>Number:         2779
>Category:       kern
>Synopsis:       SVR4-emulation statvfs is wrong; makes WABI break (easy fix)
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    kern-bug-people (Kernel Bug People)
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Sep 24 19:50:01 1996
>Last-Modified:
>Originator:     Aaron Brown
>Organization:
Harvard University Computer Science
>Release:        1.2A, 20 September 1996
>Environment:
	Sun SPARCstation 20, fully -current world as of 9/20/96, running
	SVR4 emulation with libs from Solaris 2.4
System: NetBSD abrown-2 1.2A NetBSD 1.2A (ABROWN) #2: Tue Sep 24 17:08:40 EDT 1996 abrown@abrown-2:/usr/src/sys/arch/sparc/compile/ABROWN sparc


>Description:
	The SVR4 emulation code for statvfs returns the BSD fragment size
	as the file system's "preferred FS block size" (solaris manpage) and
	the fragment size/8 as the fundamental FS block size. It then reports
	all the other stats in terms of the fragment size. This is wrong:
	according to the Solaris manpage, all of the other disk stats 
	are in terms of the fundamental block size (f_frsize). Thus the 
	current mapping from BSD to SVR4 statfs is:

		BSD			SVR4
		---			----
		f_bsize			f_bsize
		f_bsize/8		f_frsize

	whereas it should be

		f_iosize		f_bsize (preferred I/O size)
		f_bsize			f_frsize (fragment size)

	The upshot of this bug is that programs like WABI think that
	the disk is full, since on a 8K/1K filesystem, it sees the 
	number of free bytes as f_bfree*128, as opposed to the correct
	f_bfree*1024.

	The fix is trivial and is included below, although I'm not sure
	that the BSD "optimal transfer block size" is always the FFS 
	block size: thus the XXX.
>How-To-Repeat:
	Install WABI 2.1. Try to install MS windows under WABI. Most likely
	it will tell you that you don't have enough space (unless you have
	a huge disk).
>Fix:
	Apply this patch:

Index: svr4_misc.c
===================================================================
RCS file: /cvsroot/src/sys/compat/svr4/svr4_misc.c,v
retrieving revision 1.39
diff -c -r1.39 svr4_misc.c
*** svr4_misc.c	1996/09/03 03:12:38	1.39
--- svr4_misc.c	1996/09/24 21:18:12
***************
*** 1103,1110 ****
  	const struct statfs *bfs;
  	struct svr4_statvfs *sfs;
  {
! 	sfs->f_bsize = bfs->f_bsize;
! 	sfs->f_frsize = bfs->f_bsize / 8; /* XXX */
  	sfs->f_blocks = bfs->f_blocks;
  	sfs->f_bfree = bfs->f_bfree;
  	sfs->f_bavail = bfs->f_bavail;
--- 1103,1110 ----
  	const struct statfs *bfs;
  	struct svr4_statvfs *sfs;
  {
! 	sfs->f_bsize = bfs->f_iosize; /* XXX */
! 	sfs->f_frsize = bfs->f_bsize;
  	sfs->f_blocks = bfs->f_blocks;
  	sfs->f_bfree = bfs->f_bfree;
  	sfs->f_bavail = bfs->f_bavail;
>Audit-Trail:
>Unformatted: