Commit c5117327 authored by Qu Wenruo's avatar Qu Wenruo Committed by David Sterba
Browse files

btrfs: introduce btrfs_compress_bio() helper 



The helper will allocate a new compressed_bio, do the compression, and
return it to the caller.

This greatly simplifies the compression path, as we no longer need to
allocate a folio array thus no extra error path, furthermore the
compressed bio structure can be utilized for submission with very minor
modifications (like rounding up the bi_size and populate the bi_sector).

Reviewed-by: default avatarBoris Burkov <boris@bur.io>
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 3d74a755

fs/btrfs/compression.c

+68 −0
Original line number Diff line number Diff line
@@ -1064,6 +1064,74 @@ int btrfs_compress_folios(unsigned int type, int level, struct btrfs_inode *inod 
	return ret;

}



/*

 * Given an address space and start and length, compress the page cache

 * contents into @cb.

 *

 * @type_level:      is encoded algorithm and level, where level 0 means whatever

 *                   default the algorithm chooses and is opaque here;

 *                   - compression algo are 0-3

 *                   - the level are bits 4-7

 *

 * @cb->bbio.bio.bi_iter.bi_size will indicate the compressed data size.

 * The bi_size may not be sectorsize aligned, thus the caller still need

 * to do the round up before submission.

 *

 * This function will allocate compressed folios with btrfs_alloc_compr_folio(),

 * thus callers must make sure the endio function and error handling are using

 * btrfs_free_compr_folio() to release those folios.

 * This is already done in end_bbio_compressed_write() and cleanup_compressed_bio().

 */

struct compressed_bio *btrfs_compress_bio(struct btrfs_inode *inode,

					  u64 start, u32 len, unsigned int type,

					  int level, blk_opf_t write_flags)

{

	struct btrfs_fs_info *fs_info = inode->root->fs_info;

	struct list_head *workspace;

	struct compressed_bio *cb;

	int ret;



	cb = alloc_compressed_bio(inode, start, REQ_OP_WRITE | write_flags,

				  end_bbio_compressed_write);

	cb->start = start;

	cb->len = len;

	cb->writeback = true;

	cb->compress_type = type;



	level = btrfs_compress_set_level(type, level);

	workspace = get_workspace(fs_info, type, level);

	switch (type) {

	case BTRFS_COMPRESS_ZLIB:

		ret = zlib_compress_bio(workspace, cb);

		break;

	case BTRFS_COMPRESS_LZO:

		ret = lzo_compress_bio(workspace, cb);

		break;

	case BTRFS_COMPRESS_ZSTD:

		ret = zstd_compress_bio(workspace, cb);

		break;

	case BTRFS_COMPRESS_NONE:

	default:

		/*

		 * This can happen when compression races with remount setting

		 * it to 'no compress', while caller doesn't call

		 * inode_need_compress() to check if we really need to

		 * compress.

		 *

		 * Not a big deal, just need to inform caller that we

		 * haven't allocated any pages yet.

		 */

		ret = -E2BIG;

	}



	put_workspace(fs_info, type, workspace);

	if (ret < 0) {

		cleanup_compressed_bio(cb);

		return ERR_PTR(ret);

	}

	return cb;

}



static int btrfs_decompress_bio(struct compressed_bio *cb)

{

	struct btrfs_fs_info *fs_info = cb_to_fs_info(cb);

fs/btrfs/compression.h

+13 −0
Original line number Diff line number Diff line
@@ -146,6 +146,19 @@ int btrfs_compress_heuristic(struct btrfs_inode *inode, u64 start, u64 end); 


int btrfs_compress_filemap_get_folio(struct address_space *mapping, u64 start,

				     struct folio **in_folio_ret);

struct compressed_bio *btrfs_compress_bio(struct btrfs_inode *inode,

					  u64 start, u32 len, unsigned int type,

					  int level, blk_opf_t write_flags);



static inline void cleanup_compressed_bio(struct compressed_bio *cb)

{

	struct bio *bio = &cb->bbio.bio;

	struct folio_iter fi;



	bio_for_each_folio_all(fi, bio)

		btrfs_free_compr_folio(fi.folio);

	bio_put(bio);

}



int zlib_compress_folios(struct list_head *ws, struct btrfs_inode *inode,

			 u64 start, struct folio **folios, unsigned long *out_folios,