* device_list_mutex
* chunk_mutex
* balance_mutex
+ *
+ *
+ * Exclusive operations, BTRFS_FS_EXCL_OP
+ * ======================================
+ *
+ * Maintains the exclusivity of the following operations that apply to the
+ * whole filesystem and cannot run in parallel.
+ *
+ * - Balance (*)
+ * - Device add
+ * - Device remove
+ * - Device replace (*)
+ * - Resize
+ *
+ * The device operations (as above) can be in one of the following states:
+ *
+ * - Running state
+ * - Paused state
+ * - Completed state
+ *
+ * Only device operations marked with (*) can go into the Paused state for the
+ * following reasons:
+ *
+ * - ioctl (only Balance can be Paused through ioctl)
+ * - filesystem remounted as read-only
+ * - filesystem unmounted and mounted as read-only
+ * - system power-cycle and filesystem mounted as read-only
+ * - filesystem or device errors leading to forced read-only
+ *
+ * BTRFS_FS_EXCL_OP flag is set and cleared using atomic operations.
+ * During the course of Paused state, the BTRFS_FS_EXCL_OP remains set.
+ * A device operation in Paused or Running state can be canceled or resumed
+ * either by ioctl (Balance only) or when remounted as read-write.
+ * BTRFS_FS_EXCL_OP flag is cleared when the device operation is canceled or
+ * completed.
*/
DEFINE_MUTEX(uuid_mutex);
INIT_LIST_HEAD(&fs_devs->devices);
INIT_LIST_HEAD(&fs_devs->resized_devices);
INIT_LIST_HEAD(&fs_devs->alloc_list);
- INIT_LIST_HEAD(&fs_devs->list);
+ INIT_LIST_HEAD(&fs_devs->fs_list);
if (fsid)
memcpy(fs_devs->fsid, fsid, BTRFS_FSID_SIZE);
while (!list_empty(&fs_uuids)) {
fs_devices = list_entry(fs_uuids.next,
- struct btrfs_fs_devices, list);
- list_del(&fs_devices->list);
+ struct btrfs_fs_devices, fs_list);
+ list_del(&fs_devices->fs_list);
free_fs_devices(fs_devices);
}
}
{
struct btrfs_fs_devices *fs_devices;
- list_for_each_entry(fs_devices, &fs_uuids, list) {
+ list_for_each_entry(fs_devices, &fs_uuids, fs_list) {
if (memcmp(fsid, fs_devices->fsid, BTRFS_FSID_SIZE) == 0)
return fs_devices;
}
struct btrfs_fs_devices *fs_devs, *tmp_fs_devs;
struct btrfs_device *dev, *tmp_dev;
- list_for_each_entry_safe(fs_devs, tmp_fs_devs, &fs_uuids, list) {
+ list_for_each_entry_safe(fs_devs, tmp_fs_devs, &fs_uuids, fs_list) {
if (fs_devs->opened)
continue;
/* delete the stale device */
if (fs_devs->num_devices == 1) {
btrfs_sysfs_remove_fsid(fs_devs);
- list_del(&fs_devs->list);
+ list_del(&fs_devs->fs_list);
free_fs_devices(fs_devs);
break;
} else {
if (IS_ERR(fs_devices))
return ERR_CAST(fs_devices);
- list_add(&fs_devices->list, &fs_uuids);
+ list_add(&fs_devices->fs_list, &fs_uuids);
device = NULL;
} else {
static int __btrfs_open_devices(struct btrfs_fs_devices *fs_devices,
fmode_t flags, void *holder)
{
- struct list_head *head = &fs_devices->devices;
struct btrfs_device *device;
struct btrfs_device *latest_dev = NULL;
int ret = 0;
flags |= FMODE_EXCL;
- list_for_each_entry(device, head, dev_list) {
+ list_for_each_entry(device, &fs_devices->devices, dev_list) {
/* Just open everything we can; ignore failures here */
if (btrfs_open_one_device(fs_devices, device, flags, holder))
continue;
return PTR_ERR(old_devices);
}
- list_add(&old_devices->list, &fs_uuids);
+ list_add(&old_devices->fs_list, &fs_uuids);
memcpy(seed_devices, fs_devices, sizeof(*seed_devices));
seed_devices->opened = 1;