Commit d1a63002 authored by Nikolay Borisov's avatar Nikolay Borisov Committed by David Sterba
Browse files

btrfs: add members to fs_devices to track fsid changes 



In order to gracefully handle split-brain scenario during fsid change
(which are very unlikely, yet possible), two more pieces of information
will be necessary:

1. The highest generation number among all devices registered to a
   particular btrfs_fs_devices

2. A boolean flag whether a given btrfs_fs_devices was created by a
   device which had the FSID_CHANGING_V2 flag set.

This is a preparatory patch and just introduces the variables as well
as code which sets them, their actual use is going to happen in a later
patch.

Signed-off-by: default avatarNikolay Borisov <nborisov@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent fbc6feae

fs/btrfs/volumes.c

+8 −1
Original line number Original line Diff line number Diff line
@@ -792,6 +792,8 @@ static noinline struct btrfs_device *device_list_add(const char *path, 
	u64 devid = btrfs_stack_device_id(&disk_super->dev_item);

	u64 devid = btrfs_stack_device_id(&disk_super->dev_item);

	bool has_metadata_uuid = (btrfs_super_incompat_flags(disk_super) &

	bool has_metadata_uuid = (btrfs_super_incompat_flags(disk_super) &

		BTRFS_FEATURE_INCOMPAT_METADATA_UUID);

		BTRFS_FEATURE_INCOMPAT_METADATA_UUID);

	bool fsid_change_in_progress = (btrfs_super_flags(disk_super) &

					BTRFS_SUPER_FLAG_CHANGING_FSID_V2);





	if (has_metadata_uuid)

	if (has_metadata_uuid)

		fs_devices = find_fsid(disk_super->fsid, disk_super->metadata_uuid);

		fs_devices = find_fsid(disk_super->fsid, disk_super->metadata_uuid);
@@ -805,6 +807,8 @@ static noinline struct btrfs_device *device_list_add(const char *path, 
		else

		else

			fs_devices = alloc_fs_devices(disk_super->fsid, NULL);

			fs_devices = alloc_fs_devices(disk_super->fsid, NULL);





		fs_devices->fsid_change = fsid_change_in_progress;



		if (IS_ERR(fs_devices))

		if (IS_ERR(fs_devices))

			return ERR_CAST(fs_devices);

			return ERR_CAST(fs_devices);
@@ -940,8 +944,11 @@ static noinline struct btrfs_device *device_list_add(const char *path, 
	 * it back. We need it to pick the disk with largest generation

	 * it back. We need it to pick the disk with largest generation

	 * (as above).

	 * (as above).

	 */

	 */

	if (!fs_devices->opened)

	if (!fs_devices->opened) {

		device->generation = found_transid;

		device->generation = found_transid;

		fs_devices->latest_generation = max_t(u64, found_transid,

						fs_devices->latest_generation);

	}





	fs_devices->total_devices = btrfs_super_num_devices(disk_super);

	fs_devices->total_devices = btrfs_super_num_devices(disk_super);

fs/btrfs/volumes.h

+5 −0
Original line number Original line Diff line number Diff line
@@ -211,6 +211,7 @@ BTRFS_DEVICE_GETSET_FUNCS(bytes_used); 
struct btrfs_fs_devices {

struct btrfs_fs_devices {

	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */

	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */

	u8 metadata_uuid[BTRFS_FSID_SIZE];

	u8 metadata_uuid[BTRFS_FSID_SIZE];

	bool fsid_change;

	struct list_head fs_list;

	struct list_head fs_list;





	u64 num_devices;

	u64 num_devices;
@@ -219,6 +220,10 @@ struct btrfs_fs_devices { 
	u64 missing_devices;

	u64 missing_devices;

	u64 total_rw_bytes;

	u64 total_rw_bytes;

	u64 total_devices;

	u64 total_devices;



	/* Highest generation number of seen devices */

	u64 latest_generation;



	struct block_device *latest_bdev;

	struct block_device *latest_bdev;





	/* all of the devices in the FS, protected by a mutex

	/* all of the devices in the FS, protected by a mutex

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