Re: [dm-devel] [PATCH RESEND 1/2 block#for-linus] bio, fs: update READA and SWRITE to match the corresponding BIO_RW_* bits

[Jeff Moyer <jmoyer redhat com>]

Vladislav Bolkhovitin <vst vlnb net> writes:

> Jeff Moyer, on 08/05/2010 10:45 PM wrote:
>> Tejun Heo<tj kernel org>  writes:
>>
>>> Commit a82afdf (block: use the same failfast bits for bio and request)
>>> moved BIO_RW_* bits around such that they match up with REQ_* bits.
>>> Unfortunately, fs.h hard coded READ, WRITE, READA and SWRITE as 0, 1,
>>> 2 and 3, and expected them to match with BIO_RW_* bits.  READ/WRITE
>>> didn't change but BIO_RW_AHEAD was moved to bit 4 instead of bit 1,
>>> breaking READA and SWRITE.
>>>
>>> This patch updates READA and SWRITE such that they match the BIO_RW_*
>>> bits again.  A follow up patch will update the definitions to directly
>>> use BIO_RW_* bits so that this kind of breakage won't happen again.
>>>
>>> Stable: The offending commit a82afdf was released with v2.6.32, so
>>> this patch should be applied to all kernels since then but it must
>>> _NOT_ be applied to kernels earlier than that.
>>
>> Would someone be so kind as to remind me how this problem manifests
>> itself?  I know I read this recently, but my memory and googling skills
>> are both failing me.  :(
>
> See http://lkml.org/lkml/2010/7/28/315 and link inside.

Thanks a ton!

-Jeff