Re: [PATCH v4 03/21] iomap: use GFP_NOWAIT when application for iomap_dio_simple allocations

> From: "Joanne Koong"<[email protected]>
> Date:  Tue, Jul 28, 2026, 05:24
> Subject:  [PATCH v4 03/21] iomap: use GFP_NOWAIT when application for iomap_dio_simple allocations
> To: "Christian Brauner"<[email protected]>, <[email protected]>, "Darrick J . Wong"<[email protected]>, <[email protected]>
> Cc: <[email protected]>, <[email protected]>, "Matthew Wilcox"<[email protected]>, "Jan Kara"<[email protected]>, "Jonathan Corbet"<[email protected]>, "David Sterba"<[email protected]>, "Gao Xiang"<[email protected]>, "Namjae Jeon"<[email protected]>, <[email protected]>, "Jaegeuk Kim"<[email protected]>, "Miklos Szeredi"<[email protected]>, "Andreas Gruenbacher"<[email protected]>, "Mikulas Patocka"<[email protected]>, "Hyunchul Lee"<[email protected]>, "Konstantin Komarov"<[email protected]>, "Carlos Maiolino"<[email protected]>, "Damien Le Moal"<[email protected]>, <[email protected]>, <[email protected]>, <[email protected]>
> From: Christoph Hellwig <[email protected]>
> 
> For non-blocking iocbs we should avoid blocking allocation where
> possible, so switch to a GFP_NOWAIT allocation here.
> 
> Reviewed-by: Darrick J. Wong <[email protected]>
> Reviewed-by: Joanne Koong <[email protected]>
> Signed-off-by: Joanne Koong <[email protected]>
> Signed-off-by: Christoph Hellwig <[email protected]>

Looks good.
Reviewed-by: Fengnan Chang <[email protected]>

> ---
>  fs/iomap/direct-io.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
> index 36c976cf0848..5c28124b9f02 100644
> --- a/fs/iomap/direct-io.c
> +++ b/fs/iomap/direct-io.c
> @@ -986,6 +986,7 @@ static void iomap_dio_simple_end_io(struct bio *bio)
>  ssize_t __iomap_dio_read_simple(struct kiocb *iocb, struct iov_iter *iter,
>                  struct iomap_iter *iomi)
>  {
> +        gfp_t gfp = (iomi->flags & IOMAP_NOWAIT) ? GFP_NOWAIT : GFP_KERNEL;
>          struct iomap_dio_simple *sr;
>          unsigned int alignment;
>          struct bio *bio;
> @@ -1015,7 +1016,11 @@ ssize_t __iomap_dio_read_simple(struct kiocb *iocb, struct iov_iter *iter,
>  
>          bio = bio_alloc_bioset(iomi->iomap.bdev,
>                                 bio_iov_vecs_to_alloc(iter, BIO_MAX_VECS),
> -                               REQ_OP_READ, GFP_KERNEL, &iomap_dio_simple_pool);
> +                               REQ_OP_READ, gfp, &iomap_dio_simple_pool);
> +        if (!bio) {
> +                ret = -EAGAIN;
> +                goto out_dio_end;
> +        }
>          sr = container_of(bio, struct iomap_dio_simple, bio);
>          sr->iocb = iocb;
>          sr->dio_flags = 0;
> -- 
> 2.52.0
>