Re: [PATCH 03/20] rbd: get rid of RBD_OBJ_WRITE_{FLAT,GUARD}

Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx> · Mon, 1 Jul 2019 13:28:17 +0800

On 06/25/2019 10:40 PM, Ilya Dryomov wrote:
In preparation for moving OSD request allocation and submission into
object request state machines, get rid of RBD_OBJ_WRITE_{FLAT,GUARD}.
We would need to start in a new state, whether the request is guarded
or not.  Unify them into RBD_OBJ_WRITE_OBJECT and pass guard info
through obj_req->flags.

While at it, make our ENOENT handling a little more precise: only hide
ENOENT when it is actually expected, that is on delete.

Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>

Reviewed-by: Dongsheng Yang <dongsheng.yang@xxxxxxxxxxxx>
---
  drivers/block/rbd.c | 112 ++++++++++++++++++++++++--------------------
  1 file changed, 60 insertions(+), 52 deletions(-)

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 7925b2fdde79..488da877a2bb 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -219,6 +219,9 @@ enum obj_operation_type {
  	OBJ_OP_ZEROOUT,
  };
  
+#define RBD_OBJ_FLAG_DELETION			(1U << 0)
+#define RBD_OBJ_FLAG_COPYUP_ENABLED		(1U << 1)
+
  enum rbd_obj_read_state {
  	RBD_OBJ_READ_OBJECT = 1,
  	RBD_OBJ_READ_PARENT,
@@ -250,8 +253,7 @@ enum rbd_obj_read_state {
   * even if there is a parent).
   */
  enum rbd_obj_write_state {
-	RBD_OBJ_WRITE_FLAT = 1,
-	RBD_OBJ_WRITE_GUARD,
+	RBD_OBJ_WRITE_OBJECT = 1,
  	RBD_OBJ_WRITE_READ_FROM_PARENT,
  	RBD_OBJ_WRITE_COPYUP_EMPTY_SNAPC,
  	RBD_OBJ_WRITE_COPYUP_OPS,
@@ -259,6 +261,7 @@ enum rbd_obj_write_state {
  
  struct rbd_obj_request {
  	struct ceph_object_extent ex;
+	unsigned int		flags;	/* RBD_OBJ_FLAG_* */
  	union {
  		enum rbd_obj_read_state	 read_state;	/* for reads */
  		enum rbd_obj_write_state write_state;	/* for writes */
@@ -1858,7 +1861,6 @@ static void __rbd_obj_setup_write(struct rbd_obj_request *obj_req,
  static int rbd_obj_setup_write(struct rbd_obj_request *obj_req)
  {
  	unsigned int num_osd_ops, which = 0;
-	bool need_guard;
  	int ret;
  
  	/* reverse map the entire object onto the parent */
@@ -1866,23 +1868,24 @@ static int rbd_obj_setup_write(struct rbd_obj_request *obj_req)
  	if (ret)
  		return ret;
  
-	need_guard = rbd_obj_copyup_enabled(obj_req);
-	num_osd_ops = need_guard + count_write_ops(obj_req);
+	if (rbd_obj_copyup_enabled(obj_req))
+		obj_req->flags |= RBD_OBJ_FLAG_COPYUP_ENABLED;
+
+	num_osd_ops = count_write_ops(obj_req);
+	if (obj_req->flags & RBD_OBJ_FLAG_COPYUP_ENABLED)
+		num_osd_ops++; /* stat */
  
  	obj_req->osd_req = rbd_osd_req_create(obj_req, num_osd_ops);
  	if (!obj_req->osd_req)
  		return -ENOMEM;
  
-	if (need_guard) {
+	if (obj_req->flags & RBD_OBJ_FLAG_COPYUP_ENABLED) {
  		ret = __rbd_obj_setup_stat(obj_req, which++);
  		if (ret)
  			return ret;
-
-		obj_req->write_state = RBD_OBJ_WRITE_GUARD;
-	} else {
-		obj_req->write_state = RBD_OBJ_WRITE_FLAT;
  	}
  
