Re: [PATCH] mm: Fully initialize invalidate_lock, amend lock class later

[Sebastian Andrzej Siewior <bigeasy@linutronix.de>]

On 2021-09-01 10:44:04 [+0200], To linux-fsdevel@vger.kernel.org wrote:
> The function __init_rwsem() is not part of the official API, it just a helper
> function used by init_rwsem().
> Changing the lock's class and name should be done by using
> lockdep_set_class_and_name() after the has been fully initialized. The overhead
> of the additional class struct and setting it twice is negligible and it works
> across all locks.
> 
> Fully initialize the lock with init_rwsem() and then set the custom class and
> name for the lock.
> 
> Fixes: 730633f0b7f95 ("mm: Protect operations adding pages to page cache with invalidate_lock")
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>

ping.

> ---
>  fs/inode.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/inode.c b/fs/inode.c
> index cb41f02d8cedf..a49695f57e1ea 100644
> --- a/fs/inode.c
> +++ b/fs/inode.c
> @@ -190,8 +190,10 @@ int inode_init_always(struct super_block *sb, struct inode *inode)
>  	mapping_set_gfp_mask(mapping, GFP_HIGHUSER_MOVABLE);
>  	mapping->private_data = NULL;
>  	mapping->writeback_index = 0;
> -	__init_rwsem(&mapping->invalidate_lock, "mapping.invalidate_lock",
> -		     &sb->s_type->invalidate_lock_key);
> +	init_rwsem(&mapping->invalidate_lock);
> +	lockdep_set_class_and_name(&mapping->invalidate_lock,
> +				   &sb->s_type->invalidate_lock_key,
> +				   "mapping.invalidate_lock");
>  	inode->i_private = NULL;
>  	inode->i_mapping = mapping;
>  	INIT_HLIST_HEAD(&inode->i_dentry);	/* buggered by rcu freeing */

Sebastian