Squashfs: add LZ4 compression support

Add support for reading file systems compressed with the
LZ4 compression algorithm.

This patch adds the LZ4 decompressor wrapper code.

Signed-off-by: Phillip Lougher <phillip@squashfs.org.uk>

diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
new file mode 100644 (file)
index 0000000..c31e2bc
--- /dev/null
+++ b/fs/squashfs/lz4_wrapper.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2013, 2014
+ * Phillip Lougher <phillip@squashfs.org.uk>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2. See
+ * the COPYING file in the top-level directory.
+ */
+
+#include <linux/buffer_head.h>
+#include <linux/mutex.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/lz4.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs.h"
+#include "decompressor.h"
+#include "page_actor.h"
+
+#define LZ4_LEGACY     1
+
+struct lz4_comp_opts {
+       __le32 version;
+       __le32 flags;
+};
+
+struct squashfs_lz4 {
+       void *input;
+       void *output;
+};
+
+
+static void *lz4_comp_opts(struct squashfs_sb_info *msblk,
+       void *buff, int len)
+{
+       struct lz4_comp_opts *comp_opts = buff;
+
+       /* LZ4 compressed filesystems always have compression options */
+       if (comp_opts == NULL || len < sizeof(*comp_opts))
+               return ERR_PTR(-EIO);
+
+       if (le32_to_cpu(comp_opts->version) != LZ4_LEGACY) {
+               /* LZ4 format currently used by the kernel is the 'legacy'
+                * format */
+               ERROR("Unknown LZ4 version\n");
+               return ERR_PTR(-EINVAL);
+       }
+
+       return NULL;
+}
+
+
+static void *lz4_init(struct squashfs_sb_info *msblk, void *buff)
+{
+       int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
+       struct squashfs_lz4 *stream;
+
+       stream = kzalloc(sizeof(*stream), GFP_KERNEL);
+       if (stream == NULL)
+               goto failed;
+       stream->input = vmalloc(block_size);
+       if (stream->input == NULL)
+               goto failed2;
+       stream->output = vmalloc(block_size);
+       if (stream->output == NULL)
+               goto failed3;
+
+       return stream;
+
+failed3:
+       vfree(stream->input);
+failed2:
+       kfree(stream);
+failed:
+       ERROR("Failed to initialise LZ4 decompressor\n");
+       return ERR_PTR(-ENOMEM);
+}
+
+
+static void lz4_free(void *strm)
+{
+       struct squashfs_lz4 *stream = strm;
+
+       if (stream) {
+               vfree(stream->input);
+               vfree(stream->output);
+       }
+       kfree(stream);
+}
+
+
+static int lz4_uncompress(struct squashfs_sb_info *msblk, void *strm,
+       struct buffer_head **bh, int b, int offset, int length,
+       struct squashfs_page_actor *output)
+{
+       struct squashfs_lz4 *stream = strm;
+       void *buff = stream->input, *data;
+       int avail, i, bytes = length, res;
+       size_t dest_len = output->length;
+
+       for (i = 0; i < b; i++) {
+               avail = min(bytes, msblk->devblksize - offset);
+               memcpy(buff, bh[i]->b_data + offset, avail);
+               buff += avail;
+               bytes -= avail;
+               offset = 0;
+               put_bh(bh[i]);
+       }
+
+       res = lz4_decompress_unknownoutputsize(stream->input, length,
+                                       stream->output, &dest_len);
+       if (res)
+               return -EIO;
+
+       bytes = dest_len;
+       data = squashfs_first_page(output);
+       buff = stream->output;
+       while (data) {
+               if (bytes <= PAGE_CACHE_SIZE) {
+                       memcpy(data, buff, bytes);
+                       break;
+               }
+               memcpy(data, buff, PAGE_CACHE_SIZE);
+               buff += PAGE_CACHE_SIZE;
+               bytes -= PAGE_CACHE_SIZE;
+               data = squashfs_next_page(output);
+       }
+       squashfs_finish_page(output);
+
+       return dest_len;
+}
+
+const struct squashfs_decompressor squashfs_lz4_comp_ops = {
+       .init = lz4_init,
+       .comp_opts = lz4_comp_opts,
+       .free = lz4_free,
+       .decompress = lz4_uncompress,
+       .id = LZ4_COMPRESSION,
+       .name = "lz4",
+       .supported = 1
+};

diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index 4b2beda49498a39036d4db729d539042d1d750d5..506f4ba5b98309b9041cc99103312837b2724e58 100644 (file)
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -240,6 +240,7 @@ struct meta_index {
 #define LZMA_COMPRESSION       2
 #define LZO_COMPRESSION                3
 #define XZ_COMPRESSION         4
+#define LZ4_COMPRESSION                5
 
 struct squashfs_super_block {
        __le32                  s_magic;