bin/107692: commit references a PR

[dfilter service]

The following reply was made to PR bin/107692; it has been noted by GNATS.

From: dfilter at FreeBSD.ORG (dfilter service)
To: bug-followup at FreeBSD.org
Cc:  
Subject: Re: bin/107692: commit references a PR
Date: Fri, 24 Sep 2010 19:09:02 +0000 (UTC)

 Author: mckusick
 Date: Fri Sep 24 19:08:56 2010
 New Revision: 213119
 URL: http://svn.freebsd.org/changeset/base/213119
 
 Log:
   Reported problem:
   Large (60GB) filesystems created using "newfs -U -O 1 -b 65536 -f 8192"
   show incorrect results from "df" for free and used space when mounted
   immediately after creation. fsck on the new filesystem (before ever
   mounting it once) gives a "SUMMARY INFORMATION BAD" error in phase 5.
   
   This error hasn't occurred in any runs of fsck immediately after
   "newfs -U -b 65536 -f 8192" (leaving out the "-O 1" option).
   
   Solution:
   The default UFS1 superblock is located at offset 8K in the filesystem
   partition; the default UFS2 superblock is located at offset 64K in
   the filesystem partition. For UFS1 filesystems with a blocksize of
   64K, the first alternate superblock resides at 64K which is the the
   location used for the default UFS2 superblock. By default, the
   system first checks for a valid superblock at the default location
   for a UFS2 filoesystem. For a UFS1 filesystem with a blocksize of
   64K, there is a valid UFS1 superblock at this location.  Thus, even
   though it is expected to be a backup superblock, the system will
   use it as its default superblock. So, we have to ensure that all the
   statistcs on usage are correct in this first alternate superblock
   as it is the superblock that will actually be used.
   
   While tracking down this problem, another limitation of UFS1 became
   evident. For UFS1, the number of inodes per cylinder group is stored
   in an int16_t. Thus the maximum number of inodes per cylinder group
   is limited to 2^15 - 1. This limit can easily be exceeded for block
   sizes of 32K and above. Thus when building UFS1 filesystems, newfs
   must limit the number of inodes per cylinder group to 2^15 - 1.
   
   Reported by: Guy Helmer<ghelmer at palisadesys.com>
   Followup by: Bruce Cran <brucec at freebsd.org>
   PR:          107692
   MFC after:   4 weeks
 
 Modified:
   head/sbin/newfs/mkfs.c
 
 Modified: head/sbin/newfs/mkfs.c
 ==============================================================================
 --- head/sbin/newfs/mkfs.c	Fri Sep 24 19:07:14 2010	(r213118)
 +++ head/sbin/newfs/mkfs.c	Fri Sep 24 19:08:56 2010	(r213119)
 @@ -376,16 +376,20 @@ restart:
  	 * Start packing more blocks into the cylinder group until
  	 * it cannot grow any larger, the number of cylinder groups
  	 * drops below MINCYLGRPS, or we reach the size requested.
 +	 * For UFS1 inodes per cylinder group are stored in an int16_t
 +	 * so fs_ipg is limited to 2^15 - 1.
  	 */
  	for ( ; sblock.fs_fpg < maxblkspercg; sblock.fs_fpg += sblock.fs_frag) {
  		sblock.fs_ipg = roundup(howmany(sblock.fs_fpg, fragsperinode),
  		    INOPB(&sblock));
 -		if (sblock.fs_size / sblock.fs_fpg < MINCYLGRPS)
 -			break;
 -		if (CGSIZE(&sblock) < (unsigned long)sblock.fs_bsize)
 -			continue;
 -		if (CGSIZE(&sblock) == (unsigned long)sblock.fs_bsize)
 -			break;
 +		if (Oflag > 1 || (Oflag == 1 && sblock.fs_ipg <= 0x7fff)) {
 +			if (sblock.fs_size / sblock.fs_fpg < MINCYLGRPS)
 +				break;
 +			if (CGSIZE(&sblock) < (unsigned long)sblock.fs_bsize)
 +				continue;
 +			if (CGSIZE(&sblock) == (unsigned long)sblock.fs_bsize)
 +				break;
 +		}
  		sblock.fs_fpg -= sblock.fs_frag;
  		sblock.fs_ipg = roundup(howmany(sblock.fs_fpg, fragsperinode),
  		    INOPB(&sblock));
 @@ -584,8 +588,20 @@ restart:
  		printf("** Exiting on Xflag 3\n");
  		exit(0);
  	}
 -	if (!Nflag)
 +	if (!Nflag) {
  		do_sbwrite(&disk);
 +		/*
 +		 * For UFS1 filesystems with a blocksize of 64K, the first
 +		 * alternate superblock resides at the location used for
 +		 * the default UFS2 superblock. As there is a valid
 +		 * superblock at this location, the boot code will use
 +		 * it as its first choice. Thus we have to ensure that
 +		 * all of its statistcs on usage are correct.
 +		 */
 +		if (Oflag == 1 && sblock.fs_bsize == 65536)
 +			wtfs(fsbtodb(&sblock, cgsblock(&sblock, 0)),
 +			    sblock.fs_bsize, (char *)&sblock);
 +	}
  	for (i = 0; i < sblock.fs_cssize; i += sblock.fs_bsize)
  		wtfs(fsbtodb(&sblock, sblock.fs_csaddr + numfrags(&sblock, i)),
  			sblock.fs_cssize - i < sblock.fs_bsize ?
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