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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 <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Alex Elder 2012-02-02 08:13:29 -06:00
parent e124a82f3c
commit 499afd5b8e
1 changed files with 21 additions and 26 deletions
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47
drivers/block/rbd.c
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@ -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);