Date: Sat, 19 Oct 2002 21:57:37 -0700 (PDT) From: Matthew Dillon <dillon@apollo.backplane.com> To: David Schultz <dschultz@uclink.Berkeley.EDU> Cc: Poul-Henning Kamp <phk@critter.freebsd.dk>, Maxim Sobolev <sobomax@FreeBSD.ORG>, hackers@FreeBSD.ORG Subject: Re: Patch to allow a driver to report unrecoverable write errors to the buf layer Message-ID: <200210200457.g9K4vbAE030661@apollo.backplane.com> References: <3DB048B5.21097613@FreeBSD.org> <28472.1035014051@critter.freebsd.dk> <20021020043706.GA23972@HAL9000.homeunix.com>
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:filesystem corruption because the vnode layer would be unaware
:that some buffers had been dropped. How hard would it be to fix this?
Extremely difficult, which is why this is all fantasy and no action.
By the time the filesystem layer gets the notification there is
insufficient information to unwind the original operation(s) without
a huge amount of work. A bitmap write failed? Great! Find the
file that the related bitmap blocks are related to. Good luck! And
that is just one case out of dozens that would require a sophisticated
solution. It might be possible via softupdates, but I shudder at the
level of complexity of code required to support such a beast. Not to
mention the fact that pulling a floppy out a bad time could destroy
far more data then whatever pending write operations might have failed.
It's a waste of time.
-Matt
Matthew Dillon
<dillon@backplane.com>
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