Commit 47e6f742 authored by David Sterba's avatar David Sterba
Browse files

btrfs: add support for 3-copy replication (raid1c3) 



Add new block group profile to store 3 copies in a simliar way that
current RAID1 does. The profile attributes and constraints are defined
in the raid table and used by the same code that already handles the
2-copy RAID1.

The minimum number of devices is 3, the maximum number of devices/chunks
that can be lost/damaged is 2. Like RAID6 but with 33% space
utilization.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent fac07d2b

fs/btrfs/ctree.h

+2 −2
Original line number Diff line number Diff line
@@ -57,9 +57,9 @@ struct btrfs_ref; 
 * filesystem data as well that can be used to read data in order to repair

 * read errors on other disks.

 *

 * Current value is derived from RAID1 with 2 copies.

 * Current value is derived from RAID1C3 with 3 copies.

 */

#define BTRFS_MAX_MIRRORS (2 + 1)

#define BTRFS_MAX_MIRRORS (3 + 1)



#define BTRFS_MAX_LEVEL 8

fs/btrfs/super.c

+2 −0
Original line number Diff line number Diff line
@@ -1935,6 +1935,8 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info, 
		num_stripes = nr_devices;

	else if (type & BTRFS_BLOCK_GROUP_RAID1)

		num_stripes = 2;

	else if (type & BTRFS_BLOCK_GROUP_RAID1C3)

		num_stripes = 3;

	else if (type & BTRFS_BLOCK_GROUP_RAID10)

		num_stripes = 4;

fs/btrfs/volumes.c

+17 −2
Original line number Diff line number Diff line
@@ -58,6 +58,18 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = { 
		.bg_flag	= BTRFS_BLOCK_GROUP_RAID1,

		.mindev_error	= BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET,

	},

	[BTRFS_RAID_RAID1C3] = {

		.sub_stripes	= 1,

		.dev_stripes	= 1,

		.devs_max	= 0,

		.devs_min	= 3,

		.tolerated_failures = 2,

		.devs_increment	= 3,

		.ncopies	= 3,

		.raid_name	= "raid1c3",

		.bg_flag	= BTRFS_BLOCK_GROUP_RAID1C3,

		.mindev_error	= BTRFS_ERROR_DEV_RAID1C3_MIN_NOT_MET,

	},

	[BTRFS_RAID_DUP] = {

		.sub_stripes	= 1,

		.dev_stripes	= 2,
@@ -4839,8 +4851,11 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans, 
	sort(devices_info, ndevs, sizeof(struct btrfs_device_info),

	     btrfs_cmp_device_info, NULL);



	/* round down to number of usable stripes */

	ndevs = round_down(ndevs, devs_increment);

	/*

	 * Round down to number of usable stripes, devs_increment can be any

	 * number so we can't use round_down()

	 */

	ndevs -= ndevs % devs_increment;



	if (ndevs < devs_min) {

		ret = -ENOSPC;

fs/btrfs/volumes.h

+2 −0
Original line number Diff line number Diff line
@@ -545,6 +545,8 @@ static inline enum btrfs_raid_types btrfs_bg_flags_to_raid_index(u64 flags) 
		return BTRFS_RAID_RAID10;

	else if (flags & BTRFS_BLOCK_GROUP_RAID1)

		return BTRFS_RAID_RAID1;

	else if (flags & BTRFS_BLOCK_GROUP_RAID1C3)

		return BTRFS_RAID_RAID1C3;

	else if (flags & BTRFS_BLOCK_GROUP_DUP)

		return BTRFS_RAID_DUP;

	else if (flags & BTRFS_BLOCK_GROUP_RAID0)

include/uapi/linux/btrfs.h

+2 −1
Original line number Diff line number Diff line
@@ -831,7 +831,8 @@ enum btrfs_err_code { 
	BTRFS_ERROR_DEV_TGT_REPLACE,

	BTRFS_ERROR_DEV_MISSING_NOT_FOUND,

	BTRFS_ERROR_DEV_ONLY_WRITABLE,

	BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS

	BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS,

	BTRFS_ERROR_DEV_RAID1C3_MIN_NOT_MET,

};



#define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \

CRA Git | Maintained and supported by SUSTech CRA and CCSE