Squashfs: Generalise paging handling in the decompressors
Further generalise the decompressors by adding a page handler
abstraction. This adds helpers to allow the decompressors
to access and process the output buffers in an implementation
independant manner.
This allows different types of output buffer to be passed
to the decompressors, with the implementation specific
aspects handled at decompression time, but without the
knowledge being held in the decompressor wrapper code.
This will allow the decompressors to handle Squashfs
cache buffers, and page cache pages.
This patch adds the abstraction and an implementation for
the caches.
Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>
Reviewed-by: Minchan Kim <minchan@kernel.org>
diff --git a/fs/squashfs/lzo_wrapper.c b/fs/squashfs/lzo_wrapper.c
index 75c3b57..244b9fb 100644
--- a/fs/squashfs/lzo_wrapper.c
+++ b/fs/squashfs/lzo_wrapper.c
@@ -31,6 +31,7 @@
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "decompressor.h"
+#include "page_actor.h"
struct squashfs_lzo {
void *input;
@@ -75,13 +76,13 @@
static int lzo_uncompress(struct squashfs_sb_info *msblk, void *strm,
- void **buffer, struct buffer_head **bh, int b, int offset, int length,
- int srclength, int pages)
+ struct buffer_head **bh, int b, int offset, int length,
+ struct squashfs_page_actor *output)
{
struct squashfs_lzo *stream = strm;
- void *buff = stream->input;
+ void *buff = stream->input, *data;
int avail, i, bytes = length, res;
- size_t out_len = srclength;
+ size_t out_len = output->length;
for (i = 0; i < b; i++) {
avail = min(bytes, msblk->devblksize - offset);
@@ -98,12 +99,20 @@
goto failed;
res = bytes = (int)out_len;
- for (i = 0, buff = stream->output; bytes && i < pages; i++) {
- avail = min_t(int, bytes, PAGE_CACHE_SIZE);
- memcpy(buffer[i], buff, avail);
- buff += avail;
- bytes -= avail;
+ data = squashfs_first_page(output);
+ buff = stream->output;
+ while (data) {
+ if (bytes <= PAGE_CACHE_SIZE) {
+ memcpy(data, buff, bytes);
+ break;
+ } else {
+ memcpy(data, buff, PAGE_CACHE_SIZE);
+ buff += PAGE_CACHE_SIZE;
+ bytes -= PAGE_CACHE_SIZE;
+ data = squashfs_next_page(output);
+ }
}
+ squashfs_finish_page(output);
return res;