From 499afd5b8e742792fda6bd7730c738ad83aecf6b Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Thu, 2 Feb 2012 08:13:29 -0600 Subject: [PATCH] rbd: tie rbd_dev_list changes to rbd_id operations The only time entries are added to or removed from the global rbd_dev_list is exactly when a "put" or "get" operation is being performed on a rbd_dev's id. So just move the list management code into get/put routines. Signed-off-by: Alex Elder Signed-off-by: Sage Weil --- drivers/block/rbd.c | 47 +++++++++++++++++++++-------------------------- 1 file changed, 21 insertions(+), 26 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index e259fee..e7727e8 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -2154,26 +2154,36 @@ static int rbd_init_watch_dev(struct rbd_device *rbd_dev) static atomic64_t rbd_id_max = ATOMIC64_INIT(0); /* - * Get a unique rbd identifier. The minimum rbd id is 1. + * Get a unique rbd identifier for the given new rbd_dev, and add + * the rbd_dev to the global list. The minimum rbd id is 1. */ -static int rbd_id_get(void) +static void rbd_id_get(struct rbd_device *rbd_dev) { - return atomic64_inc_return(&rbd_id_max); + rbd_dev->id = atomic64_inc_return(&rbd_id_max); + + spin_lock(&rbd_dev_list_lock); + list_add_tail(&rbd_dev->node, &rbd_dev_list); + spin_unlock(&rbd_dev_list_lock); } /* - * Record that an rbd identifier is no longer in use. + * Remove an rbd_dev from the global list, and record that its + * identifier is no longer in use. */ -static void rbd_id_put(int rbd_id) +static void rbd_id_put(struct rbd_device *rbd_dev) { - BUG_ON(rbd_id < 1); + BUG_ON(rbd_dev->id < 1); + + spin_lock(&rbd_dev_list_lock); + list_del_init(&rbd_dev->node); + spin_unlock(&rbd_dev_list_lock); /* * New id's are always one more than the current maximum. * If the id being "put" *is* that maximum, decrement the * maximum so the next one requested just reuses this one. */ - atomic64_cmpxchg(&rbd_id_max, rbd_id, rbd_id - 1); + atomic64_cmpxchg(&rbd_id_max, rbd_dev->id, rbd_dev->id - 1); } static ssize_t rbd_add(struct bus_type *bus, @@ -2211,12 +2221,7 @@ static ssize_t rbd_add(struct bus_type *bus, init_rwsem(&rbd_dev->header.snap_rwsem); /* generate unique id: one more than highest used so far */ - rbd_dev->id = rbd_id_get(); - - /* add to global list */ - spin_lock(&rbd_dev_list_lock); - list_add_tail(&rbd_dev->node, &rbd_dev_list); - spin_unlock(&rbd_dev_list_lock); + rbd_id_get(rbd_dev); /* parse add command */ if (sscanf(buf, "%" __stringify(RBD_MAX_OPT_LEN) "s " @@ -2279,10 +2284,7 @@ static ssize_t rbd_add(struct bus_type *bus, return count; err_out_bus: - spin_lock(&rbd_dev_list_lock); - list_del_init(&rbd_dev->node); - spin_unlock(&rbd_dev_list_lock); - rbd_id_put(target_id); + rbd_id_put(rbd_dev); /* this will also clean up rest of rbd_dev stuff */ @@ -2296,10 +2298,7 @@ err_out_blkdev: err_out_client: rbd_put_client(rbd_dev); err_out_slot: - spin_lock(&rbd_dev_list_lock); - list_del_init(&rbd_dev->node); - spin_unlock(&rbd_dev_list_lock); - rbd_id_put(target_id); + rbd_id_put(rbd_dev); kfree(rbd_dev); err_out_opt: @@ -2380,11 +2379,7 @@ static ssize_t rbd_remove(struct bus_type *bus, goto done; } - spin_lock(&rbd_dev_list_lock); - list_del_init(&rbd_dev->node); - spin_unlock(&rbd_dev_list_lock); - - rbd_id_put(target_id); + rbd_id_put(rbd_dev); __rbd_remove_all_snaps(rbd_dev); rbd_bus_del_dev(rbd_dev); -- 2.7.4