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Subject[PATCH 3/9] Squashfs: add a decompressor framework
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Date

This adds a decompressor framework which allows multiple compression
algorithms to be cleanly supported.

Also update zlib wrapper and other code to use the new framework.

Signed-off-by: Phillip Lougher <phillip@lougher.demon.co.uk>
---
fs/squashfs/Makefile | 2 +-
fs/squashfs/block.c | 6 ++--
fs/squashfs/decompressor.c | 58 ++++++++++++++++++++++++++++++++++++++++++
fs/squashfs/decompressor.h | 55 +++++++++++++++++++++++++++++++++++++++
fs/squashfs/squashfs.h | 14 +++++-----
fs/squashfs/squashfs_fs_sb.h | 41 +++++++++++++++--------------
fs/squashfs/super.c | 45 ++++++++++++++++++-------------
fs/squashfs/zlib_wrapper.c | 17 ++++++++++--
8 files changed, 185 insertions(+), 53 deletions(-)
create mode 100644 fs/squashfs/decompressor.c
create mode 100644 fs/squashfs/decompressor.h

diff --git a/fs/squashfs/Makefile b/fs/squashfs/Makefile
index a397e6f..df8a19e 100644
--- a/fs/squashfs/Makefile
+++ b/fs/squashfs/Makefile
@@ -4,4 +4,4 @@

obj-$(CONFIG_SQUASHFS) += squashfs.o
squashfs-y += block.o cache.o dir.o export.o file.o fragment.o id.o inode.o
-squashfs-y += namei.o super.o symlink.o zlib_wrapper.o
+squashfs-y += namei.o super.o symlink.o zlib_wrapper.o decompressor.o
diff --git a/fs/squashfs/block.c b/fs/squashfs/block.c
index baf7624..6f9914d 100644
--- a/fs/squashfs/block.c
+++ b/fs/squashfs/block.c
@@ -36,7 +36,7 @@
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
-
+#include "decompressor.h"
/*
* Read the metadata block length, this is stored in the first two
* bytes of the metadata block.
@@ -151,8 +151,8 @@ int squashfs_read_data(struct super_block *sb, void **buffer, u64 index,
}

if (compressed) {
- length = zlib_uncompress(msblk, buffer, bh, b, offset, length,
- srclength, pages);
+ length = squashfs_decompress(msblk, buffer, bh, b, offset,
+ length, srclength, pages);
if (length < 0)
goto read_failure;
} else {
diff --git a/fs/squashfs/decompressor.c b/fs/squashfs/decompressor.c
new file mode 100644
index 0000000..0072ccd
--- /dev/null
+++ b/fs/squashfs/decompressor.c
@@ -0,0 +1,58 @@
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+ * 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.
+ *
+ * decompressor.c
+ */
+
+#include <linux/types.h>
+#include <linux/mutex.h>
+#include <linux/buffer_head.h>
+
+#include "squashfs_fs.h"
+#include "squashfs_fs_sb.h"
+#include "squashfs_fs_i.h"
+#include "decompressor.h"
+#include "squashfs.h"
+
+/*
+ * This file (and decompressor.h) implements a decompressor framework for
+ * Squashfs, allowing multiple decompressors to be easily supported
+ */
+
+static const struct squashfs_decompressor squashfs_unknown_comp_ops = {
+ NULL, NULL, NULL, 0, "unknown", 0
+};
+
+static const struct squashfs_decompressor *decompressor[] = {
+ &squashfs_zlib_comp_ops,
+ &squashfs_unknown_comp_ops
+};
+
+
+const struct squashfs_decompressor *squashfs_lookup_decompressor(int id)
+{
+ int i;
+
+ for (i = 0; decompressor[i]->id; i++)
+ if (id == decompressor[i]->id)
+ break;
+
+ return decompressor[i];
+}
diff --git a/fs/squashfs/decompressor.h b/fs/squashfs/decompressor.h
new file mode 100644
index 0000000..778760c
--- /dev/null
+++ b/fs/squashfs/decompressor.h
@@ -0,0 +1,55 @@
+#ifndef DECOMPRESSOR_H
+#define DECOMPRESSOR_H
+/*
+ * Squashfs - a compressed read only filesystem for Linux
+ *
+ * Copyright (c) 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
+ * 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.
+ *
+ * decompressor.h
+ */
+
+struct squashfs_decompressor {
+ void *(*init)(void);
+ void (*free)(void *);
+ int (*decompress)(struct squashfs_sb_info *, void **,
+ struct buffer_head **, int, int, int, int, int);
+ int id;
+ char *name;
+ int supported;
+};
+
+static inline void *squashfs_decompressor_init(struct squashfs_sb_info *msblk)
+{
+ return msblk->decompressor->init();
+}
+
+static inline void squashfs_decompressor_free(struct squashfs_sb_info *msblk,
+ void *s)
+{
+ if (msblk->decompressor)
+ msblk->decompressor->free(s);
+}
+
+static inline int squashfs_decompress(struct squashfs_sb_info *msblk,
+ void **buffer, struct buffer_head **bh, int b, int offset, int length,
+ int srclength, int pages)
+{
+ return msblk->decompressor->decompress(msblk, buffer, bh, b, offset,
+ length, srclength, pages);
+}
+#endif
diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
index b3eaf87..fe2587a 100644
--- a/fs/squashfs/squashfs.h
+++ b/fs/squashfs/squashfs.h
@@ -51,6 +51,9 @@ extern struct squashfs_cache_entry *squashfs_get_datablock(struct super_block *,
u64, int);
extern int squashfs_read_table(struct super_block *, void *, u64, int);

