From 5679c59f608f2fedff313e59b374257f1c945234 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Mon, 11 Feb 2013 12:33:24 -0600 Subject: [PATCH] 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: Alex Elder Reviewed-by: Josh Durgin --- drivers/block/rbd.c | 37 +++++++++++++++++++++++++++++++++++++ 1 file changed, 37 insertions(+) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 211baa7f4f0b..b1b8ef864d58 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 */ -- 2.30.2