Re: [PATCH v2 06/19] btrfs-progs: Introduce new btrfs_map_block function which returns more unified result.

From: Liu Bo <bo.li.liu@oracle.com>
To: Qu Wenruo <quwenruo@cn.fujitsu.com>
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2 06/19] btrfs-progs: Introduce new btrfs_map_block function which returns more unified result.
Date: Thu, 23 Feb 2017 16:37:57 -0800	[thread overview]
Message-ID: <20170224003757.GC24959@lim.localdomain> (raw)
In-Reply-To: <20161226062939.5841-7-quwenruo@cn.fujitsu.com>

On Mon, Dec 26, 2016 at 02:29:26PM +0800, Qu Wenruo wrote:
> Introduce a new function, __btrfs_map_block_v2().
> 
> Unlike old btrfs_map_block(), which needs different parameter to handle
> different RAID profile, this new function uses unified btrfs_map_block
> structure to handle all RAID profile in a more meaningful method:
> 
> Return physical address along with logical address for each stripe.
> 
> For RAID1/Single/DUP (none-stripped):
> result would be like:
> Map block: Logical 128M, Len 10M, Type RAID1, Stripe len 0, Nr_stripes 2
> Stripe 0: Logical 128M, Physical X, Len: 10M Dev dev1
> Stripe 1: Logical 128M, Physical Y, Len: 10M Dev dev2
> 
> Result will be as long as possible, since it's not stripped at all.
> 
> For RAID0/10 (stripped without parity):
> Result will be aligned to full stripe size:
> Map block: Logical 64K, Len 128K, Type RAID10, Stripe len 64K, Nr_stripes 4
> Stripe 0: Logical 64K, Physical X, Len 64K Dev dev1
> Stripe 1: Logical 64K, Physical Y, Len 64K Dev dev2
> Stripe 2: Logical 128K, Physical Z, Len 64K Dev dev3
> Stripe 3: Logical 128K, Physical W, Len 64K Dev dev4
> 
> For RAID5/6 (stripped with parity and dev-rotation)
> Result will be aligned to full stripe size:
> Map block: Logical 64K, Len 128K, Type RAID6, Stripe len 64K, Nr_stripes 4
> Stripe 0: Logical 64K, Physical X, Len 64K Dev dev1
> Stripe 1: Logical 128K, Physical Y, Len 64K Dev dev2
> Stripe 2: Logical RAID5_P, Physical Z, Len 64K Dev dev3
> Stripe 3: Logical RAID6_Q, Physical W, Len 64K Dev dev4
> 
> The new unified layout should be very flex and can even handle things
> like N-way RAID1 (which old mirror_num basic one can't handle well).
> 
> Signed-off-by: Qu Wenruo <quwenruo@cn.fujitsu.com>
> ---
>  volumes.c | 181 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  volumes.h |  49 +++++++++++++++++
>  2 files changed, 230 insertions(+)
> 
> diff --git a/volumes.c b/volumes.c
> index f17bdeed..11d1f0e8 100644
> --- a/volumes.c
> +++ b/volumes.c
> @@ -1593,6 +1593,187 @@ out:
>  	return 0;
>  }
>  
> +static inline struct btrfs_map_block *alloc_map_block(int num_stripes)
> +{
> +	struct btrfs_map_block *ret;
> +	int size;
> +
> +	size = sizeof(struct btrfs_map_stripe) * num_stripes +
> +		sizeof(struct btrfs_map_block);
> +	ret = malloc(size);
> +	if (!ret)
