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

Tao Ma tao.ma at oracle.com
Fri Aug 6 04:04:43 UTC 2010


Hi Tejun,

On 08/06/2010 02:45 AM, Jeff Moyer wrote:
> Tejun Heo<tj at 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.
If only this patch goes into stable, do we need to change RWA_MASK in 
this patch also(I have seen you change it the 2/2)?

-#define RWA_MASK        2
+#define RWA_MASK        16

Regards,
Tao




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