Messages in this thread | | | Date | Thu, 27 Apr 2006 12:03:10 -0400 | From | Mark Lord <> | Subject | Re: [PATCH] drivers/scsi/sd.c: fix uninitialized variable in handling medium errors |
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Andrew Morton wrote: > Mark Lord <lkml@rtr.ca> wrote: >>> That's if we think -stable needs this fixed. >> Let's say a bunch of read bio's get coalesced into a single >> 200+ sector request. This then fails on one single bad sector >> out of the 200+. Without the patch, there is a very good chance >> that sd.c will simply fail the entire request, all 200+ sectors. >> >> With the patch, it will fail the first block, and then retry >> the remaining blocks. And repeat this until something works, >> or until everything has failed one by one. > > Yowch. I have the feeling that this'll take our EIO-handling time from > far-too-long to far-too-long*200. > > I am still traumatised by my recent ten-minute wait for a dodgy DVD to > become ejectable. > > I don't think -stable needs this, personally.
Perhaps, perhaps not. The current behaviour is semi *random*, though. Sometimes it may just fail the entire request (wrong!), sometimes it may do the (almost as wrong) fail a block at a time from the beginning, until the bad sector is passed, and then succeed on the remainder.
Ugh. >> What I need to have happen when a request is failed due to bad-media, >> is have it split the request into a sequence of single-block requests >> that are passed to the LLD one at a time. The ones with real bad >> sectors will then be independently failed, and the rest will get done. >> >> Much better. Much more complex.
-- Mark Lord Real-Time Remedies Inc. mlord@pobox.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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