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Date:      Sun, 16 Dec 2001 00:08:21 -0500
From:      Jake Burkholder <jake@locore.ca>
To:        freebsd-alpha@freebsd.org
Subject:   HEADS UP Re: cvs commit: src/sys/ufs/ffs ffs_alloc.c ffs_snapshot.c ffs_vfsops.c fs.h
Message-ID:  <20011216000821.D35198@locore.ca>
In-Reply-To: <200112140015.fBE0F6Q99440@freefall.freebsd.org>; from mckusick@FreeBSD.org on Thu, Dec 13, 2001 at 04:15:06PM -0800
References:  <200112140015.fBE0F6Q99440@freefall.freebsd.org>

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This commit breaks binary compatibility of the ffs superblock for
64 bit platforms.  Do not update to -current or you will not be
able to mount your ffs filesystems (unless you use kernel.old).

Have a nice day.

Apparently, On Thu, Dec 13, 2001 at 04:15:06PM -0800,
	Kirk McKusick said words to the effect of;

> mckusick    2001/12/13 16:15:06 PST
> 
>   Modified files:
>     sys/ufs/ffs          ffs_alloc.c ffs_snapshot.c ffs_vfsops.c 
>                          fs.h 
>   Log:
>   Minimize the time necessary to suspend operations on a filesystem
>   when taking a snapshot. The two time consuming operations are
>   scanning all the filesystem bitmaps to determine which blocks
>   are in use and scanning all the other snapshots so as to be able
>   to expunge their blocks from the view of the current snapshot.
>   The bitmap scanning is broken into two passes. Before suspending
>   the filesystem all bitmaps are scanned. After the suspension,
>   those bitmaps that changed after being scanned the first time
>   are rescanned. Typically there are few bitmaps that need to be
>   rescanned. The expunging of other snapshots is now done after
>   the suspension is released by observing that we can easily
>   identify any blocks that were allocated to them after the
>   suspension (they will be maked as `not needing to be copied'
>   in the just created snapshot). For all the gory details, see
>   the ``Running fsck in the Background'' paper in the Usenix
>   BSDCon 2002 Conference Proceedings, pages 55-64.
>   
>   Revision  Changes    Path
>   1.82      +15 -1     src/sys/ufs/ffs/ffs_alloc.c
>   1.24      +193 -96   src/sys/ufs/ffs/ffs_snapshot.c
>   1.164     +1 -0      src/sys/ufs/ffs/ffs_vfsops.c
>   1.24      +3 -2      src/sys/ufs/ffs/fs.h

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