Re: [PATCH 1/3] block: fix arg type of bio_trim()

[Naohiro Aota <Naohiro.Aota@wdc.com>]

On Thu, Jul 08, 2021 at 04:57:22PM +0200, David Sterba wrote:
> On Thu, Jul 08, 2021 at 10:10:55PM +0900, Naohiro Aota wrote:
> > From: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> > 
> > The function bio_trim has offset and size arguments that are declared
> > as int.
> > 
> > The callers of this function uses sector_t type when passing the offset
> > and size e,g. drivers/md/raid1.c:narrow_write_error() and
> > drivers/md/raid1.c:narrow_write_error().
> > 
> > Change offset & size arguments to sector_t type for bio_trim().
> > 
> > Tested-by: Naohiro Aota <naohiro.aota@wdc.com>
> > Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
> > ---
> >  block/bio.c         | 2 +-
> >  include/linux/bio.h | 2 +-
> >  2 files changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/block/bio.c b/block/bio.c
> > index 44205dfb6b60..d342ce84f6cf 100644
> > --- a/block/bio.c
> > +++ b/block/bio.c
> > @@ -1465,7 +1465,7 @@ EXPORT_SYMBOL(bio_split);
> >   * @offset:	number of sectors to trim from the front of @bio
> >   * @size:	size we want to trim @bio to, in sectors
> >   */
> > -void bio_trim(struct bio *bio, int offset, int size)
> > +void bio_trim(struct bio *bio, sector_t offset, sector_t size)
> 
> sectort_t seems to be the right one, there are << 9 in the function so
> that could lead to some bugs if the offset and size are at the boundary.

Sure. I'll add the following ASSERT to catch the case.

diff --git a/block/bio.c b/block/bio.c
index d342ce84f6cf..54b573414126 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1467,10 +1467,14 @@ EXPORT_SYMBOL(bio_split);
  */
 void bio_trim(struct bio *bio, sector_t offset, sector_t size)
 {
+	const uint_max_sectors = UINT_MAX << SECTOR_SHIFT;
+
 	/* 'bio' is a cloned bio which we need to trim to match
 	 * the given offset and size.
 	 */
 
+	ASSERT(offset <= uint_max_sectors && size < uint_max_sectors);
+
 	size <<= 9;
 	if (offset == 0 && size == bio->bi_iter.bi_size)
 		return;


> >  {
> >  	/* 'bio' is a cloned bio which we need to trim to match
> >  	 * the given offset and size.
> > diff --git a/include/linux/bio.h b/include/linux/bio.h
> > index a0b4cfdf62a4..fb663152521e 100644
> > --- a/include/linux/bio.h> > +++ b/include/linux/bio.h
> > @@ -379,7 +379,7 @@ static inline void bip_set_seed(struct bio_integrity_payload *bip,
> >  
> >  #endif /* CONFIG_BLK_DEV_INTEGRITY */
> >  
> > -extern void bio_trim(struct bio *bio, int offset, int size);
> > +void bio_trim(struct bio *bio, sector_t offset, sector_t size);
> 
> You may want to keep the extern for consistency in that file, though
> it's not necessary for the prototype.

True. Chaitanya, what is the intention of droping it? maybe just a mistake?

> The patch is simple I can take it through the btrfs tree with the other
> fixes unless there are objections.