Messages in this thread | | | Date | Wed, 22 Jul 2015 12:51:47 -0600 | From | Jens Axboe <> | Subject | Re: [PATCH] block: add a bi_error field to struct bio |
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On 07/20/2015 07:29 AM, Christoph Hellwig wrote: > Currently we have two different ways to signal an I/O error on a BIO: > > (1) by clearing the BIO_UPTODATE flag > (2) by returning a Linux errno value to the bi_end_io callback > > The first one has the drawback of only communicating a single possible > error (-EIO), and the second one has the drawback of not beeing persistent > when bios are queued up, and are not passed along from child to parent > bio in the ever more popular chaining scenario. Having both mechanisms > available has the additional drawback of utterly confusing driver authors > and introducing bugs where various I/O submitters only deal with one of > them, and the others have to add boilerplate code to deal with both kinds > of error returns. > > So add a new bi_error field to store an errno value directly in struct > bio and remove the existing mechanisms to clean all this up.
I think this is a good change, the only part I _really_ dislike is that this now bumps a struct bio from 2 cache lines to 3. Have you done any perf testing?
-- Jens Axboe
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