[PATCH] cramfs updates for 2.5.6-pre2

Documentation/filesystems/cramfs.txt
  - remove comment about ROM size limit
  - fix up magic
  - update location of tools

fs/cramfs/README
  - add note about sorted directory entries
  - mkcramfs compile-time DO_HOLES option replaced by run-time -z option
  - update tools section
  - add note about PAGE_CACHE_SIZE possibly changing on arm and ia64

fs/cramfs/inode.c
  - statfs->f_namelen = CRAMFS_MAXPATHLEN

include/linux/cramfs_fs.h
  - add CRAMFS_MAXPATHLEN (252)
  - clarify CRAMFS_SUPPORTED_FLAGS definition

scripts/cramfs
  - directory removed, the cramfs user-space tools are now located at
    <http://sourceforge.net/projects/cramfs/>.

Documentation/filesystems/cramfs.txt

@@ -10,7 +10,7 @@ diskspace than traditional filesystems.
 
 You can't write to a cramfs filesystem (making it compressible and
 compact also makes it _very_ hard to update on-the-fly), so you have to
-create the disk image with the "mkcramfs" utility in scripts/cramfs.
+create the disk image with the "mkcramfs" utility.
 
 
 Usage Notes
@@ -19,9 +19,7 @@ Usage Notes
 File sizes are limited to less than 16MB.
 
 Maximum filesystem size is a little over 256MB.  (The last file on the
-filesystem is allowed to extend past 256MB.)  (Comments in mkcramfs.c
-suggest that ROM sizes may be limited to 64MB, though that's not a
-limitation in cramfs code.)
+filesystem is allowed to extend past 256MB.)
 
 Only the low 8 bits of gid are stored.  The current version of
 mkcramfs simply truncates to 8 bits, which is a potential security
@@ -48,18 +46,28 @@ mind the filesystem becoming unreadable to future kernels.
 
 
 For /usr/share/magic
-------------------
+--------------------
 
-0	long	0x28cd3d45	Linux cramfs
->4	long	x		size %d
->8	long	x		flags 0x%x
->12	long	x		future 0x%x
+0	ulelong	0x28cd3d45	Linux cramfs offset 0
+>4	ulelong	x		size %d
+>8	ulelong	x		flags 0x%x
+>12	ulelong	x		future 0x%x
 >16	string	>\0		signature "%.16s"
->32	long	x		fsid.crc 0x%x
->36	long	x		fsid.edition %d
->40	long	x		fsid.blocks %d
->44	long	x		fsid.files %d
+>32	ulelong	x		fsid.crc 0x%x
+>36	ulelong	x		fsid.edition %d
+>40	ulelong	x		fsid.blocks %d
+>44	ulelong	x		fsid.files %d
 >48	string	>\0		name "%.16s"
+512	ulelong	0x28cd3d45	Linux cramfs offset 512
+>516	ulelong	x		size %d
+>520	ulelong	x		flags 0x%x
+>524	ulelong	x		future 0x%x
+>528	string	>\0		signature "%.16s"
+>544	ulelong	x		fsid.crc 0x%x
+>548	ulelong	x		fsid.edition %d
+>552	ulelong	x		fsid.blocks %d
+>556	ulelong	x		fsid.files %d
+>560	string	>\0		name "%.16s"
 
 
 Hacker Notes

fs/cramfs/README

@@ -6,8 +6,8 @@ a bit looser, e.g. it doesn't care if the <file_data> items are
 swapped around (though it does care that directory entries (inodes) in
 a given directory are contiguous, as this is used by readdir).
 
-All data is in host-endian format; neither mkcramfs nor the kernel
-ever do swabbing.  (See section `Block Size' below.)
+All data is currently in host-endian format; neither mkcramfs nor the
+kernel ever do swabbing.  (See section `Block Size' below.)
 
 <filesystem>:
 	<superblock>
@@ -29,6 +29,10 @@ same order as `ls -AUR' (but without the /^\..*:$/ directory header
 lines); put another way, the same order as `find -type d -exec
 ls -AU1 {} \;'.
 
