_snap_features(struct rbd_device *rbd_dev, u64 snap_id,
u64 *snap_features);
static void rbd_obj_handle_request(struct rbd_obj_request *obj_req, int result);
+static void rbd_img_handle_request(struct rbd_img_request *img_req, int result);
+
+/*
+ * Return true if nothing else is pending.
+ */
+static bool pending_result_dec(struct pending_result *pending, int *result)
+{
+ rbd_assert(pending->num_pending > 0);
+
+ if (*result && !pending->result)
+ pending->result = *result;
+ if (--pending->num_pending)
+ return false;
+
+ *result = pending->result;
+ return true;
+}
static int rbd_open(struct block_device *bdev, fmode_t mode)
{
@@ -1350,13 +1380,6 @@ static void rbd_obj_request_put(struct rbd_obj_request *obj_request)
kref_put(&obj_request->kref, rbd_obj_request_destroy);
}
-static void rbd_img_request_get(struct rbd_img_request *img_request)
-{
- dout("%s: img %p (was %d)\n", __func__, img_request,
- kref_read(&img_request->kref));
- kref_get(&img_request->kref);
-}
-
static void rbd_img_request_destroy(struct kref *kref);
static void rbd_img_request_put(struct rbd_img_request *img_request)
{
@@ -1373,7 +1396,6 @@ static inline void rbd_img_obj_request_add(struct rbd_img_request *img_request,
/* Image request now owns object's original reference */
obj_request->img_request = img_request;
- img_request->pending_count++;
dout("%s: img %p obj %p\n", __func__, img_request, obj_request);
}
@@ -1694,8 +1716,8 @@ static struct rbd_img_request *rbd_img_request_create(
if (rbd_dev_parent_get(rbd_dev))
img_request_layered_set(img_request);
- spin_lock_init(&img_request->completion_lock);
INIT_LIST_HEAD(&img_request->object_extents);
+ mutex_init(&img_request->state_mutex);
kref_init(&img_request->kref);
dout("%s: rbd_dev %p %s -> img %p\n", __func__, rbd_dev,
@@ -2061,7 +2083,6 @@ static int __rbd_img_fill_request(struct rbd_img_request *img_req)
if (ret < 0)
return ret;
if (ret > 0) {
- img_req->pending_count--;
rbd_img_obj_request_del(img_req, obj_req);
continue;
}
@@ -2071,6 +2092,7 @@ static int __rbd_img_fill_request(struct rbd_img_request *img_req)
return ret;
}
+ img_req->state = RBD_IMG_START;
return 0;
}
@@ -2359,17 +2381,19 @@ static int rbd_img_fill_from_bvecs(struct rbd_img_request *img_req,
&it);
}
-static void rbd_img_request_submit(struct rbd_img_request *img_request)
+static void rbd_img_handle_request_work(struct work_struct *work)
{
- struct rbd_obj_request *obj_request;
+ struct rbd_img_request *img_req =
+ container_of(work, struct rbd_img_request, work);
- dout("%s: img %p\n", __func__, img_request);
-
- rbd_img_request_get(img_request);
- for_each_obj_request(img_request, obj_request)
- rbd_obj_handle_request(obj_request, 0);
+ rbd_img_handle_request(img_req, img_req->work_result);
+}
- rbd_img_request_put(img_request);
+static void rbd_img_schedule(struct rbd_img_request *img_req, int result)
+{
+ INIT_WORK(&img_req->work, rbd_img_handle_request_work);
+ img_req->work_result = result;
+ queue_work(rbd_wq, &img_req->work);
}
static int rbd_obj_read_object(struct rbd_obj_request *obj_req)
@@ -2421,7 +2445,8 @@ static int rbd_obj_read_from_parent(struct rbd_obj_request *obj_req)
return ret;
}
- rbd_img_request_submit(child_img_req);
+ /* avoid parent chain recursion */
+ rbd_img_schedule(child_img_req, 0);
return 0;
}
@@ -2756,6 +2781,7 @@ static bool __rbd_obj_handle_request(struct rbd_obj_request *obj_req,
int *result)
{
struct rbd_img_request *img_req = obj_req->img_request;
+ struct rbd_device *rbd_dev = img_req->rbd_dev;
bool done;
mutex_lock(&obj_req->state_mutex);
@@ -2765,59 +2791,113 @@ static bool __rbd_obj_handle_request(struct rbd_obj_request *obj_req,
done = rbd_obj_advance_write(obj_req, result);
mutex_unlock(&obj_req->state_mutex);
+ if (done && *result) {
+ rbd_assert(*result < 0);
+ rbd_warn(rbd_dev, "%s at objno %llu %llu~%llu result %d",
+ obj_op_name(img_req->op_type), obj_req->ex.oe_objno,
+ obj_req->ex.oe_off, obj_req->ex.oe_len, *result);
+ }
return done;
}
-static void rbd_obj_end_request(struct rbd_obj_request *obj_req, int result)
+/*
+ * This is open-coded in rbd_img_handle_request() to avoid parent chain
+ * recursion.
