Commit c9513edb authored by Xiao Guangrong's avatar Xiao Guangrong Committed by Chris Mason

Btrfs: fix the race between reading and updating devices

On btrfs_congested_fn and __unplug_io_fn paths, we should hold
device_list_mutex to avoid remove/add device path to
update fs_devices->devices

On __btrfs_close_devices and btrfs_prepare_sprout paths, the devices in
fs_devices->devices or fs_devices->devices is updated, so we should hold
the mutex to avoid the reader side to reach them
Signed-off-by: default avatarXiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Signed-off-by: default avatarChris Mason <chris.mason@oracle.com>
parent 4f6c9328
......@@ -1410,6 +1410,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits)
struct btrfs_device *device;
struct backing_dev_info *bdi;
mutex_lock(&info->fs_devices->device_list_mutex);
list_for_each_entry(device, &info->fs_devices->devices, dev_list) {
if (!device->bdev)
continue;
......@@ -1419,6 +1420,7 @@ static int btrfs_congested_fn(void *congested_data, int bdi_bits)
break;
}
}
mutex_unlock(&info->fs_devices->device_list_mutex);
return ret;
}
......
......@@ -481,6 +481,7 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
if (--fs_devices->opened > 0)
return 0;
mutex_lock(&fs_devices->device_list_mutex);
list_for_each_entry(device, &fs_devices->devices, dev_list) {
if (device->bdev) {
blkdev_put(device->bdev, device->mode);
......@@ -495,6 +496,8 @@ static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices)
device->writeable = 0;
device->in_fs_metadata = 0;
}
mutex_unlock(&fs_devices->device_list_mutex);
WARN_ON(fs_devices->open_devices);
WARN_ON(fs_devices->rw_devices);
fs_devices->opened = 0;
......@@ -1415,7 +1418,11 @@ static int btrfs_prepare_sprout(struct btrfs_trans_handle *trans,
INIT_LIST_HEAD(&seed_devices->devices);
INIT_LIST_HEAD(&seed_devices->alloc_list);
mutex_init(&seed_devices->device_list_mutex);
mutex_lock(&root->fs_info->fs_devices->device_list_mutex);
list_splice_init(&fs_devices->devices, &seed_devices->devices);
mutex_unlock(&root->fs_info->fs_devices->device_list_mutex);
list_splice_init(&fs_devices->alloc_list, &seed_devices->alloc_list);
list_for_each_entry(device, &seed_devices->devices, dev_list) {
device->fs_devices = seed_devices;
......
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