+Beginning in 2.4.7, directory entries are sorted.  This optimization
+allows cramfs_lookup to return more quickly when a filename does not
+exist, speeds up user-space directory sorts, etc.
+
 <data>:
 	One <file_data> for each file that's either a symlink or a
 	 regular file of non-zero st_size.
@@ -63,17 +67,15 @@ Holes
 This kernel supports cramfs holes (i.e. [efficient representation of]
 blocks in uncompressed data consisting entirely of NUL bytes), but by
 default mkcramfs doesn't test for & create holes, since cramfs in
-kernels up to at least 2.3.39 didn't support holes.  Compile mkcramfs
-with -DDO_HOLES if you want it to create files that can have holes in
-them.
+kernels up to at least 2.3.39 didn't support holes.  Run mkcramfs
+with -z if you want it to create files that can have holes in them.
 
 
 Tools
 -----
 
-If you're hacking on cramfs, you might find useful some tools for
-testing cramfs at <http://cvs.bofh.asn.au/cramfs/>, including a
-rudimentary fsck for cramfs.
+The cramfs user-space tools, including mkcramfs and cramfsck, are
+located at <http://sourceforge.net/projects/cramfs/>.
 
 
 Future Development
@@ -103,8 +105,8 @@ require the least amount of change: just change `#define
 PAGE_CACHE_SIZE (4096)' to `#include <asm/page.h>'.  The disadvantage
 is that the generated cramfs cannot always be shared between different
 kernels, not even necessarily kernels of the same architecture if
-PAGE_CACHE_SIZE is subject to change between kernel versions.
-
+PAGE_CACHE_SIZE is subject to change between kernel versions
+(currently possible with arm and ia64).
 
 The remaining options try to make cramfs more sharable.
 

fs/cramfs/inode.c

@@ -266,7 +266,7 @@ static int cramfs_statfs(struct super_block *sb, struct statfs *buf)
 	buf->f_bavail = 0;
 	buf->f_files = sb->CRAMFS_SB_FILES;
 	buf->f_ffree = 0;
-	buf->f_namelen = 255;
+	buf->f_namelen = CRAMFS_MAXPATHLEN;
 	return 0;
 }
 
@@ -476,4 +476,3 @@ static void __exit exit_cramfs_fs(void)
 module_init(init_cramfs_fs)
 module_exit(exit_cramfs_fs)
 MODULE_LICENSE("GPL");
-

include/linux/cramfs_fs.h

@@ -23,6 +23,12 @@ typedef unsigned int u32;
 #define CRAMFS_NAMELEN_WIDTH 6
 #define CRAMFS_OFFSET_WIDTH 26
 
+/*
+ * Since inode.namelen is a unsigned 6-bit number, the maximum cramfs
+ * path length is 63 << 2 = 252.
+ */
+#define CRAMFS_MAXPATHLEN (((1 << CRAMFS_NAMELEN_WIDTH) - 1) << 2)
+
 /*
  * Reasonably terse representation of the inode data.
  */
@@ -54,12 +60,12 @@ struct cramfs_info {
 struct cramfs_super {
 	u32 magic;			/* 0x28cd3d45 - random number */
 	u32 size;			/* length in bytes */
-	u32 flags;		/* 0 */
-	u32 future;		/* 0 */
+	u32 flags;			/* feature flags */
+	u32 future;			/* reserved for future use */
 	u8 signature[16];		/* "Compressed ROMFS" */
 	struct cramfs_info fsid;	/* unique filesystem info */
 	u8 name[16];			/* user-defined name */
-	struct cramfs_inode root;	/* Root inode data */
+	struct cramfs_inode root;	/* root inode data */
 };
 
 /*
@@ -79,7 +85,10 @@ struct cramfs_super {
  * if (flags & ~CRAMFS_SUPPORTED_FLAGS).  Maybe that should be
  * changed to test super.future instead.
  */
-#define CRAMFS_SUPPORTED_FLAGS (0x7ff)
+#define CRAMFS_SUPPORTED_FLAGS	( 0x000000ff \
+				| CRAMFS_FLAG_HOLES \
+				| CRAMFS_FLAG_WRONG_SIGNATURE \
+				| CRAMFS_FLAG_SHIFTED_ROOT_OFFSET )
 
 /* Uncompression interfaces to the underlying zlib */
 int cramfs_uncompress_block(void *dst, int dstlen, void *src, int srclen);

scripts/cramfs/GNUmakefile

-CC = gcc
-CFLAGS = -W -Wall -O2 -g
-CPPFLAGS = -I../../include
-LDLIBS = -lz
-PROGS = mkcramfs cramfsck
-
-all: $(PROGS)
-
-distclean clean:
-	rm -f $(PROGS)
-
-.PHONY: all clean