> +		return NULL;
> +	memset(ret, 0, size);
> +	return ret;
> +}
> +
> +static int fill_full_map_block(struct map_lookup *map, u64 start, u64 length,
> +			       struct btrfs_map_block *map_block)
> +{
> +	u64 profile = map->type & BTRFS_BLOCK_GROUP_PROFILE_MASK;
> +	u64 bg_start = map->ce.start;
> +	u64 bg_end = bg_start + map->ce.size;
> +	u64 bg_offset = start - bg_start; /* offset inside the block group */
> +	u64 fstripe_logical = 0;	/* Full stripe start logical bytenr */
> +	u64 fstripe_size = 0;		/* Full stripe logical size */
> +	u64 fstripe_phy_off = 0;	/* Full stripe offset in each dev */
> +	u32 stripe_len = map->stripe_len;
> +	int sub_stripes = map->sub_stripes;
> +	int data_stripes = nr_data_stripes(map);
> +	int dev_rotation;
> +	int i;
> +
> +	map_block->num_stripes = map->num_stripes;
> +	map_block->type = profile;
> +
> +	/*
> +	 * Common full stripe data for stripe based profiles
> +	 */
> +	if (profile & (BTRFS_BLOCK_GROUP_RAID0 | BTRFS_BLOCK_GROUP_RAID10 |
> +		       BTRFS_BLOCK_GROUP_RAID5 | BTRFS_BLOCK_GROUP_RAID6)) {
> +		fstripe_size = stripe_len * data_stripes;
> +		if (sub_stripes)
> +			fstripe_size /= sub_stripes;
> +		fstripe_logical = bg_offset / fstripe_size * fstripe_size +
> +				    bg_start;
> +		fstripe_phy_off = bg_offset / fstripe_size * stripe_len;
> +	}
> +
> +	switch (profile) {
> +	case BTRFS_BLOCK_GROUP_DUP:
> +	case BTRFS_BLOCK_GROUP_RAID1:
> +	case 0: /* SINGLE */
> +		/*
> +		 * None-stripe mode,(Single, DUP and RAID1)
> +		 * Just use offset to fill map_block
> +		 */
> +		map_block->stripe_len = 0;
> +		map_block->start = start;
> +		map_block->length = min(bg_end, start + length) - start;
> +		for (i = 0; i < map->num_stripes; i++) {
> +			struct btrfs_map_stripe *stripe;
> +
> +			stripe = &map_block->stripes[i];
> +
> +			stripe->dev = map->stripes[i].dev;
> +			stripe->logical = start;
> +			stripe->physical = map->stripes[i].physical + bg_offset;
> +			stripe->length = map_block->length;
> +		}
> +		break;
> +	case BTRFS_BLOCK_GROUP_RAID10:
> +	case BTRFS_BLOCK_GROUP_RAID0:
> +		/*
> +		 * Stripe modes without parity(0 and 10)
> +		 * Return the whole full stripe
> +		 */
> +
> +		map_block->start = fstripe_logical;
> +		map_block->length = fstripe_size;
> +		map_block->stripe_len = map->stripe_len;
> +		for (i = 0; i < map->num_stripes; i++) {
> +			struct btrfs_map_stripe *stripe;
> +			u64 cur_offset;
> +
> +			/* Handle RAID10 sub stripes */
> +			if (sub_stripes)
> +				cur_offset = i / sub_stripes * stripe_len;
> +			else
> +				cur_offset = stripe_len * i;
> +			stripe = &map_block->stripes[i];
> +
> +			stripe->dev = map->stripes[i].dev;
> +			stripe->logical = fstripe_logical + cur_offset;
> +			stripe->length = stripe_len;
> +			stripe->physical = map->stripes[i].physical +
> +					   fstripe_phy_off;

