From e124a82f3c4efc2cc2bae68a2bf30020fb8c4fc2 Mon Sep 17 00:00:00 2001 From: Alex Elder Date: Sun, 29 Jan 2012 13:57:44 -0600 Subject: [PATCH] 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 Signed-off-by: Sage Weil --- drivers/block/rbd.c | 33 ++++++++++++++++++++++----------- 1 file changed, 22 insertions(+), 11 deletions(-) diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c index 62da8ccc5fcb..e259feedc7d0 100644 --- a/drivers/block/rbd.c +++ b/drivers/block/rbd.c @@ -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); -- 2.30.2