diff options
author | Li Zefan <lizf@cn.fujitsu.com> | 2010-11-08 07:22:19 (GMT) |
---|---|---|
committer | Li Zefan <lizf@cn.fujitsu.com> | 2010-12-22 15:15:50 (GMT) |
commit | 3a39c18d63fec35f49df577d4b2a4e29c2212f22 (patch) | |
tree | 78b8c032e18e2231c18e89ac3f8f5746abdb119c /fs/btrfs/compression.c | |
parent | 1a419d85a76853d7d04e9b6280a80e96770bf3e3 (diff) | |
download | linux-fsl-qoriq-3a39c18d63fec35f49df577d4b2a4e29c2212f22.tar.xz |
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>
Diffstat (limited to 'fs/btrfs/compression.c')
-rw-r--r-- | fs/btrfs/compression.c | 92 |
1 files changed, 92 insertions, 0 deletions
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c index 8faa2df..f745287 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; +} |