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: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index aa1b437..923a880 100644 (file)
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -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
 

diff --git a/fs/btrfs/super.c b/fs/btrfs/super.c
index a5aff13..a98c3c7 100644 (file)
--- a/fs/btrfs/super.c
+++ b/fs/btrfs/super.c
@@ -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;
 

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index d17835f..9054203 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -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,

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index a4e26b8..46987a2 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -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)

diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
index ba22f91..a2b7612 100644 (file)
--- a/include/uapi/linux/btrfs.h
+++ b/include/uapi/linux/btrfs.h
@@ -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, \

diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
index 52b2964..8e322e2 100644 (file)
--- a/include/uapi/linux/btrfs_tree.h
+++ b/include/uapi/linux/btrfs_tree.h
@@ -842,6 +842,7 @@ struct btrfs_dev_replace_item {
 #define BTRFS_BLOCK_GROUP_RAID5         (1ULL << 7)
 #define BTRFS_BLOCK_GROUP_RAID6         (1ULL << 8)
 #define BTRFS_BLOCK_GROUP_RAID1C3       (1ULL << 9)
+#define BTRFS_BLOCK_GROUP_RAID1C4       (1ULL << 10)
 #define BTRFS_BLOCK_GROUP_RESERVED     (BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
                                         BTRFS_SPACE_INFO_GLOBAL_RSV)
 
@@ -854,6 +855,7 @@ enum btrfs_raid_types {
        BTRFS_RAID_RAID5,
        BTRFS_RAID_RAID6,
        BTRFS_RAID_RAID1C3,
+       BTRFS_RAID_RAID1C4,
        BTRFS_NR_RAID_TYPES
 };
 
@@ -864,6 +866,7 @@ enum btrfs_raid_types {
 #define BTRFS_BLOCK_GROUP_PROFILE_MASK (BTRFS_BLOCK_GROUP_RAID0 |   \
                                         BTRFS_BLOCK_GROUP_RAID1 |   \
                                         BTRFS_BLOCK_GROUP_RAID1C3 | \
+                                        BTRFS_BLOCK_GROUP_RAID1C4 | \
                                         BTRFS_BLOCK_GROUP_RAID5 |   \
                                         BTRFS_BLOCK_GROUP_RAID6 |   \
                                         BTRFS_BLOCK_GROUP_DUP |     \
@@ -872,7 +875,8 @@ enum btrfs_raid_types {
                                         BTRFS_BLOCK_GROUP_RAID6)
 
 #define BTRFS_BLOCK_GROUP_RAID1_MASK   (BTRFS_BLOCK_GROUP_RAID1 |   \
-                                        BTRFS_BLOCK_GROUP_RAID1C3)
+                                        BTRFS_BLOCK_GROUP_RAID1C3 | \
+                                        BTRFS_BLOCK_GROUP_RAID1C4)
 
 /*
  * We need a bit for restriper to be able to tell when chunks of type