@@ -2429,21 +2429,15 @@ struct btrfs_device *btrfs_find_device_by_devspec(
return device;
}
-/*
- * does all the dirty work required for changing file system's UUID.
- */
-static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
+static struct btrfs_fs_devices *btrfs_init_sprout(struct btrfs_fs_info *fs_info)
{
struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
struct btrfs_fs_devices *old_devices;
struct btrfs_fs_devices *seed_devices;
- struct btrfs_super_block *disk_super = fs_info->super_copy;
- struct btrfs_device *device;
- u64 super_flags;
lockdep_assert_held(&uuid_mutex);
if (!fs_devices->seeding)
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
/*
* Private copy of the seed devices, anchored at
@@ -2451,7 +2445,7 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
*/
seed_devices = alloc_fs_devices(NULL, NULL);
if (IS_ERR(seed_devices))
- return PTR_ERR(seed_devices);
+ return seed_devices;
/*
* It's necessary to retain a copy of the original seed fs_devices in
@@ -2462,7 +2456,7 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
old_devices = clone_fs_devices(fs_devices);
if (IS_ERR(old_devices)) {
kfree(seed_devices);
- return PTR_ERR(old_devices);
+ return old_devices;
}
list_add(&old_devices->fs_list, &fs_uuids);
@@ -2473,7 +2467,41 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
INIT_LIST_HEAD(&seed_devices->alloc_list);
mutex_init(&seed_devices->device_list_mutex);
- mutex_lock(&fs_devices->device_list_mutex);
+ return seed_devices;
+}
+
+/*
+ * Splice seed devices into the sprout fs_devices.
+ * Generate a new fsid for the sprouted readwrite btrfs.
+ */
+static void btrfs_setup_sprout(struct btrfs_fs_info *fs_info,
+ struct btrfs_fs_devices *seed_devices)
+{
+ struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+ struct btrfs_super_block *disk_super = fs_info->super_copy;
+ struct btrfs_device *device;
+ u64 super_flags;
+
+ /*
+ * We are updating the fsid, the thread leading to device_list_add()
+ * could race, so uuid_mutex is needed.
+ */
+ lockdep_assert_held(&uuid_mutex);
+
+ /*
+ * Below threads though they parse dev_list they are fine without
+ * device_list_mutex:
+ * All device ops and balance - as we are in btrfs_exclop_start.
+ * Various dev_list read parser - are using rcu.
+ * btrfs_ioctl_fitrim() - is using rcu.
+ *
+ * For-read threads as below are using device_list_mutex:
+ * Readonly scrub btrfs_scrub_dev()
+ * Readonly scrub btrfs_scrub_progress()
+ * btrfs_get_dev_stats()
+ */
+ lockdep_assert_held(&fs_devices->device_list_mutex);
+
list_splice_init_rcu(&fs_devices->devices, &seed_devices->devices,
synchronize_rcu);
list_for_each_entry(device, &seed_devices->devices, dev_list)
@@ -2489,13 +2517,10 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
generate_random_uuid(fs_devices->fsid);
memcpy(fs_devices->metadata_uuid, fs_devices->fsid, BTRFS_FSID_SIZE);
memcpy(disk_super->fsid, fs_devices->fsid, BTRFS_FSID_SIZE);
- mutex_unlock(&fs_devices->device_list_mutex);
super_flags = btrfs_super_flags(disk_super) &
~BTRFS_SUPER_FLAG_SEEDING;
btrfs_set_super_flags(disk_super, super_flags);
-
- return 0;
}
/*
@@ -2586,6 +2611,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
struct super_block *sb = fs_info->sb;
struct rcu_string *name;
struct btrfs_fs_devices *fs_devices = fs_info->fs_devices;
+ struct btrfs_fs_devices *seed_devices;
u64 orig_super_total_bytes;
u64 orig_super_num_devices;
int ret = 0;
@@ -2669,18 +2695,26 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
if (seeding_dev) {
btrfs_clear_sb_rdonly(sb);
- ret = btrfs_prepare_sprout(fs_info);
- if (ret) {
+
+ /* GFP_KERNEL alloc should not be under device_list_mutex */
+ seed_devices = btrfs_init_sprout(fs_info);
+ if (IS_ERR(seed_devices)) {
+ ret = PTR_ERR(seed_devices);
btrfs_abort_transaction(trans, ret);
goto error_trans;
}
+ }
+
+ mutex_lock(&fs_devices->device_list_mutex);
+ if (seeding_dev) {
+ btrfs_setup_sprout(fs_info, seed_devices);
+
btrfs_assign_next_active_device(fs_info->fs_devices->latest_dev,
device);
}
device->fs_devices = fs_devices;
- mutex_lock(&fs_devices->device_list_mutex);
mutex_lock(&fs_info->chunk_mutex);
list_add_rcu(&device->dev_list, &fs_devices->devices);
list_add(&device->dev_alloc_list, &fs_devices->alloc_list);
@@ -2742,7 +2776,7 @@ int btrfs_init_new_device(struct btrfs_fs_info *fs_info, const char *device_path
/*
* fs_devices now represents the newly sprouted filesystem and
- * its fsid has been changed by btrfs_prepare_sprout
+ * its fsid has been changed by btrfs_sprout_splice().
*/
btrfs_sysfs_update_sprout_fsid(fs_devices);
}