On 06/25/2019 10:40 PM, Ilya Dryomov wrote:
Make rbd_obj_handle_read() look like a state machine and get rid of
the necessity to patch result in rbd_obj_handle_request(), completing
the removal of obj_req->xferred and img_req->xferred.
Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
---
drivers/block/rbd.c | 82 +++++++++++++++++++++++++--------------------
1 file changed, 46 insertions(+), 36 deletions(-)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index a9b0b23148f9..7925b2fdde79 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -219,6 +219,11 @@ enum obj_operation_type {
OBJ_OP_ZEROOUT,
};
+enum rbd_obj_read_state {
+ RBD_OBJ_READ_OBJECT = 1,
+ RBD_OBJ_READ_PARENT,
+};
+
/*
* Writes go through the following state machine to deal with
* layering:
@@ -255,7 +260,7 @@ enum rbd_obj_write_state {
struct rbd_obj_request {
struct ceph_object_extent ex;
union {
- bool tried_parent; /* for reads */
+ enum rbd_obj_read_state read_state; /* for reads */
enum rbd_obj_write_state write_state; /* for writes */
};
@@ -1794,6 +1799,7 @@ static int rbd_obj_setup_read(struct rbd_obj_request *obj_req)
rbd_osd_req_setup_data(obj_req, 0);
rbd_osd_req_format_read(obj_req);
+ obj_req->read_state = RBD_OBJ_READ_OBJECT;
return 0;
}
@@ -2402,44 +2408,48 @@ static bool rbd_obj_handle_read(struct rbd_obj_request *obj_req, int *result)
struct rbd_device *rbd_dev = obj_req->img_request->rbd_dev;
int ret;
- if (*result == -ENOENT &&
- rbd_dev->parent_overlap && !obj_req->tried_parent) {
- /* reverse map this object extent onto the parent */
- ret = rbd_obj_calc_img_extents(obj_req, false);
- if (ret) {
- *result = ret;
- return true;
- }
-
- if (obj_req->num_img_extents) {
- obj_req->tried_parent = true;
- ret = rbd_obj_read_from_parent(obj_req);
+ switch (obj_req->read_state) {
+ case RBD_OBJ_READ_OBJECT:
+ if (*result == -ENOENT && rbd_dev->parent_overlap) {
+ /* reverse map this object extent onto the parent */
+ ret = rbd_obj_calc_img_extents(obj_req, false);
if (ret) {
*result = ret;
return true;
}
- return false;
+ if (obj_req->num_img_extents) {
+ ret = rbd_obj_read_from_parent(obj_req);
+ if (ret) {
+ *result = ret;
+ return true;
+ }
+ obj_req->read_state = RBD_OBJ_READ_PARENT;
Seems there is a race window between the read request complete but the
read_state is still RBD_OBJ_READ_OBJECT.
+ return false;
+ }
}
- }
- /*
- * -ENOENT means a hole in the image -- zero-fill the entire
- * length of the request. A short read also implies zero-fill
- * to the end of the request.
- */
- if (*result == -ENOENT) {
- rbd_obj_zero_range(obj_req, 0, obj_req->ex.oe_len);
- *result = 0;
- } else if (*result >= 0) {
- if (*result < obj_req->ex.oe_len)
- rbd_obj_zero_range(obj_req, *result,
- obj_req->ex.oe_len - *result);
- else
- rbd_assert(*result == obj_req->ex.oe_len);
- *result = 0;
+ /*
+ * -ENOENT means a hole in the image -- zero-fill the entire
+ * length of the request. A short read also implies zero-fill
+ * to the end of the request.
+ */
+ if (*result == -ENOENT) {
+ rbd_obj_zero_range(obj_req, 0, obj_req->ex.oe_len);
+ *result = 0;
+ } else if (*result >= 0) {
+ if (*result < obj_req->ex.oe_len)
+ rbd_obj_zero_range(obj_req, *result,
+ obj_req->ex.oe_len - *result);
+ else
+ rbd_assert(*result == obj_req->ex.oe_len);
+ *result = 0;
+ }
+ return true;
+ case RBD_OBJ_READ_PARENT:
+ return true;
+ default:
+ BUG();
}
-
- return true;
}
/*
@@ -2658,11 +2668,11 @@ static bool rbd_obj_handle_write(struct rbd_obj_request *obj_req, int *result)
case RBD_OBJ_WRITE_COPYUP_OPS:
return true;
case RBD_OBJ_WRITE_READ_FROM_PARENT:
- if (*result < 0)
+ if (*result)
return true;
- rbd_assert(*result);
- ret = rbd_obj_issue_copyup(obj_req, *result);
+ ret = rbd_obj_issue_copyup(obj_req,
+ rbd_obj_img_extents_bytes(obj_req));
if (ret) {
*result = ret;
return true;
@@ -2757,7 +2767,7 @@ static void rbd_obj_handle_request(struct rbd_obj_request *obj_req, int result)
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 ?: rbd_obj_img_extents_bytes(obj_req);
+ result = img_req->result;
rbd_img_request_put(img_req);
goto again;
}
should this part be in 01/20 ?
Thanx
