Commit eb357060 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: raid56: introduce btrfs_raid_bio::stripe_sectors 



The new member is an array of sector_ptr pointers, they will represent
all sectors inside a full stripe (including P/Q).

They co-operate with btrfs_raid_bio::stripe_pages:

stripe_pages:   | Page 0, range [0, 64K)   | Page 1 ...
stripe_sectors: |  |  | ...             |  |
                |  |                    \- sector 15, page 0, pgoff=60K
                |  \- sector 1, page 0, pgoff=4K
                \---- sector 0, page 0, pfoff=0

With such structure, we can represent subpage sectors without using
extra pages.

Here we introduce a new helper, index_stripe_sectors(), to update
stripe_sectors[] to point to correct page and pgoff.

So every time rbio::stripe_pages[] pointer gets updated, the new helper
should be called.

The following functions have to call the new helper:

- steal_rbio()
- alloc_rbio_pages()
- alloc_rbio_parity_pages()
- alloc_rbio_essential_pages()

Signed-off-by: default avatarQu Wenruo <wqu@suse.com>
Reviewed-by: default avatarDavid Sterba <dsterba@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent 94efbe19

fs/btrfs/raid56.c

+56 −4
Original line number Diff line number Diff line
@@ -52,6 +52,16 @@ struct btrfs_stripe_hash_table { 
	struct btrfs_stripe_hash table[];

};



/*

 * A bvec like structure to present a sector inside a page.

 *

 * Unlike bvec we don't need bvlen, as it's fixed to sectorsize.

 */

struct sector_ptr {

	struct page *page;

	unsigned int pgoff;

};



enum btrfs_rbio_ops {

	BTRFS_RBIO_WRITE,

	BTRFS_RBIO_READ_REBUILD,
@@ -171,8 +181,12 @@ struct btrfs_raid_bio { 
	struct page **bio_pages;



	/*

	 * bitmap to record which horizontal stripe has data

	 * For subpage support, we need to map each sector to above

	 * stripe_pages.

	 */

	struct sector_ptr *stripe_sectors;



	/* Bitmap to record which horizontal stripe has data */

	unsigned long *dbitmap;



	/* allocated with real_stripes-many pointers for finish_*() calls */
@@ -291,6 +305,26 @@ static int rbio_bucket(struct btrfs_raid_bio *rbio) 
	return hash_64(num >> 16, BTRFS_STRIPE_HASH_TABLE_BITS);

}



/*

 * Update the stripe_sectors[] array to use correct page and pgoff

 *

 * Should be called every time any page pointer in stripes_pages[] got modified.

 */

static void index_stripe_sectors(struct btrfs_raid_bio *rbio)

{

	const u32 sectorsize = rbio->bioc->fs_info->sectorsize;

	u32 offset;

	int i;



	for (i = 0, offset = 0; i < rbio->nr_sectors; i++, offset += sectorsize) {

		int page_index = offset >> PAGE_SHIFT;



		ASSERT(page_index < rbio->nr_pages);

		rbio->stripe_sectors[i].page = rbio->stripe_pages[page_index];

		rbio->stripe_sectors[i].pgoff = offset_in_page(offset);

	}

}



/*

 * stealing an rbio means taking all the uptodate pages from the stripe

 * array in the source rbio and putting them into the destination rbio
@@ -317,6 +351,8 @@ static void steal_rbio(struct btrfs_raid_bio *src, struct btrfs_raid_bio *dest) 
		dest->stripe_pages[i] = s;

		src->stripe_pages[i] = NULL;

	}

	index_stripe_sectors(dest);

	index_stripe_sectors(src);

}



/*
@@ -977,6 +1013,7 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info, 
	rbio = kzalloc(sizeof(*rbio) +

		       sizeof(*rbio->stripe_pages) * num_pages +

		       sizeof(*rbio->bio_pages) * num_pages +

		       sizeof(*rbio->stripe_sectors) * num_sectors +

		       sizeof(*rbio->finish_pointers) * real_stripes +

		       sizeof(*rbio->dbitmap) * BITS_TO_LONGS(stripe_nsectors) +

		       sizeof(*rbio->finish_pbitmap) * BITS_TO_LONGS(stripe_nsectors),
@@ -1013,6 +1050,7 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info, 
	} while (0)

	CONSUME_ALLOC(rbio->stripe_pages, num_pages);

	CONSUME_ALLOC(rbio->bio_pages, num_pages);

	CONSUME_ALLOC(rbio->stripe_sectors, num_sectors);

	CONSUME_ALLOC(rbio->finish_pointers, real_stripes);

	CONSUME_ALLOC(rbio->dbitmap, BITS_TO_LONGS(stripe_nsectors));

	CONSUME_ALLOC(rbio->finish_pbitmap, BITS_TO_LONGS(stripe_nsectors));
@@ -1032,16 +1070,29 @@ static struct btrfs_raid_bio *alloc_rbio(struct btrfs_fs_info *fs_info, 
/* allocate pages for all the stripes in the bio, including parity */

static int alloc_rbio_pages(struct btrfs_raid_bio *rbio)

{

	return btrfs_alloc_page_array(rbio->nr_pages, rbio->stripe_pages);

	int ret;



	ret = btrfs_alloc_page_array(rbio->nr_pages, rbio->stripe_pages);

	if (ret < 0)

		return ret;

	/* Mapping all sectors */

	index_stripe_sectors(rbio);

	return 0;

}



/* only allocate pages for p/q stripes */

static int alloc_rbio_parity_pages(struct btrfs_raid_bio *rbio)

{

	int data_pages = rbio_stripe_page_index(rbio, rbio->nr_data, 0);

	int ret;



	return btrfs_alloc_page_array(rbio->nr_pages - data_pages,

	ret = btrfs_alloc_page_array(rbio->nr_pages - data_pages,

				     rbio->stripe_pages + data_pages);

	if (ret < 0)

		return ret;



	index_stripe_sectors(rbio);

	return 0;

}



/*
@@ -2283,6 +2334,7 @@ static int alloc_rbio_essential_pages(struct btrfs_raid_bio *rbio) 
			rbio->stripe_pages[index] = page;

		}

	}

	index_stripe_sectors(rbio);

	return 0;

}