The rbd_device->exists field can be updated asynchronously, changing
from set to clear if a mapped snapshot disappears from the base
image's snapshot context.
Currently, value of the "exists" flag is only read and modified
under protection of the header semaphore, but that will change with
the next patch. Making it atomic ensures this won't be a problem
because the a the non-existence of device will be immediately known.
Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
spinlock_t lock; /* queue lock */
struct rbd_image_header header;
spinlock_t lock; /* queue lock */
struct rbd_image_header header;
struct rbd_spec *spec;
char *header_name;
struct rbd_spec *spec;
char *header_name;
goto done;
rbd_dev->mapping.read_only = true;
}
goto done;
rbd_dev->mapping.read_only = true;
}
- rbd_dev->exists = true;
+ atomic_set(&rbd_dev->exists, 1);
/* Grab a reference to the snapshot context */
down_read(&rbd_dev->header_rwsem);
/* Grab a reference to the snapshot context */
down_read(&rbd_dev->header_rwsem);
+ if (atomic_read(&rbd_dev->exists)) {
snapc = ceph_get_snap_context(rbd_dev->header.snapc);
rbd_assert(snapc != NULL);
}
snapc = ceph_get_snap_context(rbd_dev->header.snapc);
rbd_assert(snapc != NULL);
}
return NULL;
spin_lock_init(&rbd_dev->lock);
return NULL;
spin_lock_init(&rbd_dev->lock);
+ atomic_set(&rbd_dev->exists, 0);
INIT_LIST_HEAD(&rbd_dev->node);
INIT_LIST_HEAD(&rbd_dev->snaps);
init_rwsem(&rbd_dev->header_rwsem);
INIT_LIST_HEAD(&rbd_dev->node);
INIT_LIST_HEAD(&rbd_dev->snaps);
init_rwsem(&rbd_dev->header_rwsem);
/* Existing snapshot not in the new snap context */
if (rbd_dev->spec->snap_id == snap->id)
/* Existing snapshot not in the new snap context */
if (rbd_dev->spec->snap_id == snap->id)
- rbd_dev->exists = false;
+ atomic_set(&rbd_dev->exists, 0);
rbd_remove_snap_dev(snap);
dout("%ssnap id %llu has been removed\n",
rbd_dev->spec->snap_id == snap->id ?
rbd_remove_snap_dev(snap);
dout("%ssnap id %llu has been removed\n",
rbd_dev->spec->snap_id == snap->id ?