Commit 3a39c18d authored by Li Zefan's avatar Li Zefan
Browse files

btrfs: Extract duplicate decompress code 



Add a common function to copy decompressed data from working buffer
to bio pages.

Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
parent 1a419d85

fs/btrfs/compression.c

+92 −0
Original line number Diff line number Diff line
@@ -904,3 +904,95 @@ void __exit btrfs_exit_compress(void) 
{

	free_workspaces();

}



/*

 * Copy uncompressed data from working buffer to pages.

 *

 * buf_start is the byte offset we're of the start of our workspace buffer.

 *

 * total_out is the last byte of the buffer

 */

int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,

			      unsigned long total_out, u64 disk_start,

			      struct bio_vec *bvec, int vcnt,

			      unsigned long *page_index,

			      unsigned long *pg_offset)

{

	unsigned long buf_offset;

	unsigned long current_buf_start;

	unsigned long start_byte;

	unsigned long working_bytes = total_out - buf_start;

	unsigned long bytes;

	char *kaddr;

	struct page *page_out = bvec[*page_index].bv_page;



	/*

	 * start byte is the first byte of the page we're currently

	 * copying into relative to the start of the compressed data.

	 */

	start_byte = page_offset(page_out) - disk_start;



	/* we haven't yet hit data corresponding to this page */

	if (total_out <= start_byte)

		return 1;



	/*

	 * the start of the data we care about is offset into

	 * the middle of our working buffer

	 */

	if (total_out > start_byte && buf_start < start_byte) {

		buf_offset = start_byte - buf_start;

		working_bytes -= buf_offset;

	} else {

		buf_offset = 0;

	}

	current_buf_start = buf_start;



	/* copy bytes from the working buffer into the pages */

	while (working_bytes > 0) {

		bytes = min(PAGE_CACHE_SIZE - *pg_offset,

			    PAGE_CACHE_SIZE - buf_offset);

		bytes = min(bytes, working_bytes);

		kaddr = kmap_atomic(page_out, KM_USER0);

		memcpy(kaddr + *pg_offset, buf + buf_offset, bytes);

		kunmap_atomic(kaddr, KM_USER0);

		flush_dcache_page(page_out);



		*pg_offset += bytes;

		buf_offset += bytes;

		working_bytes -= bytes;

		current_buf_start += bytes;



		/* check if we need to pick another page */

		if (*pg_offset == PAGE_CACHE_SIZE) {

			(*page_index)++;

			if (*page_index >= vcnt)

				return 0;



			page_out = bvec[*page_index].bv_page;

			*pg_offset = 0;

			start_byte = page_offset(page_out) - disk_start;



			/*

			 * make sure our new page is covered by this

			 * working buffer

			 */

			if (total_out <= start_byte)

				return 1;



			/*

			 * the next page in the biovec might not be adjacent

			 * to the last page, but it might still be found

			 * inside this working buffer. bump our offset pointer

			 */

			if (total_out > start_byte &&

			    current_buf_start < start_byte) {

				buf_offset = start_byte - buf_start;

				working_bytes = total_out - start_byte;

				current_buf_start = buf_start + buf_offset;

			}

		}

	}



	return 1;

}

fs/btrfs/compression.h

+5 −0
Original line number Diff line number Diff line
@@ -34,6 +34,11 @@ int btrfs_decompress_biovec(int type, struct page **pages_in, u64 disk_start, 
			    struct bio_vec *bvec, int vcnt, size_t srclen);

int btrfs_decompress(int type, unsigned char *data_in, struct page *dest_page,

		     unsigned long start_byte, size_t srclen, size_t destlen);

int btrfs_decompress_buf2page(char *buf, unsigned long buf_start,

			      unsigned long total_out, u64 disk_start,

			      struct bio_vec *bvec, int vcnt,

			      unsigned long *page_index,

			      unsigned long *pg_offset);



int btrfs_submit_compressed_write(struct inode *inode, u64 start,

				  unsigned long len, u64 disk_start,

fs/btrfs/lzo.c

+6 −95
Original line number Diff line number Diff line
@@ -260,12 +260,10 @@ static int lzo_decompress_biovec(struct list_head *ws, 
				 size_t srclen)