+ */
+static void rbd_obj_handle_request(struct rbd_obj_request *obj_req, int result)
+{
+ if (__rbd_obj_handle_request(obj_req, &result))
+ rbd_img_handle_request(obj_req->img_request, result);
+}
+
+static void rbd_img_object_requests(struct rbd_img_request *img_req)
{
- struct rbd_img_request *img_req = obj_req->img_request;
+ struct rbd_obj_request *obj_req;
- rbd_assert(result <= 0);
- if (!result)
- return;
+ rbd_assert(!img_req->pending.result && !img_req->pending.num_pending);
+
+ for_each_obj_request(img_req, obj_req) {
+ int result = 0;
- rbd_warn(img_req->rbd_dev, "%s at objno %llu %llu~%llu result %d",
- obj_op_name(img_req->op_type), obj_req->ex.oe_objno,
- obj_req->ex.oe_off, obj_req->ex.oe_len, result);
- if (!img_req->result)
- img_req->result = result;
+ if (__rbd_obj_handle_request(obj_req, &result)) {
+ if (result) {
+ img_req->pending.result = result;
+ return;
+ }
+ } else {
+ img_req->pending.num_pending++;
+ }
+ }
}
-static void rbd_img_end_request(struct rbd_img_request *img_req)
+static bool rbd_img_advance(struct rbd_img_request *img_req, int *result)
{
- rbd_assert(!test_bit(IMG_REQ_CHILD, &img_req->flags));
+again:
+ switch (img_req->state) {
+ case RBD_IMG_START:
+ rbd_assert(!*result);
- blk_mq_end_request(img_req->rq,
- errno_to_blk_status(img_req->result));
- rbd_img_request_put(img_req);
+ rbd_img_object_requests(img_req);
+ if (!img_req->pending.num_pending) {
+ *result = img_req->pending.result;
+ img_req->state = RBD_IMG_OBJECT_REQUESTS;
+ goto again;
+ }
+ img_req->state = __RBD_IMG_OBJECT_REQUESTS;
+ return false;
+ case __RBD_IMG_OBJECT_REQUESTS:
+ if (!pending_result_dec(&img_req->pending, result))
+ return false;
+ /* fall through */
+ case RBD_IMG_OBJECT_REQUESTS:
+ return true;
+ default:
+ BUG();
+ }
}
-static void rbd_obj_handle_request(struct rbd_obj_request *obj_req, int result)
+/*
+ * Return true if @img_req is completed.
+ */
+static bool __rbd_img_handle_request(struct rbd_img_request *img_req,
+ int *result)
{
- struct rbd_img_request *img_req;
+ struct rbd_device *rbd_dev = img_req->rbd_dev;
+ bool done;
-again:
- if (!__rbd_obj_handle_request(obj_req, &result))
- return;
+ mutex_lock(&img_req->state_mutex);
+ done = rbd_img_advance(img_req, result);
+ mutex_unlock(&img_req->state_mutex);
- img_req = obj_req->img_request;
- spin_lock(&img_req->completion_lock);
- rbd_obj_end_request(obj_req, result);
- rbd_assert(img_req->pending_count);
- if (--img_req->pending_count) {
- spin_unlock(&img_req->completion_lock);
- return;
+ if (done && *result) {
+ rbd_assert(*result < 0);
+ rbd_warn(rbd_dev, "%s%s result %d",
+ test_bit(IMG_REQ_CHILD, &img_req->flags) ? "child " : "",
+ obj_op_name(img_req->op_type), *result);
}
+ return done;
+}
+
+static void rbd_img_handle_request(struct rbd_img_request *img_req, int result)
+{
+again:
+ if (!__rbd_img_handle_request(img_req, &result))
+ return;
- spin_unlock(&img_req->completion_lock);
- rbd_assert(img_req->result <= 0);
if (test_bit(IMG_REQ_CHILD, &img_req->flags)) {
- obj_req = img_req->obj_request;
- result = img_req->result;
+ struct rbd_obj_request *obj_req = img_req->obj_request;
+
rbd_img_request_put(img_req);
- goto again;
+ if (__rbd_obj_handle_request(obj_req, &result)) {
+ img_req = obj_req->img_request;
+ goto again;
+ }
+ } else {
+ struct request *rq = img_req->rq;
+
+ rbd_img_request_put(img_req);
+ blk_mq_end_request(rq, errno_to_blk_status(result));
}
- rbd_img_end_request(img_req);
}
static const struct rbd_client_id rbd_empty_cid;
@@ -3933,10 +4013,10 @@ static void rbd_queue_workfn(struct work_struct *work)
else
result = rbd_img_fill_from_bio(img_request, offset, length,
rq->bio);
- if (result || !img_request->pending_count)
+ if (result)
goto err_img_request;
- rbd_img_request_submit(img_request);
+ rbd_img_handle_request(img_request, 0);
if (must_be_locked)
up_read(&rbd_dev->lock_rwsem);
return;