linux-ext4 - Re: [PATCH v5 13/23] fanotify: Allow file handle encoding for unhashed events

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Date:   Thu, 5 Aug 2021 11:39:20 +0200
From:   Jan Kara <jack@...e.cz>
To:     Gabriel Krisman Bertazi <krisman@...labora.com>
Cc:     jack@...e.com, amir73il@...il.com, djwong@...nel.org,
        tytso@....edu, david@...morbit.com, dhowells@...hat.com,
        khazhy@...gle.com, linux-fsdevel@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-api@...r.kernel.org,
        kernel@...labora.com
Subject: Re: [PATCH v5 13/23] fanotify: Allow file handle encoding for
 unhashed events

On Wed 04-08-21 12:06:02, Gabriel Krisman Bertazi wrote:
> FAN_FS_ERROR will report a file handle, but it is a unhashed event.n
						    ^^ an            ^
spurious 'n'.

> Allow passing a NULL hash to fanotify_encode_fh and avoid calculating
> the hash if not needed.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>

Otherwise looks good. Feel free to add:

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

								Honza

> ---
>  fs/notify/fanotify/fanotify.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index a015822e29d8..0d6ba218bc01 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -385,8 +385,12 @@ static int fanotify_encode_fh(struct fanotify_fh *fh, struct inode *inode,
>  	fh->type = type;
>  	fh->len = fh_len;
>  
> -	/* Mix fh into event merge key */
> -	*hash ^= fanotify_hash_fh(fh);
> +	/*
> +	 * Mix fh into event merge key.  Hash might be NULL in case of
> +	 * unhashed FID events (i.e. FAN_FS_ERROR).
> +	 */
> +	if (hash)
> +		*hash ^= fanotify_hash_fh(fh);
>  
>  	return FANOTIFY_FH_HDR_LEN + fh_len;
>  
> -- 
> 2.32.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR