Re: [PATCH v2] btrfs: not a disk error if the bio_add_page fails

[Liu Bo <bo.li.liu@oracle.com>]

On Thu, Jan 04, 2018 at 09:47:56AM -0800, Liu Bo wrote:
> On Wed, Jan 03, 2018 at 09:52:43PM +0800, Anand Jain wrote:
> > bio_add_page() can fail for logical reasons as from the bio_add_page()
> > comments:- 'This will only fail if either
> > bio->bi_vcnt == bio->bi_max_vecs or it's a cloned bio.' Don't inc the
> > write error statistics for this. And set -EINVAL instead of -EIO.
> >
> 
> It's correct to skip increasing counter, but why -EINVAL?
> (its caller only cares about if it's non-zero.)

Well...there is no chance that bio_add_page() could return
non-PAGE_SIZE as this bio has been just created, we can remove the
error handling after bio_add_page().

thanks,
-liubo
> 
> thanks,
> 
> -liubo
> > Signed-off-by: Anand Jain <anand.jain@oracle.com>
> > ---
> > v1->v2: Add missing bio_put(). Thanks Filipe.
> > 
> >  fs/btrfs/scrub.c | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/fs/btrfs/scrub.c b/fs/btrfs/scrub.c
> > index ecfe3118d9dd..57ac39a3f046 100644
> > --- a/fs/btrfs/scrub.c
> > +++ b/fs/btrfs/scrub.c
> > @@ -4617,15 +4617,16 @@ static int write_page_nocow(struct scrub_ctx *sctx,
> >  	bio->bi_opf = REQ_OP_WRITE | REQ_SYNC;
> >  	ret = bio_add_page(bio, page, PAGE_SIZE, 0);
> >  	if (ret != PAGE_SIZE) {
> > -leave_with_eio:
> > +		bio_put(bio);
> > +		return -EINVAL;
> > +	}
> > +
> > +	if (btrfsic_submit_bio_wait(bio)) {
> >  		bio_put(bio);
> >  		btrfs_dev_stat_inc_and_print(dev, BTRFS_DEV_STAT_WRITE_ERRS);
> >  		return -EIO;
> >  	}
> >  
> > -	if (btrfsic_submit_bio_wait(bio))
> > -		goto leave_with_eio;
> > -
> >  	bio_put(bio);
> >  	return 0;
> >  }
> > -- 
> > 2.15.0
> > 
> > --
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