Messages in this thread | | | Date | Wed, 26 Apr 2006 21:43:20 -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.
That's how it always used to work (eg. SUSE9 2.6.5+ kernels; Jens?).
>> 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. >> >> I'm thinking about something like that, just not sure whether to put it >> (initially) in libata, sd.c, or the block layer. > > block, I suspect. My DVD trauma was IDE-induced. Jens is mulling the > problem - I'd suggest you coordinate with him.
I've been pinging Jens about it for a couple of weeks now; no response.
> It would be a good thing to fix. > > It's moderately hard to test, though. Easy enough for DVDs and CDs, but > it's harder to take a marker pen to a hard drive.
I have a bunch of "pre-marked" SATA drives here just for the purpose..
Cheers
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