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Commit 6d292906 authored by Alex Elder's avatar Alex Elder Committed by Sage Weil
Browse files

rbd: define flags field, use it for exists flag 



Define a new rbd device flags field, manipulated using bit
operations.  Replace the use of the current "exists" flag with a bit
in this new "flags" field.  Add a little commentary about the
"exists" flag, which does not need to be manipulated atomically.

Signed-off-by: default avatarAlex Elder <elder@inktank.com>
Reviewed-by: default avatarJosh Durgin <josh.durgin@inktank.com>
parent 8eb87565

drivers/block/rbd.c

+28 −9
Original line number Diff line number Diff line
@@ -264,7 +264,7 @@ struct rbd_device { 
	spinlock_t		lock;		/* queue lock */



	struct rbd_image_header	header;

	atomic_t		exists;

	unsigned long		flags;

	struct rbd_spec		*spec;



	char			*header_name;
@@ -292,6 +292,12 @@ struct rbd_device { 
	unsigned long		open_count;

};



/* Flag bits for rbd_dev->flags */



enum rbd_dev_flags {

	RBD_DEV_FLAG_EXISTS,	/* mapped snapshot has not been deleted */

};



static DEFINE_MUTEX(ctl_mutex);	  /* Serialize open/close/setup/teardown */



static LIST_HEAD(rbd_dev_list);    /* devices */
@@ -782,7 +788,8 @@ static int rbd_dev_set_mapping(struct rbd_device *rbd_dev) 
			goto done;

		rbd_dev->mapping.read_only = true;

	}

	atomic_set(&rbd_dev->exists, 1);

	set_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);



done:

	return ret;

}
@@ -1877,9 +1884,14 @@ static void rbd_request_fn(struct request_queue *q) 
			rbd_assert(rbd_dev->spec->snap_id == CEPH_NOSNAP);

		}



		/* Quit early if the snapshot has disappeared */



		if (!atomic_read(&rbd_dev->exists)) {

		/*

		 * Quit early if the mapped snapshot no longer

		 * exists.  It's still possible the snapshot will

		 * have disappeared by the time our request arrives

		 * at the osd, but there's no sense in sending it if

		 * we already know.

		 */

		if (!test_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags)) {

			dout("request for non-existent snapshot");

			rbd_assert(rbd_dev->spec->snap_id != CEPH_NOSNAP);

			result = -ENXIO;
@@ -2571,7 +2583,7 @@ struct rbd_device *rbd_dev_create(struct rbd_client *rbdc, 
		return NULL;



	spin_lock_init(&rbd_dev->lock);

	atomic_set(&rbd_dev->exists, 0);

	rbd_dev->flags = 0;

	INIT_LIST_HEAD(&rbd_dev->node);

	INIT_LIST_HEAD(&rbd_dev->snaps);

	init_rwsem(&rbd_dev->header_rwsem);
@@ -3200,10 +3212,17 @@ static int rbd_dev_snaps_update(struct rbd_device *rbd_dev) 
		if (snap_id == CEPH_NOSNAP || (snap && snap->id > snap_id)) {

			struct list_head *next = links->next;



			/* Existing snapshot not in the new snap context */



			/*

			 * A previously-existing snapshot is not in

			 * the new snap context.

			 *

			 * If the now missing snapshot is the one the

			 * image is mapped to, clear its exists flag

			 * so we can avoid sending any more requests

			 * to it.

			 */

			if (rbd_dev->spec->snap_id == snap->id)

				atomic_set(&rbd_dev->exists, 0);

				clear_bit(RBD_DEV_FLAG_EXISTS, &rbd_dev->flags);

			rbd_remove_snap_dev(snap);

			dout("%ssnap id %llu has been removed\n",

				rbd_dev->spec->snap_id == snap->id ?