Date: Thu, 15 Oct 2009 10:11:31 +0200 From: Matthias Andree <matthias.andree@gmx.de> To: freebsd-current@freebsd.org Subject: Re: buffers not syncing correctly during shutdown Message-ID: <4AD6D933.1070804@gmx.de> In-Reply-To: <20091014151026.699a5765@ernst.jennejohn.org> References: <permail-200910141049541e86ffa80000566c-a_best01@message-id.uni-muenster.de> <20091014151026.699a5765@ernst.jennejohn.org>
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Gary Jennejohn schrieb: > On Wed, 14 Oct 2009 12:49:54 +0200 (CEST) > Alexander Best <alexbestms@math.uni-muenster.de> wrote: > >> hi there, >> >> to keep it short: >> >> 1. mount a removable device (e.g. an usb stick) (better use -r to prevent data >> loss) >> 2. unplug the device (without unmounting it) >> 3. `shutdown -r now` >> >> what happens is that the usual shutdown routine gets processed until all >> buffers are synced, but then the system stalls. >> >> after resetting the system all devices (which were supposed to be synced) are >> marked dirty and are being fsck'ed. >> >> cheers. >> alex >> >> oh...and i'm running FreeBSD otaku 9.0-CURRENT FreeBSD 9.0-CURRENT #0 r197914: >> Sat Oct 10 02:58:19 CEST 2009 root@otaku:/usr/obj/usr/src/sys/ARUNDEL >> i386 >> > > I'm inclined to say that umount'ing the file systems is failing because > you pulled the USB stick out without doing umount. Of course, that > results in all file systems still being marked dirty. Obviously, this > pathological case isn't being handled. > > I personally don't see why it ever should be handled. This is UNIX not > Windows and users should be smart enough to know that they umount such > devices before removing them otherwise nasty things can happen. 1. If the device for one file system is gone, why would I mark *other* file systems dirty? There is no reason to do so. 2. If a file system was mounted read-only, and its device is removed, there are by definition ZERO dirty buffers that we need to synch on shutdown, so why does the premature unplug-readonly-before-unmount spoil the shutdown?
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