diff mbox

[Drbd-dev,v3,06/26] block: Add bio_end_sector()

Message ID 20120925220624.GC22647@google.com (mailing list archive)
State Deferred, archived
Headers show

Commit Message

Kent Overstreet Sept. 25, 2012, 10:06 p.m. UTC 
On Tue, Sep 25, 2012 at 01:54:52PM +0200, Lars Ellenberg wrote:
> On Mon, Sep 24, 2012 at 03:34:46PM -0700, Kent Overstreet wrote:
> > Just a little convenience macro - main reason to add it now is preparing
> > for immutable bio vecs, it'll reduce the size of the patch that puts
> > bi_sector/bi_size/bi_idx into a struct bvec_iter.
> 
> 
> For the DRBD part:
> 
> > diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
> > index 01b2ac6..d90a1fd 100644
> > --- a/drivers/block/drbd/drbd_req.c
> > +++ b/drivers/block/drbd/drbd_req.c
> > @@ -1144,7 +1144,7 @@ void drbd_make_request(struct request_queue *q, struct bio *bio)
> >  	/* to make some things easier, force alignment of requests within the
> >  	 * granularity of our hash tables */
> >  	s_enr = bio->bi_sector >> HT_SHIFT;
> > -	e_enr = bio->bi_size ? (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT : s_enr;
> > +	e_enr = (bio_end_sector(bio) - 1) >> HT_SHIFT;
> 
> You ignored the bio->bi_size ? : ;
> 
> #define bio_end_sector(bio)	((bio)->bi_sector + bio_sectors(bio))
> which turns out (bio->bi_sector + (bio->bi_size >> 9))
> 
> Note that bi_size may be 0, bio_end_sector(bio)-1 then is bi_sector -1,
> for an empty flush with bi_sector == 0, this ends up as (sector_t)-1ULL,
> and this code path breaks horribly.

Man, that was dumb of me - thanks for catching it. Version below look
good?


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Comments

Lars Ellenberg Sept. 26, 2012, 3:16 p.m. UTC | #1 
On Tue, Sep 25, 2012 at 03:06:24PM -0700, Kent Overstreet wrote:
> On Tue, Sep 25, 2012 at 01:54:52PM +0200, Lars Ellenberg wrote:
> > On Mon, Sep 24, 2012 at 03:34:46PM -0700, Kent Overstreet wrote:
> > > Just a little convenience macro - main reason to add it now is preparing
> > > for immutable bio vecs, it'll reduce the size of the patch that puts
> > > bi_sector/bi_size/bi_idx into a struct bvec_iter.
> > 
> > 
> > For the DRBD part:

> Version below look good?
> 
> diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
> index 01b2ac6..47f55db 100644
> --- a/drivers/block/drbd/drbd_req.c
> +++ b/drivers/block/drbd/drbd_req.c
> @@ -1144,7 +1144,7 @@ void drbd_make_request(struct request_queue *q, struct bio *bio)
>  	/* to make some things easier, force alignment of requests within the
>  	 * granularity of our hash tables */
>  	s_enr = bio->bi_sector >> HT_SHIFT;
> -	e_enr = bio->bi_size ? (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT : s_enr;
> +	e_enr = bio->bi_size ? (bio_end_sector(bio) - 1) >> HT_SHIFT : s_enr;
>  
>  	if (likely(s_enr == e_enr)) {
>  		do {

Sure.

Cheers,

	Lars

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diff mbox

Patch

diff --git a/drivers/block/drbd/drbd_req.c b/drivers/block/drbd/drbd_req.c
index 01b2ac6..47f55db 100644
--- a/drivers/block/drbd/drbd_req.c
+++ b/drivers/block/drbd/drbd_req.c
@@ -1144,7 +1144,7 @@  void drbd_make_request(struct request_queue *q, struct bio *bio)
 	/* to make some things easier, force alignment of requests within the
 	 * granularity of our hash tables */
 	s_enr = bio->bi_sector >> HT_SHIFT;
-	e_enr = bio->bi_size ? (bio->bi_sector+(bio->bi_size>>9)-1) >> HT_SHIFT : s_enr;
+	e_enr = bio->bi_size ? (bio_end_sector(bio) - 1) >> HT_SHIFT : s_enr;
 
 	if (likely(s_enr == e_enr)) {
 		do {