+	obj_req->write_state = RBD_OBJ_WRITE_OBJECT;
  	__rbd_obj_setup_write(obj_req, which);
  	return 0;
  }
@@ -1921,11 +1924,15 @@ static int rbd_obj_setup_discard(struct rbd_obj_request *obj_req)
  	if (ret)
  		return ret;
  
+	if (rbd_obj_is_entire(obj_req) && !obj_req->num_img_extents)
+		obj_req->flags |= RBD_OBJ_FLAG_DELETION;
+
  	obj_req->osd_req = rbd_osd_req_create(obj_req, 1);
  	if (!obj_req->osd_req)
  		return -ENOMEM;
  
  	if (rbd_obj_is_entire(obj_req) && !obj_req->num_img_extents) {
+		rbd_assert(obj_req->flags & RBD_OBJ_FLAG_DELETION);
  		osd_req_op_init(obj_req->osd_req, 0, CEPH_OSD_OP_DELETE, 0);
  	} else {
  		dout("%s %p %llu~%llu -> %llu~%llu\n", __func__,
@@ -1936,7 +1943,7 @@ static int rbd_obj_setup_discard(struct rbd_obj_request *obj_req)
  				       off, next_off - off, 0, 0);
  	}
  
-	obj_req->write_state = RBD_OBJ_WRITE_FLAT;
+	obj_req->write_state = RBD_OBJ_WRITE_OBJECT;
  	rbd_osd_req_format_write(obj_req);
  	return 0;
  }
@@ -1961,11 +1968,12 @@ static void __rbd_obj_setup_zeroout(struct rbd_obj_request *obj_req,
  
  	if (rbd_obj_is_entire(obj_req)) {
  		if (obj_req->num_img_extents) {
-			if (!rbd_obj_copyup_enabled(obj_req))
+			if (!(obj_req->flags & RBD_OBJ_FLAG_COPYUP_ENABLED))
  				osd_req_op_init(obj_req->osd_req, which++,
  						CEPH_OSD_OP_CREATE, 0);
  			opcode = CEPH_OSD_OP_TRUNCATE;
  		} else {
+			rbd_assert(obj_req->flags & RBD_OBJ_FLAG_DELETION);
  			osd_req_op_init(obj_req->osd_req, which++,
  					CEPH_OSD_OP_DELETE, 0);
  			opcode = 0;
@@ -1986,7 +1994,6 @@ static void __rbd_obj_setup_zeroout(struct rbd_obj_request *obj_req,
  static int rbd_obj_setup_zeroout(struct rbd_obj_request *obj_req)
  {
  	unsigned int num_osd_ops, which = 0;
-	bool need_guard;
  	int ret;
  
  	/* reverse map the entire object onto the parent */
@@ -1994,23 +2001,28 @@ static int rbd_obj_setup_zeroout(struct rbd_obj_request *obj_req)
  	if (ret)
  		return ret;
  
-	need_guard = rbd_obj_copyup_enabled(obj_req);
-	num_osd_ops = need_guard + count_zeroout_ops(obj_req);
+	if (rbd_obj_copyup_enabled(obj_req))
+		obj_req->flags |= RBD_OBJ_FLAG_COPYUP_ENABLED;
+	if (!obj_req->num_img_extents) {
+		if (rbd_obj_is_entire(obj_req))
+			obj_req->flags |= RBD_OBJ_FLAG_DELETION;
+	}
+
+	num_osd_ops = count_zeroout_ops(obj_req);
+	if (obj_req->flags & RBD_OBJ_FLAG_COPYUP_ENABLED)
+		num_osd_ops++; /* stat */
  
  	obj_req->osd_req = rbd_osd_req_create(obj_req, num_osd_ops);
  	if (!obj_req->osd_req)
  		return -ENOMEM;
  
