linux-ext4 - Re: [RFC PATCH 4/7] ext2: Use dax_is

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Date: Tue, 30 Jan 2024 12:33:37 +0100
From: Jan Kara <jack@...e.cz>
To: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
Cc: Dan Williams <dan.j.williams@...el.com>,
	Vishal Verma <vishal.l.verma@...el.com>,
	Dave Jiang <dave.jiang@...el.com>, linux-kernel@...r.kernel.org,
	Jan Kara <jack@...e.com>, linux-ext4@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>, linux-mm@...ck.org,
	linux-arch@...r.kernel.org, Matthew Wilcox <willy@...radead.org>,
	nvdimm@...ts.linux.dev, linux-cxl@...r.kernel.org
Subject: Re: [RFC PATCH 4/7] ext2: Use dax_is_supported()

On Mon 29-01-24 16:06:28, Mathieu Desnoyers wrote:
> Use dax_is_supported() to validate whether the architecture has
> virtually aliased caches at mount time.
> 
> This is relevant for architectures which require a dynamic check
> to validate whether they have virtually aliased data caches
> (ARCH_HAS_CACHE_ALIASING_DYNAMIC=y).
> 
> Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches")
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@...icios.com>
> Cc: Jan Kara <jack@...e.com>
> Cc: linux-ext4@...r.kernel.org
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> Cc: linux-mm@...ck.org
> Cc: linux-arch@...r.kernel.org
> Cc: Dan Williams <dan.j.williams@...el.com>
> Cc: Vishal Verma <vishal.l.verma@...el.com>
> Cc: Dave Jiang <dave.jiang@...el.com>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: nvdimm@...ts.linux.dev
> Cc: linux-cxl@...r.kernel.org

Looks good to me (although I share Dave's opinion it would be nice to CC
the whole series to fsdevel - luckily we have lore these days so it is not
that tedious to find the whole series :)). Feel free to add:

Acked-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext2/super.c | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/ext2/super.c b/fs/ext2/super.c
> index 01f9addc8b1f..0398e7a90eb6 100644
> --- a/fs/ext2/super.c
> +++ b/fs/ext2/super.c
> @@ -585,13 +585,13 @@ static int parse_options(char *options, struct super_block *sb,
>  			set_opt(opts->s_mount_opt, XIP);
>  			fallthrough;
>  		case Opt_dax:
> -#ifdef CONFIG_FS_DAX
> -			ext2_msg(sb, KERN_WARNING,
> -		"DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
> -			set_opt(opts->s_mount_opt, DAX);
> -#else
> -			ext2_msg(sb, KERN_INFO, "dax option not supported");
> -#endif
> +			if (dax_is_supported()) {
> +				ext2_msg(sb, KERN_WARNING,
> +					 "DAX enabled. Warning: EXPERIMENTAL, use at your own risk");
> +				set_opt(opts->s_mount_opt, DAX);
> +			} else {
> +				ext2_msg(sb, KERN_INFO, "dax option not supported");
> +			}
>  			break;
>  
>  #if defined(CONFIG_QUOTA)
> -- 
> 2.39.2
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR