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rbd: protect the rbd_dev_list with a spinlock 

The rbd_dev_list is just a simple list of all the current
rbd_devices.  Using the ctl_mutex as a concurrency guard is
overkill.  Instead, use a spinlock for that specific purpose.

This also reduces the window that the ctl_mutex needs to be held in
rbd_add().

Signed-off-by: Alex Elder <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>
This commit is contained in:
Alex Elder 2012-01-29 13:57:44 -06:00
parent 1ddbe94eda
commit e124a82f3c
1 changed files with 22 additions and 11 deletions
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33
drivers/block/rbd.c
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@ -174,11 +174,13 @@ static struct bus_type rbd_bus_type = {
.name = "rbd",
};
static DEFINE_SPINLOCK(node_lock); /* protects client get/put */
static DEFINE_MUTEX(ctl_mutex); /* Serialize open/close/setup/teardown */
static LIST_HEAD(rbd_dev_list); /* devices */
static DEFINE_SPINLOCK(rbd_dev_list_lock);
static LIST_HEAD(rbd_client_list); /* clients */
static DEFINE_SPINLOCK(node_lock); /* protects client get/put */
static int __rbd_init_snaps_header(struct rbd_device *rbd_dev);
static void rbd_dev_release(struct device *dev);
@ -2209,12 +2211,12 @@ 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 */
mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
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);
/* parse add command */
if (sscanf(buf, "%" __stringify(RBD_MAX_OPT_LEN) "s "
@ -2238,12 +2240,14 @@ static ssize_t rbd_add(struct bus_type *bus,
/* initialize rest of new object */
snprintf(rbd_dev->name, DEV_NAME_LEN, DRV_NAME "%d", rbd_dev->id);
mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
rc = rbd_get_client(rbd_dev, mon_dev_name, options);
mutex_unlock(&ctl_mutex);
if (rc < 0)
goto err_out_slot;
mutex_unlock(&ctl_mutex);
/* pick the pool */
osdc = &rbd_dev->rbd_client->client->osdc;
rc = ceph_pg_poolid_by_name(osdc->osdmap, rbd_dev->pool_name);
@ -2275,9 +2279,9 @@ static ssize_t rbd_add(struct bus_type *bus,
return count;
err_out_bus:
mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
spin_lock(&rbd_dev_list_lock);
list_del_init(&rbd_dev->node);
mutex_unlock(&ctl_mutex);
spin_unlock(&rbd_dev_list_lock);
rbd_id_put(target_id);
/* this will also clean up rest of rbd_dev stuff */
@ -2291,10 +2295,10 @@ err_out_blkdev:
unregister_blkdev(rbd_dev->major, rbd_dev->name);
err_out_client:
rbd_put_client(rbd_dev);
mutex_lock_nested(&ctl_mutex, SINGLE_DEPTH_NESTING);
err_out_slot:
spin_lock(&rbd_dev_list_lock);
list_del_init(&rbd_dev->node);
mutex_unlock(&ctl_mutex);
spin_unlock(&rbd_dev_list_lock);
rbd_id_put(target_id);
kfree(rbd_dev);
@ -2313,11 +2317,15 @@ static struct rbd_device *__rbd_get_dev(unsigned long id)
struct list_head *tmp;
struct rbd_device *rbd_dev;
spin_lock(&rbd_dev_list_lock);
list_for_each(tmp, &rbd_dev_list) {
rbd_dev = list_entry(tmp, struct rbd_device, node);
if (rbd_dev->id == id)
if (rbd_dev->id == id) {
spin_unlock(&rbd_dev_list_lock);
return rbd_dev;
}
}
spin_unlock(&rbd_dev_list_lock);
return NULL;
}
@ -2372,7 +2380,10 @@ 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_remove_all_snaps(rbd_dev);