| Message ID | 4570836cc62137a9ee788d9c820f58ed8efe9b37.1610170479.git.asml.silence@gmail.com |
|---|---|
| State | New |
| Headers | show |
| Series | no-copy bvec | expand |
On Sat, Jan 09, 2021 at 04:02:58PM +0000, Pavel Begunkov wrote: > zero-length bvec segments are allowed in general, but not handled by bio > and down the block layer so filtered out. This inconsistency may be > confusing and prevent from optimisations. As zero-length segments are > useless and places that were generating them are patched, declare them > not allowed. > > Reviewed-by: Christoph Hellwig <hch@lst.de> > Signed-off-by: Pavel Begunkov <asml.silence@gmail.com> > --- > Documentation/block/biovecs.rst | 2 ++ > Documentation/filesystems/porting.rst | 7 +++++++ > lib/iov_iter.c | 2 -- > 3 files changed, 9 insertions(+), 2 deletions(-) > > diff --git a/Documentation/block/biovecs.rst b/Documentation/block/biovecs.rst > index 36771a131b56..ddb867e0185b 100644 > --- a/Documentation/block/biovecs.rst > +++ b/Documentation/block/biovecs.rst > @@ -40,6 +40,8 @@ normal code doesn't have to deal with bi_bvec_done. > There is a lower level advance function - bvec_iter_advance() - which takes > a pointer to a biovec, not a bio; this is used by the bio integrity code. > > +As of 5.12 bvec segments with zero bv_len are not supported. > + > What's all this get us? > ======================= > > diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst > index 867036aa90b8..c722d94f29ea 100644 > --- a/Documentation/filesystems/porting.rst > +++ b/Documentation/filesystems/porting.rst > @@ -865,3 +865,10 @@ no matter what. Everything is handled by the caller. > > clone_private_mount() returns a longterm mount now, so the proper destructor of > its result is kern_unmount() or kern_unmount_array(). > + > +--- > + > +**mandatory** > + > +zero-length bvec segments are disallowed, they must be filtered out before > +passed on to an iterator. > diff --git a/lib/iov_iter.c b/lib/iov_iter.c > index 1635111c5bd2..7de304269641 100644 > --- a/lib/iov_iter.c > +++ b/lib/iov_iter.c > @@ -72,8 +72,6 @@ > __start.bi_bvec_done = skip; \ > __start.bi_idx = 0; \ > for_each_bvec(__v, i->bvec, __bi, __start) { \ > - if (!__v.bv_len) \ > - continue; \ > (void)(STEP); \ > } \ > } > -- > 2.24.0 > Reviewed-by: Ming Lei <ming.lei@redhat.com> -- Ming
diff --git a/Documentation/block/biovecs.rst b/Documentation/block/biovecs.rst index 36771a131b56..ddb867e0185b 100644 --- a/Documentation/block/biovecs.rst +++ b/Documentation/block/biovecs.rst @@ -40,6 +40,8 @@ normal code doesn't have to deal with bi_bvec_done. There is a lower level advance function - bvec_iter_advance() - which takes a pointer to a biovec, not a bio; this is used by the bio integrity code. +As of 5.12 bvec segments with zero bv_len are not supported. + What's all this get us? ======================= diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst index 867036aa90b8..c722d94f29ea 100644 --- a/Documentation/filesystems/porting.rst +++ b/Documentation/filesystems/porting.rst @@ -865,3 +865,10 @@ no matter what. Everything is handled by the caller. clone_private_mount() returns a longterm mount now, so the proper destructor of its result is kern_unmount() or kern_unmount_array(). + +--- + +**mandatory** + +zero-length bvec segments are disallowed, they must be filtered out before +passed on to an iterator. diff --git a/lib/iov_iter.c b/lib/iov_iter.c index 1635111c5bd2..7de304269641 100644 --- a/lib/iov_iter.c +++ b/lib/iov_iter.c @@ -72,8 +72,6 @@ __start.bi_bvec_done = skip; \ __start.bi_idx = 0; \ for_each_bvec(__v, i->bvec, __bi, __start) { \ - if (!__v.bv_len) \ - continue; \ (void)(STEP); \ } \ }