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Go Back   Linux Archive > Redhat > Device-mapper Development

 
 
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Old 08-22-2012, 07:22 PM
Kent Overstreet
 
Default block: Add an explicit bio flag for bios that own their bvec

On Wed, Aug 22, 2012 at 08:43:52PM +0300, Adrian Bunk wrote:
> On Wed, Aug 22, 2012 at 10:04:05AM -0700, Kent Overstreet wrote:
> >...
> > --- a/include/linux/blk_types.h
> > +++ b/include/linux/blk_types.h
> > @@ -117,6 +117,7 @@ struct bio {
> > * BIO_POOL_IDX()
> > */
> > #define BIO_RESET_BITS 12
> > +#define BIO_OWNS_VEC 12 /* bio_free() should free bvec */
> >...
>
> This doesn't look right.

Well, the first 12 bits are reset, so bit 12 will get preserved... I
guess it's unusual to have a duplicated enum value like that but
BIO_RESET_BITS is just a marker, not a real bit.

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Old 08-22-2012, 08:00 PM
Adrian Bunk
 
Default block: Add an explicit bio flag for bios that own their bvec

On Wed, Aug 22, 2012 at 12:22:41PM -0700, Kent Overstreet wrote:
> On Wed, Aug 22, 2012 at 08:43:52PM +0300, Adrian Bunk wrote:
> > On Wed, Aug 22, 2012 at 10:04:05AM -0700, Kent Overstreet wrote:
> > >...
> > > --- a/include/linux/blk_types.h
> > > +++ b/include/linux/blk_types.h
> > > @@ -117,6 +117,7 @@ struct bio {
> > > * BIO_POOL_IDX()
> > > */
> > > #define BIO_RESET_BITS 12
> > > +#define BIO_OWNS_VEC 12 /* bio_free() should free bvec */
> > >...
> >
> > This doesn't look right.
>
> Well, the first 12 bits are reset, so bit 12 will get preserved... I
> guess it's unusual to have a duplicated enum value like that but
> BIO_RESET_BITS is just a marker, not a real bit.

Wouldn't a BIO_RESET_MASK be better than BIO_RESET_BITS?

cu
Adrian

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Old 08-28-2012, 05:23 PM
Kent Overstreet
 
Default block: Add an explicit bio flag for bios that own their bvec

On Wed, Aug 22, 2012 at 11:00:38PM +0300, Adrian Bunk wrote:
> On Wed, Aug 22, 2012 at 12:22:41PM -0700, Kent Overstreet wrote:
> > On Wed, Aug 22, 2012 at 08:43:52PM +0300, Adrian Bunk wrote:
> > > On Wed, Aug 22, 2012 at 10:04:05AM -0700, Kent Overstreet wrote:
> > > >...
> > > > --- a/include/linux/blk_types.h
> > > > +++ b/include/linux/blk_types.h
> > > > @@ -117,6 +117,7 @@ struct bio {
> > > > * BIO_POOL_IDX()
> > > > */
> > > > #define BIO_RESET_BITS 12
> > > > +#define BIO_OWNS_VEC 12 /* bio_free() should free bvec */
> > > >...
> > >
> > > This doesn't look right.
> >
> > Well, the first 12 bits are reset, so bit 12 will get preserved... I
> > guess it's unusual to have a duplicated enum value like that but
> > BIO_RESET_BITS is just a marker, not a real bit.
>
> Wouldn't a BIO_RESET_MASK be better than BIO_RESET_BITS?

Ehh... Might be good to have BIO_RESET_MASK too, but we really want
BIO_RESET_BITS with the flags as that makes it explicit which flags get
cleared and which don't. At first I was going to add BIO_RESET_MASK too,
but it just seemed to get ugly and verbose and didn't fit nicely
anywhere, so I'm dithering and not doing anything with it for now.

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