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 (no 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: Alex Elder <[email protected]>
---
drivers/block/rbd.c | 37 +++++++++++++++++++++++++++++++++++++
1 file changed, 37 insertions(+)
diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 211baa7f..b1b8ef8 100644
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -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 */
--
1.7.9.5
--
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