+/* decompressor.c */
+extern const struct squashfs_decompressor *squashfs_lookup_decompressor(int);
+
/* export.c */
extern __le64 *squashfs_read_inode_lookup_table(struct super_block *, u64,
unsigned int);
@@ -70,14 +73,8 @@ extern struct inode *squashfs_iget(struct super_block *, long long,
unsigned int);
extern int squashfs_read_inode(struct inode *, long long);

-/* zlib_wrapper.c */
-extern void *zlib_init(void);
-extern void zlib_free(void *);
-extern int zlib_uncompress(struct squashfs_sb_info *, void **,
- struct buffer_head **, int, int, int, int, int);
-
/*
- * Inodes and files operations
+ * Inodes, files and decompressor operations
*/

/* dir.c */
@@ -94,3 +91,6 @@ extern const struct inode_operations squashfs_dir_inode_ops;

/* symlink.c */
extern const struct address_space_operations squashfs_symlink_aops;
+
+/* zlib_wrapper.c */
+extern const struct squashfs_decompressor squashfs_zlib_comp_ops;
diff --git a/fs/squashfs/squashfs_fs_sb.h b/fs/squashfs/squashfs_fs_sb.h
index 23a67fa..7533350 100644
--- a/fs/squashfs/squashfs_fs_sb.h
+++ b/fs/squashfs/squashfs_fs_sb.h
@@ -52,25 +52,26 @@ struct squashfs_cache_entry {
};

struct squashfs_sb_info {
- int devblksize;
- int devblksize_log2;
- struct squashfs_cache *block_cache;
- struct squashfs_cache *fragment_cache;
- struct squashfs_cache *read_page;
- int next_meta_index;
- __le64 *id_table;
- __le64 *fragment_index;
- unsigned int *fragment_index_2;
- struct mutex read_data_mutex;
- struct mutex meta_index_mutex;
- struct meta_index *meta_index;
- void *stream;
- __le64 *inode_lookup_table;
- u64 inode_table;
- u64 directory_table;
- unsigned int block_size;
- unsigned short block_log;
- long long bytes_used;
- unsigned int inodes;
+ const struct squashfs_decompressor *decompressor;
+ int devblksize;
+ int devblksize_log2;
+ struct squashfs_cache *block_cache;
+ struct squashfs_cache *fragment_cache;
+ struct squashfs_cache *read_page;
+ int next_meta_index;
+ __le64 *id_table;
+ __le64 *fragment_index;
+ unsigned int *fragment_index_2;
+ struct mutex read_data_mutex;
+ struct mutex meta_index_mutex;
+ struct meta_index *meta_index;
+ void *stream;
+ __le64 *inode_lookup_table;
+ u64 inode_table;
+ u64 directory_table;
+ unsigned int block_size;
+ unsigned short block_log;
+ long long bytes_used;
+ unsigned int inodes;
};
#endif
diff --git a/fs/squashfs/super.c b/fs/squashfs/super.c
index 6c3429b..3550aec 100644
--- a/fs/squashfs/super.c
+++ b/fs/squashfs/super.c
@@ -41,27 +41,35 @@
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
+#include "decompressor.h"

static struct file_system_type squashfs_fs_type;
static const struct super_operations squashfs_super_ops;

-static int supported_squashfs_filesystem(short major, short minor, short comp)
+static const struct squashfs_decompressor *supported_squashfs_filesystem(short
+ major, short minor, short id)
{
+ const struct squashfs_decompressor *decompressor;
+
if (major < SQUASHFS_MAJOR) {
ERROR("Major/Minor mismatch, older Squashfs %d.%d "
"filesystems are unsupported\n", major, minor);
- return -EINVAL;
+ return NULL;
} else if (major > SQUASHFS_MAJOR || minor > SQUASHFS_MINOR) {
ERROR("Major/Minor mismatch, trying to mount newer "
"%d.%d filesystem\n", major, minor);
ERROR("Please update your kernel\n");
- return -EINVAL;
+ return NULL;
}

