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/block.c b/fs/squashfs/block.c
index 4dd4025..0cea9b9 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -36,6 +36,7 @@
#include "squashfs_fs_sb.h"
#include "squashfs.h"
#include "decompressor.h"
+#include "page_actor.h"
/*
* Read the metadata block length, this is stored in the first two
@@ -86,16 +87,16 @@
* generated a larger block - this does occasionally happen with compression
* algorithms).
*/
-int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
- int length, u64 *next_index, int srclength, int pages)
+int squashfs_read_data(struct super_block *sb, u64 index, int length,
+ u64 *next_index, struct squashfs_page_actor *output)
{
struct squashfs_sb_info *msblk = sb->s_fs_info;
struct buffer_head **bh;
int offset = index & ((1 << msblk->devblksize_log2) - 1);
u64 cur_index = index >> msblk->devblksize_log2;
- int bytes, compressed, b = 0, k = 0, page = 0, avail, i;
+ int bytes, compressed, b = 0, k = 0, avail, i;
- bh = kcalloc(((srclength + msblk->devblksize - 1)
+ bh = kcalloc(((output->length + msblk->devblksize - 1)
>> msblk->devblksize_log2) + 1, sizeof(*bh), GFP_KERNEL);
if (bh == NULL)
return -ENOMEM;
@@ -111,9 +112,9 @@
*next_index = index + length;
TRACE("Block @ 0x%llx, %scompressed size %d, src size %d\n",
- index, compressed ? "" : "un", length, srclength);
+ index, compressed ? "" : "un", length, output->length);
- if (length < 0 || length > srclength ||
+ if (length < 0 || length > output->length ||
(index + length) > msblk->bytes_used)
goto read_failure;
@@ -145,7 +146,7 @@
TRACE("Block @ 0x%llx, %scompressed size %d\n", index,
compressed ? "" : "un", length);
- if (length < 0 || length > srclength ||
+ if (length < 0 || length > output->length ||
(index + length) > msblk->bytes_used)
goto block_release;
@@ -165,8 +166,8 @@
}
if (compressed) {
- length = squashfs_decompress(msblk, buffer, bh, b, offset,
- length, srclength, pages);
+ length = squashfs_decompress(msblk, bh, b, offset, length,
+ output);
if (length < 0)
goto read_failure;
} else {
@@ -174,19 +175,20 @@
* Block is uncompressed.
*/
int in, pg_offset = 0;
+ void *data = squashfs_first_page(output);
for (bytes = length; k < b; k++) {
in = min(bytes, msblk->devblksize - offset);
bytes -= in;
while (in) {
if (pg_offset == PAGE_CACHE_SIZE) {
- page++;
+ data = squashfs_next_page(output);
pg_offset = 0;
}
avail = min_t(int, in, PAGE_CACHE_SIZE -
pg_offset);
- memcpy(buffer[page] + pg_offset,
- bh[k]->b_data + offset, avail);
+ memcpy(data + pg_offset, bh[k]->b_data + offset,
+ avail);
in -= avail;
pg_offset += avail;
offset += avail;
@@ -194,6 +196,7 @@
offset = 0;
put_bh(bh[k]);
}
+ squashfs_finish_page(output);
}
kfree(bh);