btrfs: document some invariants of seed code (427c8fdd) · Commits · 戴 / test

fs/btrfs/volumes.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -2357,10 +2357,20 @@ static int btrfs_prepare_sprout(struct btrfs_fs_info *fs_info)
		if (!fs_devices->seeding)
		return -EINVAL;

		/*
		* Private copy of the seed devices, anchored at
		* fs_info->fs_devices->seed_list
		*/
		seed_devices = alloc_fs_devices(NULL, NULL);
		if (IS_ERR(seed_devices))
		return PTR_ERR(seed_devices);

		/*
		* It's necessary to retain a copy of the original seed fs_devices in
		* fs_uuids so that filesystems which have been seeded can successfully
		* reference the seed device from open_seed_devices. This also supports
		* multiple fs seed.
		*/
		old_devices = clone_fs_devices(fs_devices);
		if (IS_ERR(old_devices)) {
		kfree(seed_devices);
		@@ -6720,6 +6730,7 @@ static struct btrfs_fs_devices open_seed_devices(struct btrfs_fs_info fs_info,
		lockdep_assert_held(&uuid_mutex);
		ASSERT(fsid);

		/* This will match only for multi-device seed fs */
		list_for_each_entry(fs_devices, &fs_info->fs_devices->seed_list, seed_list)
		if (!memcmp(fs_devices->fsid, fsid, BTRFS_FSID_SIZE))
		return fs_devices;
		@@ -6739,6 +6750,10 @@ static struct btrfs_fs_devices open_seed_devices(struct btrfs_fs_info fs_info,
		return fs_devices;
		}

		/*
		* Upon first call for a seed fs fsid, just create a private copy of the
		* respective fs_devices and anchor it at fs_info->fs_devices->seed_list
		*/
		fs_devices = clone_fs_devices(fs_devices);
		if (IS_ERR(fs_devices))
		return fs_devices;