Messages in this thread | | | Date | Tue, 24 Nov 2009 20:56:08 +0100 | From | Jan Kara <> | Subject | Re: Weird I/O errors with USB hard drive not remounting filesystem readonly |
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On Tue 24-11-09 14:28:35, Alan Stern wrote: > On Tue, 24 Nov 2009, Jan Kara wrote: > > > My naive guess would be that those non-retried reads were actually > > readahead. That's not retried if I remember correctly. Later, when we > > really needed the data, we sent another read request... > > That would be my guess too. I don't know how to verify it, though. > > If you're interested in pursuing this farther, I can show you how to > generate equivalent errors on demand using an emulated USB drive. > At this point it's not clear how much more one could learn by doing > this, however. After digging in block layer code, it's as we suspected: In case of host error DID_ERROR (which is our case), scsi request is retried iff it is not a FAILFAST request which is set if bio is doing readahead... So this is explained and everything behaves as it should. Thanks everybody involved :).
Honza
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