linux-kernel - Re: [PATCH v4] fs/buffer: remove the min and max limit checks in __getblk

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Message-ID: <3398cb62-3666-4a79-84c1-3b967059cd77@huawei.com>
Date: Fri, 27 Jun 2025 10:02:30 +0800
From: Baokun Li <libaokun1@...wei.com>
To: Pankaj Raghav <p.raghav@...sung.com>
CC: Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>,
	<mcgrof@...nel.org>, Alexander Viro <viro@...iv.linux.org.uk>,
	<linux-kernel@...r.kernel.org>, <linux-fsdevel@...r.kernel.org>,
	<kernel@...kajraghav.com>, <gost.dev@...sung.com>, Matthew Wilcox
	<willy@...radead.org>, Zhang Yi <yi.zhang@...wei.com>, Yang Erkun
	<yangerkun@...wei.com>
Subject: Re: [PATCH v4] fs/buffer: remove the min and max limit checks in
 __getblk_slow()

On 2025/6/26 19:32, Pankaj Raghav wrote:
> All filesystems will already check the max and min value of their block
> size during their initialization. __getblk_slow() is a very low-level
> function to have these checks. Remove them and only check for logical
> block size alignment.
>
> As this check with logical block size alignment might never trigger, add
> WARN_ON_ONCE() to the check. As WARN_ON_ONCE() will already print the
> stack, remove the call to dump_stack().
>
> Suggested-by: Matthew Wilcox <willy@...radead.org>
> Reviewed-by: Jan Kara <jack@...e.cz>
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>

Makes sense. Feel free to add:

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

> ---
> Changes since v3:
> - Use WARN_ON_ONCE on the logical block size check and remove the call
>    to dump_stack.
> - Use IS_ALIGNED() to check for aligned instead of open coding the
>    check.
>
>   fs/buffer.c | 11 +++--------
>   1 file changed, 3 insertions(+), 8 deletions(-)
>
> diff --git a/fs/buffer.c b/fs/buffer.c
> index d61073143127..565fe88773c2 100644
> --- a/fs/buffer.c
> +++ b/fs/buffer.c
> @@ -1122,14 +1122,9 @@ __getblk_slow(struct block_device *bdev, sector_t block,
>   {
>   	bool blocking = gfpflags_allow_blocking(gfp);
>   
> -	if (unlikely(size & (bdev_logical_block_size(bdev) - 1) ||
> -		     (size < 512 || size > PAGE_SIZE))) {
> -		printk(KERN_ERR "getblk(): invalid block size %d requested\n",
> -					size);
> -		printk(KERN_ERR "logical block size: %d\n",
> -					bdev_logical_block_size(bdev));
> -
> -		dump_stack();
> +	if (WARN_ON_ONCE(!IS_ALIGNED(size, bdev_logical_block_size(bdev)))) {
> +		printk(KERN_ERR "getblk(): block size %d not aligned to logical block size %d\n",
> +		       size, bdev_logical_block_size(bdev));
>   		return NULL;
>   	}
>   
>
> base-commit: b39f7d75dc41b5f5d028192cd5d66cff71179f35