Subject: Fsck may not convert filesystem types correctly
Index: etc/fsck/setup.c 4.3BSD-tahoe

Description:
	Note: this bug report applies to the 4.3BSD-tahoe release ONLY.

	When converting between old and new filesystem formats, fsck 
	fails to recalculate the cylinder group size. If the size 
	increases, the filesystem will panic with a consistency
	check when trying to allocate blocks for a file.

Repeat-By:
	Create a new filesystem with eight cylinders per group.
	Convert it from new to old format and notice that dumpfs
	still reports it as having a cgsize of 1024 when it should 
	have a cgsize of 2048. Mount the filesystem and try to copy
	data into it. The system will eventually panic.

Fix:
	*** setup.5.19	Tue Jun 27 17:11:52 1989
	--- setup.5.20	Tue Jun 27 17:11:45 1989
	***************
	*** 5,11 ****
	   */
	  
	  #ifndef lint
	! static char sccsid[] = "@(#)setup.c	5.19 (Berkeley) 5/7/88";
	  #endif not lint
	  
	  #define DKTYPENAMES
	--- 5,11 ----
	   */
	  
	  #ifndef lint
	! static char sccsid[] = "@(#)setup.c	5.20 (Berkeley) 6/26/89";
	  #endif not lint
	  
	  #define DKTYPENAMES
	***************
	*** 24,29 ****
	--- 24,42 ----
	  #define altsblock (*asblk.b_un.b_fs)
	  #define POWEROF2(num)	(((num) & ((num) - 1)) == 0)
	  
	+ /*
	+  * The size of a cylinder group is calculated by CGSIZE. The maximum size
	+  * is limited by the fact that cylinder groups are at most one block.
	+  * Its size is derived from the size of the maps maintained in the 
	+  * cylinder group and the (struct cg) size.
	+  */
	+ #define CGSIZE(fs) \
	+     /* base cg */	(sizeof(struct cg) + \
	+     /* blktot size */	(fs)->fs_cpg * sizeof(long) + \
	+     /* blks size */	(fs)->fs_cpg * (fs)->fs_nrpos * sizeof(short) + \
	+     /* inode map */	howmany((fs)->fs_ipg, NBBY) + \
	+     /* block map */	howmany((fs)->fs_cpg * (fs)->fs_spc / NSPF(fs), NBBY))
	+ 
	  char	*calloc();
	  char	*index();
	  
	***************
	*** 166,171 ****
	--- 179,186 ----
				    (char *)(&sblock.fs_link);
				sblock.fs_rotbloff = &sblock.fs_space[0] -
				    (u_char *)(&sblock.fs_link);
	+ 			sblock.fs_cgsize =
	+ 				fragroundup(&sblock, CGSIZE(&sblock));
				/*
				 * Planning now for future expansion.
				 */
	***************
	*** 199,204 ****
	--- 214,221 ----
				else if (!reply("CONVERT TO OLD FILE SYSTEM FORMAT"))
					return(0);
				sblock.fs_postblformat = FS_42POSTBLFMT;
	+ 			sblock.fs_cgsize = fragroundup(&sblock,
	+ 			    sizeof(struct ocg) + howmany(sblock.fs_fpg, NBBY));
				sbdirty();
				dirty(&asblk);
			} else {