When the device is added or if the device pointer is retrieved
for writing, make sure that device_list_mutex is held. Also
make sure it is held when we check fs_devices::opened and
fs_devices::total_devices is updated.
Signed-off-by: Anand Jain <anand.j...@oracle.com>
---
fs/btrfs/volumes.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 4edba7c5c050..0fdb9b717398 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -765,21 +765,26 @@ static noinline struct btrfs_device
*device_list_add(const char *path,
if (IS_ERR(fs_devices))
return ERR_CAST(fs_devices);
+ mutex_lock(&fs_devices->device_list_mutex);
list_add(&fs_devices->fs_list, &fs_uuids);
device = NULL;
} else {
+ mutex_lock(&fs_devices->device_list_mutex);
device = find_device(fs_devices, devid,
disk_super->dev_item.uuid);
}
if (!device) {
- if (fs_devices->opened)
+ if (fs_devices->opened) {
+ mutex_unlock(&fs_devices->device_list_mutex);
return ERR_PTR(-EBUSY);
+ }
device = btrfs_alloc_device(NULL, &devid,
disk_super->dev_item.uuid);
if (IS_ERR(device)) {
+ mutex_unlock(&fs_devices->device_list_mutex);
/* we can safely leave the fs_devices entry around */
return device;
}
@@ -787,14 +792,13 @@ static noinline struct btrfs_device
*device_list_add(const char *path,
name = rcu_string_strdup(path, GFP_NOFS);
if (!name) {
btrfs_free_device(device);
+ mutex_unlock(&fs_devices->device_list_mutex);
return ERR_PTR(-ENOMEM);
}
rcu_assign_pointer(device->name, name);
- mutex_lock(&fs_devices->device_list_mutex);
list_add_rcu(&device->dev_list, &fs_devices->devices);
fs_devices->num_devices++;
- mutex_unlock(&fs_devices->device_list_mutex);
device->fs_devices = fs_devices;
*new_device_added = true;
@@ -841,12 +845,15 @@ static noinline struct btrfs_device
*device_list_add(const char *path,
* with larger generation number or the last-in if
* generation are equal.
*/
+ mutex_unlock(&fs_devices->device_list_mutex);
return ERR_PTR(-EEXIST);
}
name = rcu_string_strdup(path, GFP_NOFS);
- if (!name)
+ if (!name) {
+ mutex_unlock(&fs_devices->device_list_mutex);
return ERR_PTR(-ENOMEM);
+ }
rcu_string_free(device->name);
rcu_assign_pointer(device->name, name);
if (test_bit(BTRFS_DEV_STATE_MISSING, &device->dev_state)) {
@@ -866,6 +873,7 @@ static noinline struct btrfs_device *device_list_add(const
char *path,
fs_devices->total_devices = btrfs_super_num_devices(disk_super);
+ mutex_unlock(&fs_devices->device_list_mutex);
return device;
}
--
2.7.0
--
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