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authorAlex Elder <elder@inktank.com>2013-01-14 12:43:31 -0600
committerSage Weil <sage@inktank.com>2013-02-13 18:29:10 -0800
commit6d292906f80170f4647079dd503df18b737750af (patch)
tree2fc2b4f1235375cd143ab261540ce19e56d8ab62 /drivers/block
parent8eb87565306cf40a32f5d0883d008675cd2dd510 (diff)
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: Alex Elder <elder@inktank.com> Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
Diffstat (limited to 'drivers/block')
-rw-r--r--drivers/block/rbd.c37
1 files changed, 28 insertions, 9 deletions
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index fd9656b5fdb..8c90a39c2a9 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -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 ?