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>

4 files changed, 115 insertions, 194 deletions

diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 8faa2df9e719..f745287fbf2e 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -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;
+}
diff --git a/fs/btrfs/compression.h b/fs/btrfs/compression.h
index f7ce217113fa..51000174b9d7 100644
--- a/fs/btrfs/compression.h
+++ b/fs/btrfs/compression.h
@@ -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,
diff --git a/fs/btrfs/lzo.c b/fs/btrfs/lzo.c
index 523b144e2aec..cc9b450399df 100644
--- a/fs/btrfs/lzo.c
+++ b/fs/btrfs/lzo.c
@@ -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) {
@@ -359,97 +352,15 @@ cont:
                         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)
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;