{

	struct workspace *workspace = list_entry(ws, struct workspace, list);

	int ret = 0;

	int ret = 0, ret2;

	char *data_in;

	unsigned long page_bytes_left;

	unsigned long page_in_index = 0;

	unsigned long page_out_index = 0;

	struct page *page_out;

	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /

					PAGE_CACHE_SIZE;

	unsigned long buf_start;
@@ -273,9 +271,6 @@ static int lzo_decompress_biovec(struct list_head *ws, 
	unsigned long bytes;

	unsigned long working_bytes;

	unsigned long pg_offset;

	unsigned long start_byte;

	unsigned long current_buf_start;

	char *kaddr;



	size_t in_len;

	size_t out_len;
@@ -295,8 +290,6 @@ static int lzo_decompress_biovec(struct list_head *ws, 
	in_page_bytes_left = PAGE_CACHE_SIZE - LZO_LEN;



	tot_out = 0;

	page_out = bvec[0].bv_page;

	page_bytes_left = PAGE_CACHE_SIZE;

	pg_offset = 0;



	while (tot_in < tot_len) {
@@ -359,98 +352,16 @@ static int lzo_decompress_biovec(struct list_head *ws, 
			break;

		}



		/*

		 * buf start is the byte offset we're of the start of

		 * our workspace buffer

		 */

		buf_start = tot_out;



		/* tot_out is the last byte of the workspace buffer */

		tot_out += out_len;



		working_bytes = tot_out - buf_start;



		/*

		 * start_byte is the first byte of the page we're currently

		 * copying into relative to the start of the compressed data.

		 */

		start_byte = page_offset(page_out) - disk_start;



		if (working_bytes == 0) {

			/* we didn't make progress in this inflate

			 * call, we're done

			 */

		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,

						 tot_out, disk_start,

						 bvec, vcnt,

						 &page_out_index, &pg_offset);

		if (ret2 == 0)

			break;

	}



		/* we haven't yet hit data corresponding to this page */

		if (tot_out <= start_byte)

			continue;



		/*

		 * the start of the data we care about is offset into

		 * the middle of our working buffer

		 */

		if (tot_out > start_byte && buf_start < start_byte) {

			buf_offset = start_byte - buf_start;

			working_bytes -= buf_offset;

		} else {

			buf_offset = 0;

		}

		current_buf_start = buf_start;



		/* copy bytes from the working buffer into the pages */

		while (working_bytes > 0) {

			bytes = min(PAGE_CACHE_SIZE - pg_offset,

				    PAGE_CACHE_SIZE - buf_offset);

			bytes = min(bytes, working_bytes);

			kaddr = kmap_atomic(page_out, KM_USER0);

			memcpy(kaddr + pg_offset, workspace->buf + buf_offset,

			       bytes);

			kunmap_atomic(kaddr, KM_USER0);

			flush_dcache_page(page_out);



			pg_offset += bytes;

			page_bytes_left -= bytes;

			buf_offset += bytes;

			working_bytes -= bytes;

			current_buf_start += bytes;



			/* check if we need to pick another page */

			if (page_bytes_left == 0) {

				page_out_index++;

				if (page_out_index >= vcnt) {

					ret = 0;

					goto done;

				}



				page_out = bvec[page_out_index].bv_page;

				pg_offset = 0;

				page_bytes_left = PAGE_CACHE_SIZE;

				start_byte = page_offset(page_out) - disk_start;



				/*

				 * make sure our new page is covered by this

				 * working buffer

				 */

				if (tot_out <= start_byte)

					break;



				/* the next page in the biovec might not

				 * be adjacent to the last page, but it

				 * might still be found inside this working

				 * buffer.  bump our offset pointer

				 */

				if (tot_out > start_byte &&

				    current_buf_start < start_byte) {

					buf_offset = start_byte - buf_start;

					working_bytes = tot_out - start_byte;

					current_buf_start = buf_start +

						buf_offset;

				}

			}

		}

	}

done:

	if (data_in)

		kunmap(pages_in[page_in_index]);

fs/btrfs/zlib.c

+12 −99
Original line number Diff line number Diff line
@@ -218,24 +218,16 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in, 
				  size_t srclen)