Looks like @fstripe_phy_off refers to the start offset of the stripe on devices,
but we may ask for an offset inside the stripe.

Thanks,

-liubo

> +		}
> +		break;
> +	case BTRFS_BLOCK_GROUP_RAID5:
> +	case BTRFS_BLOCK_GROUP_RAID6:
> +		/*
> +		 * Stripe modes with parity and device rotation(5 and 6)
> +		 *
> +		 * Return the whole full stripe
> +		 */
> +
> +		dev_rotation = (bg_offset / fstripe_size) % map->num_stripes;
> +
> +		map_block->start = fstripe_logical;
> +		map_block->length = fstripe_size;
> +		map_block->stripe_len = map->stripe_len;
> +		for (i = 0; i < map->num_stripes; i++) {
> +			struct btrfs_map_stripe *stripe;
> +			int dest_index;
> +			u64 cur_offset = stripe_len * i;
> +
> +			stripe = &map_block->stripes[i];
> +
> +			dest_index = (i + dev_rotation) % map->num_stripes;
> +			stripe->dev = map->stripes[dest_index].dev;
> +			stripe->length = stripe_len;
> +			stripe->physical = map->stripes[dest_index].physical +
> +					   fstripe_phy_off;
> +			if (i < data_stripes) {
> +				/* data stripe */
> +				stripe->logical = fstripe_logical +
> +						  cur_offset;
> +			} else if (i == data_stripes) {
> +				/* P */
> +				stripe->logical = BTRFS_RAID5_P_STRIPE;
> +			} else {
> +				/* Q */
> +				stripe->logical = BTRFS_RAID6_Q_STRIPE;
> +			}
> +		}
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +	return 0;
> +}
> +
> +int __btrfs_map_block_v2(struct btrfs_fs_info *fs_info, int rw, u64 logical,
> +			 u64 length, struct btrfs_map_block **map_ret)
> +{
> +	struct cache_extent *ce;
> +	struct map_lookup *map;
> +	struct btrfs_map_block *map_block;
> +	int ret;
> +
> +	/* Eearly parameter check */
> +	if (!length || !map_ret) {
> +		error("wrong parameter for %s", __func__);
> +		return -EINVAL;
> +	}
> +
> +	ce = search_cache_extent(&fs_info->mapping_tree.cache_tree, logical);
> +	if (!ce)
> +		return -ENOENT;
> +	if (ce->start > logical)
> +		return -ENOENT;
> +
> +	map = container_of(ce, struct map_lookup, ce);
> +	/*
> +	 * Allocate a full map_block anyway
> +	 *
> +	 * For write, we need the full map_block anyway.
> +	 * For read, it will be striped to the needed stripe before returning.
> +	 */
> +	map_block = alloc_map_block(map->num_stripes);
> +	if (!map_block)
> +		return -ENOMEM;
> +	ret = fill_full_map_block(map, logical, length, map_block);
> +	if (ret < 0) {
> +		free(map_block);
> +		return ret;
> +	}
> +	/* TODO: Remove unrelated map_stripes for READ operation */
> +
> +	*map_ret = map_block;
> +	return 0;
> +}
> +
>  struct btrfs_device *btrfs_find_device(struct btrfs_root *root, u64 devid,
>  				       u8 *uuid, u8 *fsid)
>  {
> diff --git a/volumes.h b/volumes.h
> index ee7d56ab..0a575557 100644
> --- a/volumes.h
> +++ b/volumes.h
> @@ -108,6 +108,51 @@ struct map_lookup {
>  	struct btrfs_bio_stripe stripes[];
>  };
>  
> +struct btrfs_map_stripe {
> +	struct btrfs_device *dev;
> +
> +	/*
> +	 * Logical address of the stripe start.
> +	 * Caller should check if this logical is the desired map start.
> +	 * It's possible that the logical is smaller or larger than desired
> +	 * map range.
> +	 *
> +	 * For P/Q stipre, it will be BTRFS_RAID5_P_STRIPE
> +	 * and BTRFS_RAID6_Q_STRIPE.
> +	 */
> +	u64 logical;
> +
> +	u64 physical;
> +
> +	/* The length of the stripe */
> +	u64 length;
> +};
> +
> +struct btrfs_map_block {
> +	/*
> +	 * The logical start of the whole map block.
> +	 * For RAID5/6 it will be the bytenr of the full stripe start,
> +	 * so it's possible that @start is smaller than desired map range
> +	 * start.
> +	 */
> +	u64 start;
> +
> +	/*
> +	 * The logical length of the map block.
> +	 * For RAID5/6 it will be total data stripe size
> +	 */
> +	u64 length;
> +
> +	/* Block group type */
> +	u64 type;
> +
> +	/* Stripe length, for non-stripped mode, it will be 0 */
> +	u32 stripe_len;
> +
> +	int num_stripes;
> +	struct btrfs_map_stripe stripes[];
> +};
> +
>  #define btrfs_multi_bio_size(n) (sizeof(struct btrfs_multi_bio) + \
>  			    (sizeof(struct btrfs_bio_stripe) * (n)))
>  #define btrfs_map_lookup_size(n) (sizeof(struct map_lookup) + \
> @@ -187,6 +232,10 @@ int btrfs_map_block(struct btrfs_mapping_tree *map_tree, int rw,
>  		    u64 logical, u64 *length,
>  		    struct btrfs_multi_bio **multi_ret, int mirror_num,
>  		    u64 **raid_map_ret);
> +
> +/* TODO: Use this map_block_v2 to replace __btrfs_map_block() */
> +int __btrfs_map_block_v2(struct btrfs_fs_info *fs_info, int rw, u64 logical,
> +			 u64 length, struct btrfs_map_block **map_ret);
>  int btrfs_next_bg(struct btrfs_mapping_tree *map_tree, u64 *logical,
>  		     u64 *size, u64 type);
>  static inline int btrfs_next_bg_metadata(struct btrfs_mapping_tree *map_tree,
> -- 
> 2.11.0
> 
> 
> 
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