From e124a82f3c4efc2cc2bae68a2bf30020fb8c4fc2 Mon Sep 17 00:00:00 2001
From: Alex Elder <elder@dreamhost.com>
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 <elder@dreamhost.com>
Signed-off-by: Sage Weil <sage@newdream.net>
---
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 @@ static ssize_t rbd_add(struct bus_type *bus,
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);
--
GitLab