Commit 8d6fac00 authored by David Sterba's avatar David Sterba
Browse files

btrfs: add support for 4-copy replication (raid1c4) 



Add new block group profile to store 4 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-
and 3-copy RAID1.

The minimum number of devices is 4, the maximum number of devices/chunks
that can be lost/damaged is 3. There is no comparable traditional RAID
level, the profile is added for future needs to accompany triple-parity
and beyond.

Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 47e6f742

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 RAID1C3 with 3 copies.

 * Current value is derived from RAID1C4 with 4 copies.

 */

#define BTRFS_MAX_MIRRORS (3 + 1)

#define BTRFS_MAX_MIRRORS (4 + 1)



#define BTRFS_MAX_LEVEL 8

fs/btrfs/super.c

+2 −0
Original line number Diff line number Diff line
@@ -1937,6 +1937,8 @@ static inline int btrfs_calc_avail_data_space(struct btrfs_fs_info *fs_info, 
		num_stripes = 2;

	else if (type & BTRFS_BLOCK_GROUP_RAID1C3)

		num_stripes = 3;

	else if (type & BTRFS_BLOCK_GROUP_RAID1C4)

		num_stripes = 4;

	else if (type & BTRFS_BLOCK_GROUP_RAID10)

		num_stripes = 4;

fs/btrfs/volumes.c

+12 −0
Original line number Diff line number Diff line
@@ -70,6 +70,18 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = { 
		.bg_flag	= BTRFS_BLOCK_GROUP_RAID1C3,

		.mindev_error	= BTRFS_ERROR_DEV_RAID1C3_MIN_NOT_MET,

	},

	[BTRFS_RAID_RAID1C4] = {

		.sub_stripes	= 1,

		.dev_stripes	= 1,

		.devs_max	= 0,

		.devs_min	= 4,

		.tolerated_failures = 3,

		.devs_increment	= 4,

		.ncopies	= 4,

		.raid_name	= "raid1c4",

		.bg_flag	= BTRFS_BLOCK_GROUP_RAID1C4,

		.mindev_error	= BTRFS_ERROR_DEV_RAID1C4_MIN_NOT_MET,

	},

	[BTRFS_RAID_DUP] = {

		.sub_stripes	= 1,

		.dev_stripes	= 2,

fs/btrfs/volumes.h

+2 −0
Original line number Diff line number Diff line
@@ -547,6 +547,8 @@ static inline enum btrfs_raid_types btrfs_bg_flags_to_raid_index(u64 flags) 
		return BTRFS_RAID_RAID1;

	else if (flags & BTRFS_BLOCK_GROUP_RAID1C3)

		return BTRFS_RAID_RAID1C3;

	else if (flags & BTRFS_BLOCK_GROUP_RAID1C4)

		return BTRFS_RAID_RAID1C4;

	else if (flags & BTRFS_BLOCK_GROUP_DUP)

		return BTRFS_RAID_DUP;

	else if (flags & BTRFS_BLOCK_GROUP_RAID0)

include/uapi/linux/btrfs.h

+1 −0
Original line number Diff line number Diff line
@@ -833,6 +833,7 @@ enum btrfs_err_code { 
	BTRFS_ERROR_DEV_ONLY_WRITABLE,

	BTRFS_ERROR_DEV_EXCL_RUN_IN_PROGRESS,

	BTRFS_ERROR_DEV_RAID1C3_MIN_NOT_MET,

	BTRFS_ERROR_DEV_RAID1C4_MIN_NOT_MET,

};



#define BTRFS_IOC_SNAP_CREATE _IOW(BTRFS_IOCTL_MAGIC, 1, \

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