btrfs: introduce nparity raid_attr

Instead of hardcoding exceptions for RAID5 and RAID6 in the code, use an
nparity field in raid_attr.

Signed-off-by: Hans van Kranenburg <hans.van.kranenburg@mendix.com>
Signed-off-by: David Sterba <dsterba@suse.com>

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 2326179..29fc8a0 100644 (file)
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -37,6 +37,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .tolerated_failures = 1,
                .devs_increment = 2,
                .ncopies        = 2,
+               .nparity        = 0,
                .raid_name      = "raid10",
                .bg_flag        = BTRFS_BLOCK_GROUP_RAID10,
                .mindev_error   = BTRFS_ERROR_DEV_RAID10_MIN_NOT_MET,
@@ -49,6 +50,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .tolerated_failures = 1,
                .devs_increment = 2,
                .ncopies        = 2,
+               .nparity        = 0,
                .raid_name      = "raid1",
                .bg_flag        = BTRFS_BLOCK_GROUP_RAID1,
                .mindev_error   = BTRFS_ERROR_DEV_RAID1_MIN_NOT_MET,
@@ -61,6 +63,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .tolerated_failures = 0,
                .devs_increment = 1,
                .ncopies        = 2,
+               .nparity        = 0,
                .raid_name      = "dup",
                .bg_flag        = BTRFS_BLOCK_GROUP_DUP,
                .mindev_error   = 0,
@@ -73,6 +76,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .tolerated_failures = 0,
                .devs_increment = 1,
                .ncopies        = 1,
+               .nparity        = 0,
                .raid_name      = "raid0",
                .bg_flag        = BTRFS_BLOCK_GROUP_RAID0,
                .mindev_error   = 0,
@@ -85,6 +89,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .tolerated_failures = 0,
                .devs_increment = 1,
                .ncopies        = 1,
+               .nparity        = 0,
                .raid_name      = "single",
                .bg_flag        = 0,
                .mindev_error   = 0,
@@ -97,6 +102,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .tolerated_failures = 1,
                .devs_increment = 1,
                .ncopies        = 1,
+               .nparity        = 1,
                .raid_name      = "raid5",
                .bg_flag        = BTRFS_BLOCK_GROUP_RAID5,
                .mindev_error   = BTRFS_ERROR_DEV_RAID5_MIN_NOT_MET,
@@ -109,6 +115,7 @@ const struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
                .tolerated_failures = 2,
                .devs_increment = 1,
                .ncopies        = 1,
+               .nparity        = 2,
                .raid_name      = "raid6",
                .bg_flag        = BTRFS_BLOCK_GROUP_RAID6,
                .mindev_error   = BTRFS_ERROR_DEV_RAID6_MIN_NOT_MET,
@@ -4628,6 +4635,8 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        int devs_min;           /* min devs needed */
        int devs_increment;     /* ndevs has to be a multiple of this */
        int ncopies;            /* how many copies to data has */
+       int nparity;            /* number of stripes worth of bytes to
+                                  store parity information */
        int ret;
        u64 max_stripe_size;
        u64 max_chunk_size;
@@ -4654,6 +4663,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
        devs_min = btrfs_raid_array[index].devs_min;
        devs_increment = btrfs_raid_array[index].devs_increment;
        ncopies = btrfs_raid_array[index].ncopies;
+       nparity = btrfs_raid_array[index].nparity;
 
        if (type & BTRFS_BLOCK_GROUP_DATA) {
                max_stripe_size = SZ_1G;
@@ -4783,13 +4793,7 @@ static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
         * this will have to be fixed for RAID1 and RAID10 over
         * more drives
         */
-       data_stripes = num_stripes / ncopies;
-
-       if (type & BTRFS_BLOCK_GROUP_RAID5)
-               data_stripes = num_stripes - 1;
-
-       if (type & BTRFS_BLOCK_GROUP_RAID6)
-               data_stripes = num_stripes - 2;
+       data_stripes = (num_stripes - nparity) / ncopies;
 
        /*
         * Use the number of data stripes to figure out how big this chunk

diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index bca18f7..40820e0 100644 (file)
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -331,6 +331,8 @@ struct btrfs_raid_attr {
        int tolerated_failures; /* max tolerated fail devs */
        int devs_increment;     /* ndevs has to be a multiple of this */
        int ncopies;            /* how many copies to data has */
+       int nparity;            /* number of stripes worth of bytes to store
+                                * parity information */
        int mindev_error;       /* error code if min devs requisite is unmet */
        const char raid_name[8]; /* name of the raid */
        u64 bg_flag;            /* block group flag of the raid */