- if (comp != ZLIB_COMPRESSION)
- return -EINVAL;
+ decompressor = squashfs_lookup_decompressor(id);
+ if (!decompressor->supported) {
+ ERROR("Filesystem uses \"%s\" compression. This is not "
+ "supported\n", decompressor->name);
+ return NULL;
+ }

- return 0;
+ return decompressor;
}


@@ -86,10 +94,6 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
}
msblk = sb->s_fs_info;

- msblk->stream = zlib_init();
- if (msblk->stream == NULL)
- goto failure;
-
sblk = kzalloc(sizeof(*sblk), GFP_KERNEL);
if (sblk == NULL) {
ERROR("Failed to allocate squashfs_super_block\n");
@@ -116,25 +120,25 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)
goto failed_mount;
}

+ err = -EINVAL;
+
/* Check it is a SQUASHFS superblock */
sb->s_magic = le32_to_cpu(sblk->s_magic);
if (sb->s_magic != SQUASHFS_MAGIC) {
if (!silent)
ERROR("Can't find a SQUASHFS superblock on %s\n",
bdevname(sb->s_bdev, b));
- err = -EINVAL;
goto failed_mount;
}

- /* Check the MAJOR & MINOR versions and compression type */
- err = supported_squashfs_filesystem(le16_to_cpu(sblk->s_major),
+ /* Check the MAJOR & MINOR versions and lookup compression type */
+ msblk->decompressor = supported_squashfs_filesystem(
+ le16_to_cpu(sblk->s_major),
le16_to_cpu(sblk->s_minor),
le16_to_cpu(sblk->compression));
- if (err < 0)
+ if (msblk->decompressor == NULL)
goto failed_mount;

- err = -EINVAL;
-
/*
* Check if there's xattrs in the filesystem. These are not
* supported in this version, so warn that they will be ignored.
@@ -201,6 +205,10 @@ static int squashfs_fill_super(struct super_block *sb, void *data, int silent)

err = -ENOMEM;

+ msblk->stream = squashfs_decompressor_init(msblk);
+ if (msblk->stream == NULL)
+ goto failed_mount;
+
msblk->block_cache = squashfs_cache_init("metadata",
SQUASHFS_CACHED_BLKS, SQUASHFS_METADATA_SIZE);
if (msblk->block_cache == NULL)
@@ -288,7 +296,7 @@ failed_mount:
squashfs_cache_delete(msblk->block_cache);
squashfs_cache_delete(msblk->fragment_cache);
squashfs_cache_delete(msblk->read_page);
- zlib_free(msblk->stream);
+ squashfs_decompressor_free(msblk, msblk->stream);
kfree(msblk->inode_lookup_table);
kfree(msblk->fragment_index);
kfree(msblk->id_table);
@@ -298,7 +306,6 @@ failed_mount:
return err;

failure:
- zlib_free(msblk->stream);
kfree(sb->s_fs_info);
sb->s_fs_info = NULL;
return -ENOMEM;
@@ -342,7 +349,7 @@ static void squashfs_put_super(struct super_block *sb)
squashfs_cache_delete(sbi->block_cache);
squashfs_cache_delete(sbi->fragment_cache);
squashfs_cache_delete(sbi->read_page);
- zlib_free(sbi->stream);
+ squashfs_decompressor_free(sbi, sbi->stream);
kfree(sbi->id_table);
kfree(sbi->fragment_index);
kfree(sbi->meta_index);
diff --git a/fs/squashfs/zlib_wrapper.c b/fs/squashfs/zlib_wrapper.c
index 8ebbbc7..381768c 100644
--- a/fs/squashfs/zlib_wrapper.c
+++ b/fs/squashfs/zlib_wrapper.c
@@ -30,8 +30,9 @@
#include "squashfs_fs_sb.h"
#include "squashfs_fs_i.h"
#include "squashfs.h"
+#include "decompressor.h"

-void *zlib_init()
+static void *zlib_init(void)
{
z_stream *stream = kmalloc(sizeof(z_stream), GFP_KERNEL);
if (stream == NULL)
@@ -50,7 +51,7 @@ failed:
}


-void zlib_free(void *strm)
+static void zlib_free(void *strm)
{
z_stream *stream = strm;

@@ -60,7 +61,7 @@ void zlib_free(void *strm)
}


-int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
+static int zlib_uncompress(struct squashfs_sb_info *msblk, void **buffer,
struct buffer_head **bh, int b, int offset, int length, int srclength,
int pages)
{
@@ -137,3 +138,13 @@ release_mutex:

return -EIO;
}
+
+const struct squashfs_decompressor squashfs_zlib_comp_ops = {
+ .init = zlib_init,
+ .free = zlib_free,
+ .decompress = zlib_uncompress,
+ .id = ZLIB_COMPRESSION,
+ .name = "zlib",
+ .supported = 1
+};
+
--
1.6.3.3


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