linux-kernel - Re: [PATCH RESEND] mount: warn only once about timestamp range expiration

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Date:   Thu, 20 Jan 2022 10:03:44 -0800
From:   "Darrick J. Wong" <djwong@...nel.org>
To:     Anthony Iliopoulos <ailiop@...e.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Deepa Dinamani <deepa.kernel@...il.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND] mount: warn only once about timestamp range
 expiration

On Wed, Jan 19, 2022 at 09:29:34PM +0100, Anthony Iliopoulos wrote:
> Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp
> expiry") introduced a mount warning regarding filesystem timestamp
> limits, that is printed upon each writable mount or remount.
> 
> This can result in a lot of unnecessary messages in the kernel log in
> setups where filesystems are being frequently remounted (or mounted
> multiple times).
> 
> Avoid this by setting a superblock flag which indicates that the warning
> has been emitted at least once for any particular mount, as suggested in
> [1].
> 
> Signed-off-by: Anthony Iliopoulos <ailiop@...e.com>

I'm glad someone finally turned down the volume on this.
Reviewed-by: Darrick J. Wong <djwong@...nel.org>

--D

> 
> [1] https://lore.kernel.org/CAHk-=wim6VGnxQmjfK_tDg6fbHYKL4EFkmnTjVr9QnRqjDBAeA@mail.gmail.com/
> ---
>  fs/namespace.c     | 2 ++
>  include/linux/fs.h | 1 +
>  2 files changed, 3 insertions(+)
> 
> diff --git a/fs/namespace.c b/fs/namespace.c
> index c6feb92209a6..fec0f79aa2eb 100644
> --- a/fs/namespace.c
> +++ b/fs/namespace.c
> @@ -2583,6 +2583,7 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *
>  	struct super_block *sb = mnt->mnt_sb;
>  
>  	if (!__mnt_is_readonly(mnt) &&
> +	   (!(sb->s_iflags & SB_I_TS_EXPIRY_WARNED)) &&
>  	   (ktime_get_real_seconds() + TIME_UPTIME_SEC_MAX > sb->s_time_max)) {
>  		char *buf = (char *)__get_free_page(GFP_KERNEL);
>  		char *mntpath = buf ? d_path(mountpoint, buf, PAGE_SIZE) : ERR_PTR(-ENOMEM);
> @@ -2597,6 +2598,7 @@ static void mnt_warn_timestamp_expiry(struct path *mountpoint, struct vfsmount *
>  			tm.tm_year+1900, (unsigned long long)sb->s_time_max);
>  
>  		free_page((unsigned long)buf);
> +		sb->s_iflags |= SB_I_TS_EXPIRY_WARNED;
>  	}
>  }
>  
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index f3daaea16554..5c537cd9b006 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1435,6 +1435,7 @@ extern int send_sigurg(struct fown_struct *fown);
>  
>  #define SB_I_SKIP_SYNC	0x00000100	/* Skip superblock at global sync */
>  #define SB_I_PERSB_BDI	0x00000200	/* has a per-sb bdi */
> +#define SB_I_TS_EXPIRY_WARNED 0x00000400 /* warned about timestamp range expiry */
>  
>  /* Possible states of 'frozen' field */
>  enum {
> -- 
> 2.34.1
>