Re: [RFC PATCH 2/4] vfs: make sb_start_write freezable

[Jan Kara]

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@xxxxxxxxxxxxxxxxxxxxx>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@xxxxxxx>

								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@xxxxxxxx>
SUSE Labs, CR