Re: [PATCH v2] vfs: fix readahead(2) on block devices

[Amir Goldstein <amir73il@gmail.com>]

On Mon, Sep 11, 2023 at 2:49 PM Reuben Hawkins <reubenhwk@gmail.com> wrote:
>
> Readahead was factored to call generic_fadvise.  That refactor added an
> S_ISREG restriction which broke readahead on block devices.
>
> This change removes the S_ISREG restriction to fix block device readahead.
> The change also means that readahead will return -ESPIPE on FIFO files
> instead of -EINVAL.
>
> Fixes: 3d8f7615319b ("vfs: implement readahead(2) using POSIX_FADV_WILLNEED")
> Signed-off-by: Reuben Hawkins <reubenhwk@gmail.com>
> ---

Reviewed-by: Amir Goldstein <amir73il@gmail.com>

Christian,

I suggest adding the link to the original bug report on commit:
Closes: https://lore.kernel.org/linux-fsdevel/CAOQ4uxhE8En64rr3mx1UAOqqzb3A-GoeR7cx2D+V73ytr6YLjw@mail.gmail.com/

Thanks,
Amir.

>  mm/readahead.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
>
> diff --git a/mm/readahead.c b/mm/readahead.c
> index e815c114de21..ef3b23a41973 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -734,8 +734,7 @@ ssize_t ksys_readahead(int fd, loff_t offset, size_t count)
>          * on this file, then we must return -EINVAL.
>          */
>         ret = -EINVAL;
> -       if (!f.file->f_mapping || !f.file->f_mapping->a_ops ||
> -           !S_ISREG(file_inode(f.file)->i_mode))
> +       if (!f.file->f_mapping || !f.file->f_mapping->a_ops)
>                 goto out;
>
>         ret = vfs_fadvise(f.file, offset, count, POSIX_FADV_WILLNEED);
> --
> 2.34.1
>