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

From: Vladislav Bolkhovitin
Date: Thu Aug 05 2010 - 14:57:42 EST



Jeff Moyer, on 08/05/2010 10:45 PM wrote:
Tejun Heo<tj@xxxxxxxxxx> 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.

Vlad
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