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btrfs: Extract duplicate decompress code

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

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
This commit is contained in:
Li Zefan
2010-11-08 15:22:19 +08:00
parent 1a419d85a7
commit 3a39c18d63
4 changed files with 115 additions and 194 deletions
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111
fs/btrfs/zlib.c
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@@ -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;
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;
}
/* 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;
}
}
}
next:
workspace->inf_strm.next_out = workspace->buf;
workspace->inf_strm.avail_out = PAGE_CACHE_SIZE;