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btrfs: extend locked section when adding a new device in device_list_add

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Make sure the device_list_lock is held the whole time:

* when the device is being looked up
* new device is initialized and put to the list
* the list counters are updated (fs_devices::opened, fs_devices::total_devices)

Signed-off-by: Anand Jain <anand.jain@oracle.com>
[ update changelog ]
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
This commit is contained in:
Anand Jain 2018-05-29 14:10:20 +08:00 committed by David Sterba
parent 4306a97449
commit 9c6d173ea6
1 changed files with 12 additions and 4 deletions
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16
fs/btrfs/volumes.c
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@ -762,21 +762,26 @@ 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;
}
@ -784,14 +789,13 @@ 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;
@ -838,12 +842,15 @@ 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)) {
@ -863,6 +870,7 @@ 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;
}