Commit 5679c59f authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

rbd: add target object existence flags 



This creates two new flags for object requests to indicate what is
known about the existence of the object to which a request is to be
sent.  The KNOWN flag will be true if the the EXISTS flag is
meaningful.  That is:

    KNOWN   EXISTS
    -----   ------
      0       0     don't know whether the object exists
      0       1     (not used/invalid)
      1       0     object is known to not exist
      1       0     object is known to exist

This will be used in determining how to handle write requests for
data objects for layered rbd images.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 57acbaa7

drivers/block/rbd.c

+37 −0
Original line number Diff line number Diff line
@@ -173,6 +173,8 @@ enum obj_request_type { 
enum obj_req_flags {

	OBJ_REQ_DONE,		/* completion flag: not done = 0, done = 1 */

	OBJ_REQ_IMG_DATA,	/* object usage: standalone = 0, image = 1 */

	OBJ_REQ_KNOWN,		/* EXISTS flag valid: no = 0, yes = 1 */

	OBJ_REQ_EXISTS,		/* target exists: no = 0, yes = 1 */

};



struct rbd_obj_request {
@@ -1129,6 +1131,37 @@ static bool obj_request_done_test(struct rbd_obj_request *obj_request) 
	return test_bit(OBJ_REQ_DONE, &obj_request->flags) != 0;

}



/*

 * This sets the KNOWN flag after (possibly) setting the EXISTS

 * flag.  The latter is set based on the "exists" value provided.

 *

 * Note that for our purposes once an object exists it never goes

 * away again.  It's possible that the response from two existence

 * checks are separated by the creation of the target object, and

 * the first ("doesn't exist") response arrives *after* the second

 * ("does exist").  In that case we ignore the second one.

 */

static void obj_request_existence_set(struct rbd_obj_request *obj_request,

				bool exists)

{

	if (exists)

		set_bit(OBJ_REQ_EXISTS, &obj_request->flags);

	set_bit(OBJ_REQ_KNOWN, &obj_request->flags);

	smp_mb();

}



static bool obj_request_known_test(struct rbd_obj_request *obj_request)

{

	smp_mb();

	return test_bit(OBJ_REQ_KNOWN, &obj_request->flags) != 0;

}



static bool obj_request_exists_test(struct rbd_obj_request *obj_request)

{

	smp_mb();

	return test_bit(OBJ_REQ_EXISTS, &obj_request->flags) != 0;

}



static void rbd_obj_request_get(struct rbd_obj_request *obj_request)

{

	dout("%s: obj %p (was %d)\n", __func__, obj_request,
@@ -1623,6 +1656,10 @@ static struct rbd_img_request *rbd_img_request_create( 
	INIT_LIST_HEAD(&img_request->obj_requests);

	kref_init(&img_request->kref);



	(void) obj_request_existence_set;

	(void) obj_request_known_test;

	(void) obj_request_exists_test;



	rbd_img_request_get(img_request);	/* Avoid a warning */

	rbd_img_request_put(img_request);	/* TEMPORARY */

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