Re: [PATCH 2/2] Btrfs: make raid attr array more readable

[Matthias Prager <linux@matthiasprager.de>]

One small error (see below):

> As the title said, this patch just make raid attr array more readable.
> 
> Cc: Liu Bo <bo.li.liu@oracle.com>
> Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
> ---
>  fs/btrfs/ctree.h       | 10 +++++++++-
>  fs/btrfs/extent-tree.c | 22 +++++++++-------------
>  fs/btrfs/volumes.c     | 47 +++++++++++++++++++++++++++++++++++++++++------
>  3 files changed, 59 insertions(+), 20 deletions(-)
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 9ee099f..541ce9a 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -953,7 +953,15 @@ struct btrfs_dev_replace_item {
>  #define BTRFS_BLOCK_GROUP_DUP		(1ULL << 5)
>  #define BTRFS_BLOCK_GROUP_RAID10	(1ULL << 6)
>  #define BTRFS_BLOCK_GROUP_RESERVED	BTRFS_AVAIL_ALLOC_BIT_SINGLE
> -#define BTRFS_NR_RAID_TYPES		5
> +
> +enum btrfs_raid_types {
> +	BTRFS_RAID_RAID10,
> +	BTRFS_RAID_RAID1,
> +	BTRFS_RAID_DUP,
> +	BTRFS_RAID_RAID0,
> +	BTRFS_RAID_SINGLE,
> +	BTRFS_NR_RAID_TYPES
> +};
>  
>  #define BTRFS_BLOCK_GROUP_TYPE_MASK	(BTRFS_BLOCK_GROUP_DATA |    \
>  					 BTRFS_BLOCK_GROUP_SYSTEM |  \
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index e68585d..6de0621 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -5547,20 +5547,16 @@ wait_block_group_cache_done(struct btrfs_block_group_cache *cache)
>  
>  int __get_raid_index(u64 flags)
>  {
> -	int index;
> -
>  	if (flags & BTRFS_BLOCK_GROUP_RAID10)
> -		index = 0;
> +		return BTRFS_RAID_RAID10;
>  	else if (flags & BTRFS_BLOCK_GROUP_RAID1)
> -		index = 1;
> +		return BTRFS_RAID_RAID1;
>  	else if (flags & BTRFS_BLOCK_GROUP_DUP)
> -		index = 2;
> +		return BTRFS_RAID_DUP;
>  	else if (flags & BTRFS_BLOCK_GROUP_RAID0)
> -		index = 3;
> +		return BTRFS_RAID_RAID0;
>  	else
> -		index = 4;
> -
> -	return index;
> +		return BTRFS_RAID_SINGLE;
>  }
>  
>  static int get_block_group_index(struct btrfs_block_group_cache *cache)
> @@ -7520,16 +7516,16 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
>  		index = get_block_group_index(block_group);
>  	}
>  
> -	if (index == 0) {
> +	if (index == BTRFS_RAID_RAID10) {
>  		dev_min = 4;
>  		/* Divide by 2 */
>  		min_free >>= 1;
> -	} else if (index == 1) {
> +	} else if (index == BTRFS_RAID_RAID1) {
>  		dev_min = 2;
> -	} else if (index == 2) {
> +	} else if (index == BTRFS_RAID_DUP) {
>  		/* Multiply by 2 */
>  		min_free <<= 1;
> -	} else if (index == 3) {
> +	} else if (index == BTRFS_RAID_RAID0) {
>  		dev_min = fs_devices->rw_devices;
>  		do_div(min_free, dev_min);
>  	}
> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
> index 7fa9773..edc5ee3 100644
> --- a/fs/btrfs/volumes.c
> +++ b/fs/btrfs/volumes.c
> @@ -3492,13 +3492,48 @@ static int btrfs_cmp_device_info(const void *a, const void *b)
>  }
>  
>  struct btrfs_raid_attr btrfs_raid_array[BTRFS_NR_RAID_TYPES] = {
> -	{ 2, 1, 0, 4, 2, 2 /* raid10 */ },
> -	{ 1, 1, 2, 2, 2, 2 /* raid1 */ },
> -	{ 1, 2, 1, 1, 1, 2 /* dup */ },
> -	{ 1, 1, 0, 2, 1, 1 /* raid0 */ },
> -	{ 1, 1, 1, 1, 1, 1 /* single */ },
> +	[BTRFS_RAID_RAID10] = {
> +		.sub_stripes	= 2,
> +		.dev_stripes	= 1,
> +		.devs_max	= 0,	/* 0 == as many as possible */
> +		.devs_min	= 4,
> +		.devs_increment	= 2,
> +		.ncopies	= 2,
> +	},
> +	[BTRFS_RAID_RAID1] = {
> +		.sub_stripes	= 1,
> +		.dev_stripes	= 1,
> +		.devs_max	= 2,
> +		.devs_min	= 2,
> +		.devs_increment	= 2,
> +		.ncopies	= 2,
> +	},
> +	[BTRFS_RAID_DUP] = {
> +		.sub_stripes	= 1,
> +		.dev_stripes	= 2,
> +		.devs_max	= 1,
> +		.devs_min	= 1,
> +		.devs_increment	= 1,
> +		.ncopies	= 2,
> +	},
> +	[BTRFS_RAID_RAID0] = {
> +		.sub_stripes	= 1,
> +		.dev_stripes	= 1,
> +		.devs_max	= 0,
> +		.devs_min	= 2,
> +		.devs_increment	= 1,
> +		.ncopies	= 1,
> +	},
> +	[BTRFS_RAID_RAID0] = {

Shouldn't this rather be BTRFS_RAID_SINGLE ?

> +		.sub_stripes	= 1,
> +		.dev_stripes	= 1,
> +		.devs_max	= 1,
> +		.devs_min	= 1,
> +		.devs_increment	= 1,
> +		.ncopies	= 1,
> +	},
>  };
> -
> + 
>  static int __btrfs_alloc_chunk(struct btrfs_trans_handle *trans,
>  			       struct btrfs_root *extent_root,
>  			       struct map_lookup **map_ret,
> -- 
> 1.7.11.7
> --
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