Re: [PATCH v3 07/35] iomap: introduce IOMAP_F_FSVERITY

["Darrick J. Wong" <djwong@kernel.org>]

On Wed, Feb 18, 2026 at 12:19:07AM +0100, Andrey Albershteyn wrote:
> Flag to indicate to iomap that write is happening beyond EOF and no
> isize checks/update is needed.
> 
> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
> ---
>  fs/iomap/buffered-io.c | 8 +++++---
>  fs/iomap/trace.h       | 3 ++-
>  include/linux/iomap.h  | 5 +++++
>  3 files changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index ee7b845f5bc8..4cf9d0991dc1 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -533,7 +533,8 @@ static int iomap_read_folio_iter(struct iomap_iter *iter,
>  			return 0;
>  
>  		/* zero post-eof blocks as the page may be mapped */
> -		if (iomap_block_needs_zeroing(iter, pos)) {
> +		if (iomap_block_needs_zeroing(iter, pos) &&
> +		    !(iomap->flags & IOMAP_F_FSVERITY)) {
>  			folio_zero_range(folio, poff, plen);
>  			iomap_set_range_uptodate(folio, poff, plen);
>  		} else {
> @@ -1130,13 +1131,14 @@ static int iomap_write_iter(struct iomap_iter *iter, struct iov_iter *i,
>  		 * unlock and release the folio.
>  		 */
>  		old_size = iter->inode->i_size;
> -		if (pos + written > old_size) {
> +		if (pos + written > old_size &&
> +		    !(iter->iomap.flags & IOMAP_F_FSVERITY)) {

I think this flag should be called IOMAP_F_POSTEOF since there's no
"fsverity" logic dependent on this flag; it merely allows read/write
access to folios beyond EOF without any of the usual clamping and
zeroing...

>  			i_size_write(iter->inode, pos + written);
>  			iter->iomap.flags |= IOMAP_F_SIZE_CHANGED;
>  		}
>  		__iomap_put_folio(iter, write_ops, written, folio);
>  
> -		if (old_size < pos)
> +		if (old_size < pos && !(iter->iomap.flags & IOMAP_F_FSVERITY))
>  			pagecache_isize_extended(iter->inode, old_size, pos);
>  
>  		cond_resched();
> diff --git a/fs/iomap/trace.h b/fs/iomap/trace.h
> index 532787277b16..5252051cc137 100644
> --- a/fs/iomap/trace.h
> +++ b/fs/iomap/trace.h
> @@ -118,7 +118,8 @@ DEFINE_RANGE_EVENT(iomap_zero_iter);
>  	{ IOMAP_F_ATOMIC_BIO,	"ATOMIC_BIO" }, \
>  	{ IOMAP_F_PRIVATE,	"PRIVATE" }, \
>  	{ IOMAP_F_SIZE_CHANGED,	"SIZE_CHANGED" }, \
> -	{ IOMAP_F_STALE,	"STALE" }
> +	{ IOMAP_F_STALE,	"STALE" }, \
> +	{ IOMAP_F_FSVERITY,	"FSVERITY" }
>  
>  
>  #define IOMAP_DIO_STRINGS \
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index f0e3ed8ad6a6..94cf6241b37f 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -87,6 +87,11 @@ struct vm_fault;
>  #define IOMAP_F_INTEGRITY	0
>  #endif /* CONFIG_BLK_DEV_INTEGRITY */
>  
> +/*
> + * IO happens beyound inode EOF, fsverity metadata is stored there

s/beyound/beyond/

--d

> + */
> +#define IOMAP_F_FSVERITY	(1U << 10)
> +
>  /*
>   * Flag reserved for file system specific usage
>   */
> -- 
> 2.51.2
> 
>