[PATCH] ufs2 write: mount as rw

These series of patches add UFS2 write-support. UFS2 - is default file system
for recent versions of FreeBSD.

The main differences from UFS1 from write support point of view
are:
1)Not all inodes are allocated during formatation of disk.
2)All meta-data(pointer to data blocks) are 64bit(in UFS1 they
are 32bit).

So patch series consist of
1)make possible mount UFS2 in read-write mode
2)code to write ufs2 inodes and code to initialize inodes chunks.
3)work with 64bit meta-data

I made simple testing like create/deleting/writing/reading/truncating, also I
ran fsx-linux and untar and build kernel on UFS1 and UFS2, after that FreeBSD
fsck do not find any errors in fs.

This patch makes possible to mount ufs2 "rw", and updates UFS2 documentation:
remove note about bug(it fixed by reallocate blocks on the fly patch) and add
me in the list of people who want receive bug reports.

Signed-off-by: Evgeniy Dushistov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/filesystems/ufs.txt

···
 		supported as read-write
 
 	ufs2    used in FreeBSD 5.x
-		supported as read-only
+		supported as read-write
 
 	5xbsd	synonym for ufs2
 
···
 POSSIBLE PROBLEMS
 =================
 
-There is still bug in reallocation of fragment, in file fs/ufs/balloc.c, 
-line 364. But it seems working on current buffer cache configuration.
+See next section, if you have any.
 
 
 BUG REPORTS
 ===========
 
-Any ufs bug report you can send to [e-mail] (do not send 
-partition tables bug reports.)
+Any ufs bug report you can send to [e-mail] or
+to [e-mail] (do not send partition tables bug reports).

fs/ufs/super.c

···
  * UFS2 (of FreeBSD 5.x) support added by
  * Niraj Kumar <[e-mail]>, Jan 2004
  *
+ * UFS2 write support added by
+ * Evgeniy Dushistov <[e-mail]>, 2007
  */
 
 
···
 		uspi->s_sbsize = super_block_size = 1536;
 		uspi->s_sbbase =  0;
 		flags |= UFS_TYPE_UFS2 | UFS_DE_44BSD | UFS_UID_44BSD | UFS_ST_44BSD | UFS_CG_44BSD;
-		if (!(sb->s_flags & MS_RDONLY)) {
-			printk(KERN_INFO "ufstype=ufs2 is supported read-only\n");
-			sb->s_flags |= MS_RDONLY;
- 		}
 		break;
 		
 	case UFS_MOUNT_UFSTYPE_SUN:
···
 #else
 		if (ufstype != UFS_MOUNT_UFSTYPE_SUN && 
 		    ufstype != UFS_MOUNT_UFSTYPE_44BSD &&
-		    ufstype != UFS_MOUNT_UFSTYPE_SUNx86) {
+		    ufstype != UFS_MOUNT_UFSTYPE_SUNx86 &&
+		    ufstype != UFS_MOUNT_UFSTYPE_UFS2) {
 			printk("this ufstype is read-only supported\n");
 			return -EINVAL;
 		}