7 files changed, 174 insertions, 4 deletions

diff --git a/Documentation/filesystems/squashfs.txt b/Documentation/filesystems/squashfs.txt
index 403c090aca39..e5274f84dc56 100644
--- a/Documentation/filesystems/squashfs.txt
+++ b/Documentation/filesystems/squashfs.txt
@@ -2,10 +2,10 @@ SQUASHFS 4.0 FILESYSTEM
 =======================
 
 Squashfs is a compressed read-only filesystem for Linux.
-It uses zlib/lzo/xz compression to compress files, inodes and directories.
-Inodes in the system are very small and all blocks are packed to minimise
-data overhead. Block sizes greater than 4K are supported up to a maximum
-of 1Mbytes (default block size 128K).
+It uses zlib, lz4, lzo, or xz compression to compress files, inodes and
+directories.  Inodes in the system are very small and all blocks are packed to
+minimise data overhead. Block sizes greater than 4K are supported up to a
+maximum of 1Mbytes (default block size 128K).
 
 Squashfs is intended for general read-only filesystem use, for archival
 use (i.e. in cases where a .tar.gz file may be used), and in constrained
diff --git a/fs/squashfs/Kconfig b/fs/squashfs/Kconfig
index b6fa8657dcbc..ffb093e72b6c 100644
--- a/fs/squashfs/Kconfig
+++ b/fs/squashfs/Kconfig
@@ -120,6 +120,21 @@ config SQUASHFS_ZLIB
 
           If unsure, say Y.
 
+config SQUASHFS_LZ4
+        bool "Include support for LZ4 compressed file systems"
+        depends on SQUASHFS
+        select LZ4_DECOMPRESS
+        help
+          Saying Y here includes support for reading Squashfs file systems
+          compressed with LZ4 compression.  LZ4 compression is mainly
+          aimed at embedded systems with slower CPUs where the overheads
+          of zlib are too high.
+
+          LZ4 is not the standard compression used in Squashfs and so most
+          file systems will be readable without selecting this option.
+
+          If unsure, say N.
+
 config SQUASHFS_LZO
         bool "Include support for LZO compressed file systems"
         depends on SQUASHFS
diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index 4132520b4ff2..246a6f329d89 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -11,6 +11,7 @@ squashfs-$(CONFIG_SQUASHFS_DECOMP_SINGLE) += decompressor_single.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI) += decompressor_multi.o
 squashfs-$(CONFIG_SQUASHFS_DECOMP_MULTI_PERCPU) += decompressor_multi_percpu.o
 squashfs-$(CONFIG_SQUASHFS_XATTR) += xattr.o xattr_id.o
+squashfs-$(CONFIG_SQUASHFS_LZ4) += lz4_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_LZO) += lzo_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_XZ) += xz_wrapper.o
 squashfs-$(CONFIG_SQUASHFS_ZLIB) += zlib_wrapper.o
diff --git a/fs/squashfs/decompressor.c b/fs/squashfs/decompressor.c
index ac22fe73b0ad..e9034bf6e5ae 100644
--- a/fs/squashfs/decompressor.c
+++ b/fs/squashfs/decompressor.c
@@ -41,6 +41,12 @@ static const struct squashfs_decompressor squashfs_lzma_unsupported_comp_ops = {
         NULL, NULL, NULL, NULL, LZMA_COMPRESSION, "lzma", 0
 };
 
+#ifndef CONFIG_SQUASHFS_LZ4
+static const struct squashfs_decompressor squashfs_lz4_comp_ops = {
+        NULL, NULL, NULL, NULL, LZ4_COMPRESSION, "lz4", 0
+};
+#endif
+
 #ifndef CONFIG_SQUASHFS_LZO
 static const struct squashfs_decompressor squashfs_lzo_comp_ops = {
         NULL, NULL, NULL, NULL, LZO_COMPRESSION, "lzo", 0
@@ -65,6 +71,7 @@ static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
 
 static const struct squashfs_decompressor *decompressor[] = {
         &squashfs_zlib_comp_ops,
+        &squashfs_lz4_comp_ops,
         &squashfs_lzo_comp_ops,
         &squashfs_xz_comp_ops,
         &squashfs_lzma_unsupported_comp_ops,
diff --git a/fs/squashfs/decompressor.h b/fs/squashfs/decompressor.h
index af0985321808..a25713c031a5 100644
--- a/fs/squashfs/decompressor.h
+++ b/fs/squashfs/decompressor.h
@@ -46,6 +46,10 @@ static inline void *squashfs_comp_opts(struct squashfs_sb_info *msblk,
 extern const struct squashfs_decompressor squashfs_xz_comp_ops;
 #endif
 
+#ifdef CONFIG_SQUASHFS_LZ4
+extern const struct squashfs_decompressor squashfs_lz4_comp_ops;
+#endif
+
 #ifdef CONFIG_SQUASHFS_LZO
 extern const struct squashfs_decompressor squashfs_lzo_comp_ops;
 #endif
diff --git a/fs/squashfs/lz4_wrapper.c b/fs/squashfs/lz4_wrapper.c
new file mode 100644
index 000000000000..c31e2bc9c081
--- /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 4b2beda49498..506f4ba5b983 100644
--- 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;