-	if (need_guard) {
+	if (obj_req->flags & RBD_OBJ_FLAG_COPYUP_ENABLED) {
  		ret = __rbd_obj_setup_stat(obj_req, which++);
  		if (ret)
  			return ret;
-
-		obj_req->write_state = RBD_OBJ_WRITE_GUARD;
-	} else {
-		obj_req->write_state = RBD_OBJ_WRITE_FLAT;
  	}
  
+	obj_req->write_state = RBD_OBJ_WRITE_OBJECT;
  	__rbd_obj_setup_zeroout(obj_req, which);
  	return 0;
  }
@@ -2617,6 +2629,11 @@ static int setup_copyup_bvecs(struct rbd_obj_request *obj_req, u64 obj_overlap)
  	return 0;
  }
  
+/*
+ * The target object doesn't exist.  Read the data for the entire
+ * target object up to the overlap point (if any) from the parent,
+ * so we can use it for a copyup.
+ */
  static int rbd_obj_handle_write_guard(struct rbd_obj_request *obj_req)
  {
  	struct rbd_device *rbd_dev = obj_req->img_request->rbd_dev;
@@ -2649,22 +2666,24 @@ static bool rbd_obj_handle_write(struct rbd_obj_request *obj_req, int *result)
  	int ret;
  
  	switch (obj_req->write_state) {
-	case RBD_OBJ_WRITE_GUARD:
+	case RBD_OBJ_WRITE_OBJECT:
  		if (*result == -ENOENT) {
+			if (obj_req->flags & RBD_OBJ_FLAG_COPYUP_ENABLED) {
+				ret = rbd_obj_handle_write_guard(obj_req);
+				if (ret) {
+					*result = ret;
+					return true;
+				}
+				return false;
+			}
  			/*
-			 * The target object doesn't exist.  Read the data for
-			 * the entire target object up to the overlap point (if
-			 * any) from the parent, so we can use it for a copyup.
+			 * On a non-existent object:
+			 *   delete - -ENOENT, truncate/zero - 0
  			 */
-			ret = rbd_obj_handle_write_guard(obj_req);
-			if (ret) {
-				*result = ret;
-				return true;
-			}
-			return false;
+			if (obj_req->flags & RBD_OBJ_FLAG_DELETION)
+				*result = 0;
  		}
  		/* fall through */
-	case RBD_OBJ_WRITE_FLAT:
  	case RBD_OBJ_WRITE_COPYUP_OPS:
  		return true;
  	case RBD_OBJ_WRITE_READ_FROM_PARENT:
@@ -2695,31 +2714,20 @@ static bool rbd_obj_handle_write(struct rbd_obj_request *obj_req, int *result)
  }
  
  /*
- * Returns true if @obj_req is completed, or false otherwise.
+ * Return true if @obj_req is completed.
   */
  static bool __rbd_obj_handle_request(struct rbd_obj_request *obj_req,
  				     int *result)
  {
-	switch (obj_req->img_request->op_type) {
-	case OBJ_OP_READ:
-		return rbd_obj_handle_read(obj_req, result);
-	case OBJ_OP_WRITE:
-		return rbd_obj_handle_write(obj_req, result);
-	case OBJ_OP_DISCARD:
-	case OBJ_OP_ZEROOUT:
-		if (rbd_obj_handle_write(obj_req, result)) {
-			/*
-			 * Hide -ENOENT from delete/truncate/zero -- discarding
-			 * a non-existent object is not a problem.
-			 */
-			if (*result == -ENOENT)
-				*result = 0;
-			return true;
-		}
-		return false;
-	default:
-		BUG();
-	}
+	struct rbd_img_request *img_req = obj_req->img_request;
+	bool done;
+
+	if (!rbd_img_is_write(img_req))
+		done = rbd_obj_handle_read(obj_req, result);
+	else
+		done = rbd_obj_handle_write(obj_req, result);
+
+	return done;
  }
  
  static void rbd_obj_end_request(struct rbd_obj_request *obj_req, int result)








