Commit 1e4eb746 authored by David Sterba's avatar David Sterba
Browse files

btrfs: switch compression callbacks to direct calls 



The indirect calls bring some overhead due to spectre vulnerability
mitigations. The number of cases is small and below the threshold
(10-20) where indirect call would be better.

Reviewed-by: default avatarJohannes Thumshirn <jthumshirn@suse.de>
Reviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
parent c4bf665a

fs/btrfs/compression.c

+69 −8
Original line number Diff line number Diff line
@@ -86,6 +86,70 @@ bool btrfs_compress_is_valid_type(const char *str, size_t len) 
	return false;

}



static int compression_compress_pages(int type, struct list_head *ws,

               struct address_space *mapping, u64 start, struct page **pages,

               unsigned long *out_pages, unsigned long *total_in,

               unsigned long *total_out)

{

	switch (type) {

	case BTRFS_COMPRESS_ZLIB:

		return zlib_compress_pages(ws, mapping, start, pages,

				out_pages, total_in, total_out);

	case BTRFS_COMPRESS_LZO:

		return lzo_compress_pages(ws, mapping, start, pages,

				out_pages, total_in, total_out);

	case BTRFS_COMPRESS_ZSTD:

		return zstd_compress_pages(ws, mapping, start, pages,

				out_pages, total_in, total_out);

	case BTRFS_COMPRESS_NONE:

	default:

		/*

		 * This can't happen, the type is validated several times

		 * before we get here. As a sane fallback, return what the

		 * callers will understand as 'no compression happened'.

		 */

		return -E2BIG;

	}

}



static int compression_decompress_bio(int type, struct list_head *ws,

		struct compressed_bio *cb)

{

	switch (type) {

	case BTRFS_COMPRESS_ZLIB: return zlib_decompress_bio(ws, cb);

	case BTRFS_COMPRESS_LZO:  return lzo_decompress_bio(ws, cb);

	case BTRFS_COMPRESS_ZSTD: return zstd_decompress_bio(ws, cb);

	case BTRFS_COMPRESS_NONE:

	default:

		/*

		 * This can't happen, the type is validated several times

		 * before we get here.

		 */

		BUG();

	}

}



static int compression_decompress(int type, struct list_head *ws,

               unsigned char *data_in, struct page *dest_page,

               unsigned long start_byte, size_t srclen, size_t destlen)

{

	switch (type) {

	case BTRFS_COMPRESS_ZLIB: return zlib_decompress(ws, data_in, dest_page,

						start_byte, srclen, destlen);

	case BTRFS_COMPRESS_LZO:  return lzo_decompress(ws, data_in, dest_page,

						start_byte, srclen, destlen);

	case BTRFS_COMPRESS_ZSTD: return zstd_decompress(ws, data_in, dest_page,

						start_byte, srclen, destlen);

	case BTRFS_COMPRESS_NONE:

	default:

		/*

		 * This can't happen, the type is validated several times

		 * before we get here.

		 */

		BUG();

	}

}



static int btrfs_decompress_bio(struct compressed_bio *cb);



static inline int compressed_bio_size(struct btrfs_fs_info *fs_info,
@@ -1074,10 +1138,8 @@ int btrfs_compress_pages(unsigned int type_level, struct address_space *mapping, 


	level = btrfs_compress_set_level(type, level);

	workspace = get_workspace(type, level);

	ret = btrfs_compress_op[type]->compress_pages(workspace, mapping,

						      start, pages,

						      out_pages,

						      total_in, total_out);

	ret = compression_compress_pages(type, workspace, mapping, start, pages,

					 out_pages, total_in, total_out);

	put_workspace(type, workspace);

	return ret;

}
@@ -1103,7 +1165,7 @@ static int btrfs_decompress_bio(struct compressed_bio *cb) 
	int type = cb->compress_type;



	workspace = get_workspace(type, 0);

	ret = btrfs_compress_op[type]->decompress_bio(workspace, cb);

	ret = compression_decompress_bio(type, workspace, cb);

	put_workspace(type, workspace);



	return ret;
@@ -1121,9 +1183,8 @@ int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page, 
	int ret;



	workspace = get_workspace(type, 0);

	ret = btrfs_compress_op[type]->decompress(workspace, data_in,

						  dest_page, start_byte,

						  srclen, destlen);

	ret = compression_decompress(type, workspace, data_in, dest_page,

				     start_byte, srclen, destlen);

	put_workspace(type, workspace);



	return ret;

fs/btrfs/compression.h

+0 −17
Original line number Diff line number Diff line
@@ -140,23 +140,6 @@ struct btrfs_compress_op { 


	void (*free_workspace)(struct list_head *workspace);



	int (*compress_pages)(struct list_head *workspace,

			      struct address_space *mapping,

			      u64 start,

			      struct page **pages,

			      unsigned long *out_pages,

			      unsigned long *total_in,

			      unsigned long *total_out);



	int (*decompress_bio)(struct list_head *workspace,

				struct compressed_bio *cb);



	int (*decompress)(struct list_head *workspace,

			  unsigned char *data_in,

			  struct page *dest_page,

			  unsigned long start_byte,

			  size_t srclen, size_t destlen);



	/* Maximum level supported by the compression algorithm */

	unsigned int max_level;

	unsigned int default_level;

fs/btrfs/lzo.c

+0 −3
Original line number Diff line number Diff line
@@ -509,9 +509,6 @@ const struct btrfs_compress_op btrfs_lzo_compress = { 
	.put_workspace		= lzo_put_workspace,

	.alloc_workspace	= lzo_alloc_workspace,

	.free_workspace		= lzo_free_workspace,

	.compress_pages		= lzo_compress_pages,

	.decompress_bio		= lzo_decompress_bio,

	.decompress		= lzo_decompress,

	.max_level		= 1,

	.default_level		= 1,

};

fs/btrfs/zlib.c

+0 −3
Original line number Diff line number Diff line
@@ -420,9 +420,6 @@ const struct btrfs_compress_op btrfs_zlib_compress = { 
	.put_workspace		= zlib_put_workspace,

	.alloc_workspace	= zlib_alloc_workspace,

	.free_workspace		= zlib_free_workspace,

	.compress_pages		= zlib_compress_pages,

	.decompress_bio		= zlib_decompress_bio,

	.decompress		= zlib_decompress,

	.max_level		= 9,

	.default_level		= BTRFS_ZLIB_DEFAULT_LEVEL,

};

fs/btrfs/zstd.c

+0 −3
Original line number Diff line number Diff line
@@ -713,9 +713,6 @@ const struct btrfs_compress_op btrfs_zstd_compress = { 
	.put_workspace = zstd_put_workspace,

	.alloc_workspace = zstd_alloc_workspace,

	.free_workspace = zstd_free_workspace,

	.compress_pages = zstd_compress_pages,

	.decompress_bio = zstd_decompress_bio,

	.decompress = zstd_decompress,

	.max_level	= ZSTD_BTRFS_MAX_LEVEL,

	.default_level	= ZSTD_BTRFS_DEFAULT_LEVEL,

};

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