Re: [PATCH 1/2] btrfs: introduce a common helper to calculate the size of a bio

[David Sterba <dsterba@suse.cz>]

On Wed, Feb 25, 2026 at 07:32:48AM +1030, Qu Wenruo wrote:
> 在 2026/2/25 00:45, David Sterba 写道:
> > On Fri, Feb 20, 2026 at 02:11:50PM +1030, Qu Wenruo wrote:
> >> We have several call sites doing the same work to calculate the size of
> >> a bio:
> >>
> >> 	struct bio_vec *bvec;
> >> 	u32 bio_size = 0;
> >> 	int i;
> >>
> >> 	bio_for_each_bvec_all(bvec, bio, i)
> >> 		bio_size += bvec->bv_len;
> >>
> >> We can use a common helper instead of open-coding it everywhere.
> >>
> >> This also allows us to constify the @bio_size variables used in all the
> >> call sites.
> >>
> >> Signed-off-by: Qu Wenruo <wqu@suse.com>
> >> ---
> >>   fs/btrfs/misc.h   | 15 +++++++++++----
> >>   fs/btrfs/raid56.c |  9 ++-------
> >>   fs/btrfs/scrub.c  | 22 ++++------------------
> >>   3 files changed, 17 insertions(+), 29 deletions(-)
> >>
> >> diff --git a/fs/btrfs/misc.h b/fs/btrfs/misc.h
> >> index 12c5a9d6564f..189c25cc5eff 100644
> >> --- a/fs/btrfs/misc.h
> >> +++ b/fs/btrfs/misc.h
> >> @@ -52,15 +52,22 @@ static inline phys_addr_t bio_iter_phys(struct bio *bio, struct bvec_iter *iter)
> >>   	     (paddr = bio_iter_phys((bio), (iter)), 1);			\
> >>   	     bio_advance_iter_single((bio), (iter), (blocksize)))
> >>   
> >> -/* Initialize a bvec_iter to the size of the specified bio. */
> >> -static inline struct bvec_iter init_bvec_iter_for_bio(struct bio *bio)
> >> +/* Can only be called on a non-cloned bio. */
> > 
> > Please also add an ASSERT for that.
> 
> You know how I like to add ASSERT()s almost everywhere, but for this 
> it's already implied.
> 
> bio_first_bvec_all() has a WARN_ON_ONCE() line for it already.

Ok that's good, I didn't know that.