btrfs: Extract duplicate decompress code

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

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>

1 files changed, 12 insertions, 99 deletions

diff --git a/fs/btrfs/zlib.c b/fs/btrfs/zlib.c
index 9a3e693917f2..f5ec2d44150d 100644
--- a/fs/btrfs/zlib.c
+++ b/fs/btrfs/zlib.c
@@ -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) {
-                                        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;
-                                }
-                        }
+                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;
                 }
-next:
+
                 workspace->inf_strm.next_out = workspace->buf;
                 workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;