linux-kernel - Re: [RFC PATCH 2/4] vfs: make sb_start

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <slyrgedp776oi4zhzqf4i4re5dwu2v4ubclh7rlopq6mfffve4@lpkqxjz36jcj>
Date: Thu, 27 Mar 2025 18:36:57 +0100
From: Jan Kara <jack@...e.cz>
To: James Bottomley <James.Bottomley@...senpartnership.com>
Cc: linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org, 
	mcgrof@...nel.org, jack@...e.cz, hch@...radead.org, david@...morbit.com, 
	rafael@...nel.org, djwong@...nel.org, pavel@...nel.org, peterz@...radead.org, 
	mingo@...hat.com, will@...nel.org, boqun.feng@...il.com
Subject: Re: [RFC PATCH 2/4] vfs: make sb_start_write freezable

On Thu 27-03-25 10:06:11, James Bottomley wrote:
> If a write happens on a frozen filesystem, the s_writers.rw_sem gets
> stuck in TASK_UNINTERRUPTIBLE and inhibits suspending or hibernating
> the system.  Since we want to freeze filesystems first then tasks, we
> need this condition not to inhibit suspend/hibernate, which means the
> wait has to have the TASK_FREEZABLE flag as well.  Use the freezable
> version of percpu-rwsem to ensure this.
> 
> Signed-off-by: James Bottomley <James.Bottomley@...senPartnership.com>

Looks good. Feel free to add:

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

								Honza

> ---
>  include/linux/fs.h | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index dd84d1c3b8af..cbbb704eff74 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1782,7 +1782,8 @@ static inline void __sb_end_write(struct super_block *sb, int level)
>  
>  static inline void __sb_start_write(struct super_block *sb, int level)
>  {
> -	percpu_down_read(sb->s_writers.rw_sem + level - 1);
> +	percpu_down_read_freezable(sb->s_writers.rw_sem + level - 1,
> +				   level == SB_FREEZE_WRITE);
>  }
>  
>  static inline bool __sb_start_write_trylock(struct super_block *sb, int level)
> -- 
> 2.43.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR