On 5.10.2018 00:24, Hans van Kranenburg wrote:
> 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@xxxxxxxxxx>
> ---
> fs/btrfs/volumes.c | 18 +++++++++++-------
> fs/btrfs/volumes.h | 2 ++
> 2 files changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index d82b3d735ebe..453046497ac8 100644
> --- 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 = 2,
> .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,
> @@ -4597,6 +4604,8 @@ 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;
> @@ -4623,6 +4632,7 @@ 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;
> @@ -4752,13 +4762,7 @@ 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 23e9285d88de..0fe005b4295a 100644
> --- 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 */
The description can be simplified to: number of parity stripes
> 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 */
>
