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SubjectRe: [PATCH 1/2 ] Add support LZO in cramfs
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The function pointer cramfs_uncompress_block is added inside the
cramfs_sb_info struct, so each mountpoint has its own
cramfs_uncompress_block depends on compression type.

I did some test, and verified multiple cramfs images mounted
successfully regardless of compression(either ZLIB or LZO).

Here is the patch.

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 2007-10-30 17:15:34.000000000 -0700
@@ -274,7 +274,17 @@
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) {
+ sbi->cramfs_uncompress_block = &cramfs_uncompress_block_lzo;
+ printk("cramfs: LZO compression\n");
+ }
+ else {
+ sbi->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");
@@ -486,7 +496,7 @@
printk(KERN_ERR "cramfs: bad compressed blocksize %u\n", compr_len);
else {
mutex_lock(&read_mutex);
- bytes_filled = cramfs_uncompress_block(pgdata,
+ bytes_filled = ((struct cramfs_sb_info *)(sb->s_fs_info))->cramfs_uncompress_block(pgdata,
PAGE_CACHE_SIZE,
cramfs_read(sb, start_offset, compr_len),
compr_len);
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
diff -Naur linux-2.6.23/include/linux/cramfs_fs_sb.h linux-2.6.23_cramfs_lzo/include/linux/cramfs_fs_sb.h
--- linux-2.6.23/include/linux/cramfs_fs_sb.h 2007-10-09 13:31:38.000000000 -0700
+++ linux-2.6.23_cramfs_lzo/include/linux/cramfs_fs_sb.h 2007-10-30 17:17:19.000000000 -0700
@@ -10,6 +10,8 @@
unsigned long blocks;
unsigned long files;
unsigned long flags;
+ /* function pointer to uncompress block */
+ int (* cramfs_uncompress_block) (void *dst, int dstlen, void *src, int srclen);
};

static inline struct cramfs_sb_info *CRAMFS_SB(struct super_block *sb)

On Mon, 2007-10-29 at 11:45 -0700, vince kim wrote:
> Thanks for your comment.
> I can't hardly imagine there would be a lot of cases to mount two
> different images with different compression, but if they did, then they
> would not work at the same time.
>
> For modular decompression, it would be out of my scope to modularize lzo
> or zlib. I will think about anyway.
>
> I used Evolution to submit patch, and it word-wrapped the patch.
>
> This must be clean.
>
> 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
>
>
>
>
> On Sat, 2007-10-27 at 13:09 +0400, Michael Tokarev wrote:
> > vince kim wrote:
> > > This is a kernel patch to add support LZO compression in cramfs.
> > []
> > > --- 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);
> >
> > Shouldn't this pointer be mountpoint-specific? I mean,
> > if I've two cramfs images, one using zlib and another
> > using lzo, the two will not work at the same time.
> >
> > []
> > > --- 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
> >
> > Hmm. How about using modular decompressor? I mean,
> > it isn't really necessary for a given config to handle
> > both lzo- and zlib-compressed cramfs images, only one
> > may be needed, so the other compression library becomes
> > a useless dependency. This is especially important for
> > embedded environments where memory/disk space is limited.
> > Since you're using a pointer-to-function anyway, it can
> > be done fully dynamically, by requesting a module to de-
> > compress the thing at runtime. Pretty much like it's
> > done f.e. in crypto/ipsec layer currently.
> >
> > By the way, your patch is word-wrapped.
> >
> > /mjt
-
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