Preliminary version of resize_ffs, based on der Mouse's fsresize tool.

I didn't have time to clean it up completely before my legal status
w.r.t. open source projects goes into limbo for a while.  Other
developers are encouraged to play with the tool and get it into
release-worthy shape.

TODO list (see TODO file)

* verify it builds on -current, put it into release lists/etc. and src/sbin/Makefile
  (built & tested on 1.6.1)
* make it ask questions before doing any work (confirm)
* create regression test suite (see discussions on tech-kern and
  developers) and fix any bugs
* verify conversion to ANSI C didn't break anything
* port to UFS2

sbin/resize_ffs/Makefile

@@ -0,0 +1,6 @@
+#	$NetBSD: Makefile,v 1.1 2003/02/21 04:08:54 jtk Exp $
+
+PROG=resize_ffs
+MAN=resize_ffs.8
+
+.include <bsd.prog.mk>

sbin/resize_ffs/TODO

@@ -0,0 +1,15 @@
+Preliminary version of resize_ffs, based on der Mouse's fsresize tool.
+I didn't have time to clean it up completely before my legal status
+w.r.t. open source projects goes into limbo for a while.  Other
+developers are encouraged to play with the tool and get it into
+release-worthy shape.
+
+TODO list (see TODO file)
+
+* verify it builds on -current, put it into release lists/etc. and src/sbin/Makefile
+  (built & tested on 1.6.1)
+* make it ask questions before doing any work (confirm)
+* create regression test suite (see discussions on tech-kern and
+  developers) and fix any bugs
+* verify conversion to ANSI C didn't break anything
+* port to UFS2

sbin/resize_ffs/resize_ffs.8

@@ -0,0 +1,105 @@
+.\"     $NetBSD: resize_ffs.8,v 1.1 2003/02/21 04:08:55 jtk Exp $
+.\" As its sole author, I explicitly place this man page in the public
+.\" domain.  Anyone may use it in any way for any purpose (though I would
+.\" appreciate credit where it is due).
+.\"
+.\" /~\ The ASCII                           der Mouse
+.\" \ / Ribbon Campaign
+.\"  X  Against HTML               mouse@rodents.montreal.qc.ca
+.\" / \ Email!           7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B
+.Dd February 20, 2003
+.Dt RESIZE_FFS 8
+.Sh NAME
+.Nm resize_ffs
+.Nd resize an on-disk filesystem
+.Sh SYNOPSIS
+.Nm
+.Ar filesystem-raw-device
+.Ar newsize
+.Sh DESCRIPTION
+.Nm
+resizes a filesystem on disk.
+.Ar filesystem
+is the name of the raw disk device where the filesystem resides;
+.Ar newsize
+is the desired new filesystem size, in sectors.  (Sectors are almost
+always 512 bytes, and
+.Nm
+can both grow and shrink filesystems.  When growing, the disk device
+must of course be large enough to contain the new filesystem;
+.Nm
+simply extends the filesystem data structures into the new space.  When
+shrinking,
+.Nm
+assumes this.  It will not work correctly for filesystems with other
+sector sizes.)
+.Nm
+has to copy anything that currently resides in the space being shrunk
+away; there must be enough space free on the filesystem for this to
+succeed.  If there isn't,
+.Nm
+will complain and exit; when this happens, it attempts to always leave
+the filesystem in a consistent state, but it is probably a good idea to
+check the filesystem with
+.Xr fsck 8 .
+.Pp
+.Sh WARNING
+.Nm
+should still be considered experimental.  It still needs to be validated
+with a rigorous regression test suite.
+
+.Em Interrupting
+.Nm
+.Em "may leave your file system in an inconsistent state and require a"
+.Em "restore from backup."
+It attempts to write in the proper order to avoid problems, but as it is
+still considered experimental, you should take great care when using it.
+.Pp
+When
+.Nm
+is applied to a consistent filesystem, it should always produce a
+consistent filesystem; if the filesystem is not consistent to start
+with,
+.Nm
+may misbehave, anything from dumping core to completely curdling the
+data.  It's probably wise to
+.Xr fsck 8
+the filesystem before and after, just to be safe.
+.\" Remove this when (if) fsck gets fixed.
+.Pp
+There is a bug somewhere in fsck; it does not check certain data
+structures enough.  A past version of this program had a bug that
+produced corrupted rotation layout summary tables, which would panic
+the kernel.  This bug is believed fixed, and there are currently no
+known bugs in the program.  However, you should be aware that just
+because fsck is happy with the filesystem does not mean it is intact.
+.Sh EXAMPLES
+.Nm
+.Li /dev/rsd1e 29574
+.Sh SEE ALSO
+.Xr fs 5 ,
+.Xr newfs 8 ,
+.Xr fsck 8
+.Sh AUTHOR
+.Li der Mouse <mouse@rodents.montreal.qc.ca>
+.Pp
+A big bug-finding kudos goes to John Kohl for finding the rotational
+layout bug referred
+to in the WARNING section above.
+.Sh BUGS
+Has not been tested and probably won't work on opposite-endian file
+systems.
+.Pp
+Can fail to shrink a filesystem when there actually is enough space,
+because it does not distinguish between a block allocated as a block
+and a block fully occupied by two or more frags.  This is unlikely to
+occur in practice; except for pathological cases, it can happen only
+when the new size is extremely close to the minimum possible.
+.Pp
+Has no intelligence whatever when it comes to allocating blocks to copy
+data into when shrinking.
+.Sh HISTORY
+The
+.Nm
+command first appeared in
+.Nx 2.0 .