{

	struct workspace *workspace = list_entry(ws, struct workspace, list);

	int ret = 0;

	int ret = 0, ret2;

	int wbits = MAX_WBITS;

	char *data_in;

	size_t total_out = 0;

	unsigned long page_bytes_left;

	unsigned long page_in_index = 0;

	unsigned long page_out_index = 0;

	struct page *page_out;

	unsigned long total_pages_in = (srclen + PAGE_CACHE_SIZE - 1) /

					PAGE_CACHE_SIZE;

	unsigned long buf_start;

	unsigned long buf_offset;

	unsigned long bytes;

	unsigned long working_bytes;

	unsigned long pg_offset;

	unsigned long start_byte;

	unsigned long current_buf_start;

	char *kaddr;



	data_in = kmap(pages_in[page_in_index]);

	workspace->inf_strm.next_in = data_in;
@@ -245,8 +237,6 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in, 
	workspace->inf_strm.total_out = 0;

	workspace->inf_strm.next_out = workspace->buf;

	workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;

	page_out = bvec[page_out_index].bv_page;

	page_bytes_left = PAGE_CACHE_SIZE;

	pg_offset = 0;



	/* If it's deflate, and it's got no preset dictionary, then
@@ -268,100 +258,23 @@ static int zlib_decompress_biovec(struct list_head *ws, struct page **pages_in, 
		ret = zlib_inflate(&workspace->inf_strm, Z_NO_FLUSH);

		if (ret != Z_OK && ret != Z_STREAM_END)

			break;

		/*

		 * buf start is the byte offset we're of the start of

		 * our workspace buffer

		 */

		buf_start = total_out;



		/* total_out is the last byte of the workspace buffer */

		buf_start = total_out;

		total_out = workspace->inf_strm.total_out;



		working_bytes = total_out - buf_start;



		/*

		 * start byte is the first byte of the page we're currently

		 * copying into relative to the start of the compressed data.

		 */

		start_byte = page_offset(page_out) - disk_start;



		if (working_bytes == 0) {

			/* we didn't make progress in this inflate

			 * call, we're done

			 */

			if (ret != Z_STREAM_END)

				ret = -1;

		/* we didn't make progress in this inflate call, we're done */

		if (buf_start == total_out)

			break;

		}



		/* we haven't yet hit data corresponding to this page */

		if (total_out <= start_byte)

			goto next;



		/*

		 * the start of the data we care about is offset into

		 * the middle of our working buffer

		 */

		if (total_out > start_byte && buf_start < start_byte) {

			buf_offset = start_byte - buf_start;

			working_bytes -= buf_offset;

		} else {

			buf_offset = 0;

		}

		current_buf_start = buf_start;



		/* copy bytes from the working buffer into the pages */

		while (working_bytes > 0) {

			bytes = min(PAGE_CACHE_SIZE - pg_offset,

				    PAGE_CACHE_SIZE - buf_offset);

			bytes = min(bytes, working_bytes);

			kaddr = kmap_atomic(page_out, KM_USER0);

			memcpy(kaddr + pg_offset, workspace->buf + buf_offset,

			       bytes);

			kunmap_atomic(kaddr, KM_USER0);

			flush_dcache_page(page_out);



			pg_offset += bytes;

			page_bytes_left -= bytes;

			buf_offset += bytes;

			working_bytes -= bytes;

			current_buf_start += bytes;



			/* check if we need to pick another page */

			if (page_bytes_left == 0) {

				page_out_index++;

				if (page_out_index >= vcnt) {

		ret2 = btrfs_decompress_buf2page(workspace->buf, buf_start,

						 total_out, disk_start,

						 bvec, vcnt,

						 &page_out_index, &pg_offset);

		if (ret2 == 0) {

			ret = 0;

			goto done;

		}



				page_out = bvec[page_out_index].bv_page;

				pg_offset = 0;

				page_bytes_left = PAGE_CACHE_SIZE;

				start_byte = page_offset(page_out) - disk_start;



				/*

				 * make sure our new page is covered by this

				 * working buffer

				 */

				if (total_out <= start_byte)

					goto next;



				/* the next page in the biovec might not

				 * be adjacent to the last page, but it

				 * might still be found inside this working

				 * buffer.  bump our offset pointer

				 */

				if (total_out > start_byte &&

				    current_buf_start < start_byte) {

					buf_offset = start_byte - buf_start;

					working_bytes = total_out - start_byte;

					current_buf_start = buf_start +

						buf_offset;

				}

			}

		}

next:

		workspace->inf_strm.next_out = workspace->buf;

		workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;