Re: [PATCH 7/7] iov_iter: remove iov_iter_is_aligned

[Mike Snitzer <snitzer@kernel.org>]

On Fri, Aug 01, 2025 at 04:47:36PM -0700, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> No more callers.
> 
> Signed-off-by: Keith Busch <kbusch@kernel.org>

You had me up until this last patch.

I'm actually making use of iov_iter_is_aligned() in a series of
changes for both NFS and NFSD.  Chuck has included some of the
NFSD changes in his nfsd-testing branch, see:
https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git/commit/?h=nfsd-testing&id=5d78ac1e674b45f9c9e3769b48efb27c44f4e4d3

And the balance of my work that is pending review/inclusion is:
https://lore.kernel.org/linux-nfs/20250731230633.89983-1-snitzer@kernel.org/
https://lore.kernel.org/linux-nfs/20250801171049.94235-1-snitzer@kernel.org/

I only need iov_iter_aligned_bvec, but recall I want to relax its
checking with this patch:
https://lore.kernel.org/linux-nfs/20250708160619.64800-5-snitzer@kernel.org/

Should I just add iov_iter_aligned_bvec() to fs/nfs_common/ so that
both NFS and NFSD can use it?

Thanks,
Mike

> ---
>  include/linux/uio.h |  2 -
>  lib/iov_iter.c      | 95 ---------------------------------------------
>  2 files changed, 97 deletions(-)
> 
> diff --git a/include/linux/uio.h b/include/linux/uio.h
> index 2e86c653186c6..5b127043a1519 100644
> --- a/include/linux/uio.h
> +++ b/include/linux/uio.h
> @@ -286,8 +286,6 @@ size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i);
>  #endif
>  
>  size_t iov_iter_zero(size_t bytes, struct iov_iter *);
> -bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
> -			unsigned len_mask);
>  unsigned long iov_iter_alignment(const struct iov_iter *i);
>  unsigned long iov_iter_gap_alignment(const struct iov_iter *i);
>  void iov_iter_init(struct iov_iter *i, unsigned int direction, const struct iovec *iov,
> diff --git a/lib/iov_iter.c b/lib/iov_iter.c
> index f9193f952f499..2fe66a6b8789e 100644
> --- a/lib/iov_iter.c
> +++ b/lib/iov_iter.c
> @@ -784,101 +784,6 @@ void iov_iter_discard(struct iov_iter *i, unsigned int direction, size_t count)
>  }
>  EXPORT_SYMBOL(iov_iter_discard);
>  
> -static bool iov_iter_aligned_iovec(const struct iov_iter *i, unsigned addr_mask,
> -				   unsigned len_mask)
> -{
> -	const struct iovec *iov = iter_iov(i);
> -	size_t size = i->count;
> -	size_t skip = i->iov_offset;
> -
> -	do {
> -		size_t len = iov->iov_len - skip;
> -
> -		if (len > size)
> -			len = size;
> -		if (len & len_mask)
> -			return false;
> -		if ((unsigned long)(iov->iov_base + skip) & addr_mask)
> -			return false;
> -
> -		iov++;
> -		size -= len;
> -		skip = 0;
> -	} while (size);
> -
> -	return true;
> -}
> -
> -static bool iov_iter_aligned_bvec(const struct iov_iter *i, unsigned addr_mask,
> -				  unsigned len_mask)
> -{
> -	const struct bio_vec *bvec = i->bvec;
> -	unsigned skip = i->iov_offset;
> -	size_t size = i->count;
> -
> -	do {
> -		size_t len = bvec->bv_len - skip;
> -
> -		if (len > size)
> -			len = size;
> -		if (len & len_mask)
> -			return false;
> -		if ((unsigned long)(bvec->bv_offset + skip) & addr_mask)
> -			return false;
> -
> -		bvec++;
> -		size -= len;
> -		skip = 0;
> -	} while (size);
> -
> -	return true;
> -}
> -
> -/**
> - * iov_iter_is_aligned() - Check if the addresses and lengths of each segments
> - * 	are aligned to the parameters.
> - *
> - * @i: &struct iov_iter to restore
> - * @addr_mask: bit mask to check against the iov element's addresses
> - * @len_mask: bit mask to check against the iov element's lengths
> - *
> - * Return: false if any addresses or lengths intersect with the provided masks
> - */
> -bool iov_iter_is_aligned(const struct iov_iter *i, unsigned addr_mask,
> -			 unsigned len_mask)
> -{
> -	if (likely(iter_is_ubuf(i))) {
> -		if (i->count & len_mask)
> -			return false;
> -		if ((unsigned long)(i->ubuf + i->iov_offset) & addr_mask)
> -			return false;
> -		return true;
> -	}
> -
> -	if (likely(iter_is_iovec(i) || iov_iter_is_kvec(i)))
> -		return iov_iter_aligned_iovec(i, addr_mask, len_mask);
> -
> -	if (iov_iter_is_bvec(i))
> -		return iov_iter_aligned_bvec(i, addr_mask, len_mask);
> -
> -	/* With both xarray and folioq types, we're dealing with whole folios. */
> -	if (iov_iter_is_xarray(i)) {
> -		if (i->count & len_mask)
> -			return false;
> -		if ((i->xarray_start + i->iov_offset) & addr_mask)
> -			return false;
> -	}
> -	if (iov_iter_is_folioq(i)) {
> -		if (i->count & len_mask)
> -			return false;
> -		if (i->iov_offset & addr_mask)
> -			return false;
> -	}
> -
> -	return true;
> -}
> -EXPORT_SYMBOL_GPL(iov_iter_is_aligned);
> -
>  static unsigned long iov_iter_alignment_iovec(const struct iov_iter *i)
>  {
>  	const struct iovec *iov = iter_iov(i);
> -- 
> 2.47.3
>