linux-kernel - Re: [PATCH v2] fs/libfs: don't assume blocksize <= PAGE_SIZE in generic_check

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Message-ID: <8ffabe04-b12c-4d1c-8e09-f1db8c72e6d5@huawei.com>
Date: Mon, 30 Jun 2025 19:38:25 +0800
From: Baokun Li <libaokun1@...wei.com>
To: Pankaj Raghav <p.raghav@...sung.com>
CC: Christian Brauner <brauner@...nel.org>, <mcgrof@...nel.org>, Jan Kara
	<jack@...e.cz>, Alexander Viro <viro@...iv.linux.org.uk>,
	<linux-kernel@...r.kernel.org>, <kernel@...kajraghav.com>, Zhang Yi
	<yi.zhang@...wei.com>, <linux-fsdevel@...r.kernel.org>,
	<gost.dev@...sung.com>, Yang Erkun <yangerkun@...wei.com>
Subject: Re: [PATCH v2] fs/libfs: don't assume blocksize <= PAGE_SIZE in
 generic_check_addressable

On 2025/6/30 18:40, Pankaj Raghav wrote:
> Since [1], it is possible for filesystems to have blocksize > PAGE_SIZE
> of the system.
>
> Remove the assumption and make the check generic for all blocksizes in
> generic_check_addressable().
>
> [1] https://lore.kernel.org/linux-xfs/20240822135018.1931258-1-kernel@pankajraghav.com/
>
> Reviewed-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>

Looks good. Feel free to add:

Reviewed-by: Baokun Li <libaokun1@...wei.com>

> ---
> Changes since v1:
> - Removed the unnecessary parantheses.
> - Added RVB from Jan Kara (Thanks).
>
>   fs/libfs.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/fs/libfs.c b/fs/libfs.c
> index 4d1862f589e8..f99ecc300647 100644
> --- a/fs/libfs.c
> +++ b/fs/libfs.c
> @@ -1584,13 +1584,17 @@ EXPORT_SYMBOL(generic_file_fsync);
>   int generic_check_addressable(unsigned blocksize_bits, u64 num_blocks)
>   {
>   	u64 last_fs_block = num_blocks - 1;
> -	u64 last_fs_page =
> -		last_fs_block >> (PAGE_SHIFT - blocksize_bits);
> +	u64 last_fs_page, max_bytes;
> +
> +	if (check_shl_overflow(num_blocks, blocksize_bits, &max_bytes))
> +		return -EFBIG;
> +
> +	last_fs_page = (max_bytes >> PAGE_SHIFT) - 1;
>   
>   	if (unlikely(num_blocks == 0))
>   		return 0;
>   
> -	if ((blocksize_bits < 9) || (blocksize_bits > PAGE_SHIFT))
> +	if (blocksize_bits < 9)
>   		return -EINVAL;
>   
>   	if ((last_fs_block > (sector_t)(~0ULL) >> (blocksize_bits - 9)) ||
>
> base-commit: b39f7d75dc41b5f5d028192cd5d66cff71179f35