This is a kernel patch to add support LZO compression in cramfs.
I used LZO kernel library patch done by Richard Purdie
[[email protected]], and my cramfs patch requires his LZO library
patch.
Richard's LZO kernel library patch can be found at:
http://lwn.net/Articles/238723/
This patch is generated against 2.6.23.
We had some performance gain with cramfs using LZO compression, but the
cramfs image size has been increased by around 10%.
So, if performance is higher priority, you could try this patch.
I will post separate patch for mkcramfs tool to generate cramfs image
using LZO compression.
Thanks,
Vince Kyong-jin Kim [[email protected]]
diff -Naur linux-2.6.23/fs/cramfs/inode.c
linux-2.6.23_cramfs_lzo/fs/cramfs/inode.c
--- linux-2.6.23/fs/cramfs/inode.c 2007-10-09 13:31:38.000000000
-0700
+++ linux-2.6.23_cramfs_lzo/fs/cramfs/inode.c 2007-10-26
14:35:59.000000000 -0700
@@ -31,6 +31,8 @@
static const struct inode_operations cramfs_dir_inode_operations;
static const struct file_operations cramfs_directory_operations;
static const struct address_space_operations cramfs_aops;
+/* function pointer to uncompress block */
+static int (* cramfs_uncompress_block) (void *dst, int dstlen, void
*src, int srclen);
static DEFINE_MUTEX(read_mutex);
@@ -274,7 +276,17 @@
printk(KERN_ERR "cramfs: unsupported filesystem features
\n");
goto out;
}
-
+
+ /* check flag to see if LZO compression is used */
+ if (super.flags & CRAMFS_FLAG_LZO_COMPRESSION) {
+ cramfs_uncompress_block = &cramfs_uncompress_block_lzo;
+ printk("cramfs: LZO compression\n");
+ }
+ else {
+ cramfs_uncompress_block = &cramfs_uncompress_block_zlib;
+ printk("cramfs: ZLIB compression\n");
+ }
+
/* Check that the root inode is in a sane state */
if (!S_ISDIR(super.root.mode)) {
printk(KERN_ERR "cramfs: root is not a directory\n");
diff -Naur linux-2.6.23/fs/cramfs/uncompress.c
linux-2.6.23_cramfs_lzo/fs/cramfs/uncompress.c
--- linux-2.6.23/fs/cramfs/uncompress.c 2007-10-09 13:31:38.000000000
-0700
+++ linux-2.6.23_cramfs_lzo/fs/cramfs/uncompress.c 2007-10-26
14:19: 01.000000000 -0700
@@ -20,12 +20,16 @@
#include <linux/vmalloc.h>
#include <linux/zlib.h>
#include <linux/cramfs_fs.h>
+#include <linux/lzo.h>
static z_stream stream;
static int initialized;
-/* Returns length of decompressed data. */
-int cramfs_uncompress_block(void *dst, int dstlen, void *src, int
srclen)
+/*
+ * uncompress with ZLIB
+ * Returns length of decompressed data.
+ */
+int cramfs_uncompress_block_zlib(void *dst, int dstlen, void *src, int
srclen)
{
int err;
@@ -48,7 +52,26 @@
return stream.total_out;
err:
- printk("Error %d while decompressing!\n", err);
+ printk("ZLIB Error %d while decompressing!\n", err);
+ printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
+ return 0;
+}
+
+/*
+ * uncompress with LZO
+ * Returns length of decompressed data.
+ */
+int cramfs_uncompress_block_lzo(void *dst, int dstlen, void *src, int
srclen)
+{
+ int err;
+
+ err = lzo1x_decompress_safe(src,srclen,dst,(unsigned int
*)&dstlen);
+ if (err != LZO_E_OK)
+ goto err;
+ return dstlen;
+
+err:
+ printk("LZO Error %d while decompressing!\n", err);
printk("%p(%d)->%p(%d)\n", src, srclen, dst, dstlen);
return 0;
}
diff -Naur linux-2.6.23/fs/Kconfig linux-2.6.23_cramfs_lzo/fs/Kconfig
--- linux-2.6.23/fs/Kconfig 2007-10-09 13:31:38.000000000 -0700
+++ linux-2.6.23_cramfs_lzo/fs/Kconfig 2007-10-26 14:19:01.000000000
-0700
@@ -1348,6 +1348,7 @@
tristate "Compressed ROM file system support (cramfs)"
depends on BLOCK
select ZLIB_INFLATE
+ select LZO_DECOMPRESS
help
Saying Y here includes support for CramFs (Compressed ROM File
System). CramFs is designed to be a simple, small, and
compressed
diff -Naur linux-2.6.23/include/linux/cramfs_fs.h
linux-2.6.23_cramfs_lzo/include/linux/cramfs_fs.h
--- linux-2.6.23/include/linux/cramfs_fs.h 2007-10-09
13:31:38.000000000 -0700
+++ linux-2.6.23_cramfs_lzo/include/linux/cramfs_fs.h 2007-10-26
14:19:01.000000000 -0700
@@ -73,6 +73,7 @@
#define CRAMFS_FLAG_HOLES 0x00000100 /* support for
holes */
#define CRAMFS_FLAG_WRONG_SIGNATURE 0x00000200 /* reserved */
#define CRAMFS_FLAG_SHIFTED_ROOT_OFFSET 0x00000400 /*
shifted root fs */
+#define CRAMFS_FLAG_LZO_COMPRESSION 0x00000800 /* LZO
compression is used */
/*
* Valid values in super.flags. Currently we refuse to mount
@@ -82,11 +83,16 @@
#define CRAMFS_SUPPORTED_FLAGS ( 0x000000ff \
| CRAMFS_FLAG_HOLES \
| CRAMFS_FLAG_WRONG_SIGNATURE \
- | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET )
+ | CRAMFS_FLAG_SHIFTED_ROOT_OFFSET \
+ | CRAMFS_FLAG_LZO_COMPRESSION )
+
+/* function pointer for uncompress function */
/* Uncompression interfaces to the underlying zlib */
-int cramfs_uncompress_block(void *dst, int dstlen, void *src, int
srclen);
+int cramfs_uncompress_block_zlib(void *dst, int dstlen, void *src, int
srclen);
int cramfs_uncompress_init(void);
void cramfs_uncompress_exit(void);
+/* Uncompression interfaces to the underlying lzo */
+int cramfs_uncompress_block_lzo(void *dst, int dstlen, void *src, int
srclen);
#endif
-
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