Squashfs: add XZ compression support

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

This patch adds the XZ decompressor wrapper code.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>

2 files changed, 154 insertions, 0 deletions

diff --git a/fs/squashfs/squashfs_fs.h b/fs/squashfs/squashfs_fs.h
index c5137fc9ab1..39533feffd6 100644
--- a/fs/squashfs/squashfs_fs.h
+++ b/fs/squashfs/squashfs_fs.h
@@ -238,6 +238,7 @@ struct meta_index {
 #define ZLIB_COMPRESSION        1
 #define LZMA_COMPRESSION        2
 #define LZO_COMPRESSION         3
+#define XZ_COMPRESSION          4
 
 struct squashfs_super_block {
         __le32                  s_magic;
diff --git a/fs/squashfs/xz_wrapper.c b/fs/squashfs/xz_wrapper.c
new file mode 100644
index 00000000000..856756ca5ee
--- /dev/null
+++ b/fs/squashfs/xz_wrapper.c
@@ -0,0 +1,153 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
+ * Phillip Lougher <phillip@lougher.demon.co.uk>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2,
+ * or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * xz_wrapper.c
+ */
+
+
+#include <linux/mutex.h>
+#include <linux/buffer_head.h>
+#include <linux/slab.h>
+#include <linux/xz.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "squashfs.h"
+#include "decompressor.h"
+
+struct squashfs_xz {
+        struct xz_dec *state;
+        struct xz_buf buf;
+};
+
+static void *squashfs_xz_init(struct squashfs_sb_info *msblk)
+{
+        int block_size = max_t(int, msblk->block_size, SQUASHFS_METADATA_SIZE);
+
+        struct squashfs_xz *stream = kmalloc(sizeof(*stream), GFP_KERNEL);
+        if (stream == NULL)
+                goto failed;
+
+        stream->state = xz_dec_init(XZ_PREALLOC, block_size);
+        if (stream->state == NULL)
+                goto failed;
+
+        return stream;
+
+failed:
+        ERROR("Failed to allocate xz workspace\n");
+        kfree(stream);
+        return NULL;
+}
+
+
+static void squashfs_xz_free(void *strm)
+{
+        struct squashfs_xz *stream = strm;
+
+        if (stream) {
+                xz_dec_end(stream->state);
+                kfree(stream);
+        }
+}
+
+
+static int squashfs_xz_uncompress(struct squashfs_sb_info *msblk, void **buffer,
+        struct buffer_head **bh, int b, int offset, int length, int srclength,
+        int pages)
+{
+        enum xz_ret xz_err;
+        int avail, total = 0, k = 0, page = 0;
+        struct squashfs_xz *stream = msblk->stream;
+
+        mutex_lock(&msblk->read_data_mutex);
+
+        xz_dec_reset(stream->state);
+        stream->buf.in_pos = 0;
+        stream->buf.in_size = 0;
+        stream->buf.out_pos = 0;
+        stream->buf.out_size = PAGE_CACHE_SIZE;
+        stream->buf.out = buffer[page++];
+
+        do {
+                if (stream->buf.in_pos == stream->buf.in_size && k < b) {
+                        avail = min(length, msblk->devblksize - offset);
+                        length -= avail;
+                        wait_on_buffer(bh[k]);
+                        if (!buffer_uptodate(bh[k]))
+                                goto release_mutex;
+
+                        if (avail == 0) {
+                                offset = 0;
+                                put_bh(bh[k++]);
+                                continue;
+                        }
+
+                        stream->buf.in = bh[k]->b_data + offset;
+                        stream->buf.in_size = avail;
+                        stream->buf.in_pos = 0;
+                        offset = 0;
+                }
+
+                if (stream->buf.out_pos == stream->buf.out_size
+                                                        && page < pages) {
+                        stream->buf.out = buffer[page++];
+                        stream->buf.out_pos = 0;
+                        total += PAGE_CACHE_SIZE;
+                }
+
+                xz_err = xz_dec_run(stream->state, &stream->buf);
+
+                if (stream->buf.in_pos == stream->buf.in_size && k < b)
+                        put_bh(bh[k++]);
+        } while (xz_err == XZ_OK);
+
+        if (xz_err != XZ_STREAM_END) {
+                ERROR("xz_dec_run error, data probably corrupt\n");
+                goto release_mutex;
+        }
+
+        if (k < b) {
+                ERROR("xz_uncompress error, input remaining\n");
+                goto release_mutex;
+        }
+
+        total += stream->buf.out_pos;
+        mutex_unlock(&msblk->read_data_mutex);
+        return total;
+
+release_mutex:
+        mutex_unlock(&msblk->read_data_mutex);
+
+        for (; k < b; k++)
+                put_bh(bh[k]);
+
+        return -EIO;
+}
+
+const struct squashfs_decompressor squashfs_xz_comp_ops = {
+        .init = squashfs_xz_init,
+        .free = squashfs_xz_free,
+        .decompress = squashfs_xz_uncompress,
+        .id = XZ_COMPRESSION,
+        .name = "xz",
+        .supported = 1
+};