linux-ext4 - Re: [PATCH v7 25/28] fanotify: Allow users to request FAN_FS

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Date:   Fri, 15 Oct 2021 14:49:01 +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, dhowells@...hat.com, khazhy@...gle.com,
        linux-fsdevel@...r.kernel.org, linux-ext4@...r.kernel.org,
        linux-api@...r.kernel.org, repnop@...gle.com, kernel@...labora.com
Subject: Re: [PATCH v7 25/28] fanotify: Allow users to request FAN_FS_ERROR
 events

On Thu 14-10-21 18:36:43, Gabriel Krisman Bertazi wrote:
> Wire up the FAN_FS_ERROR event in the fanotify_mark syscall, allowing
> user space to request the monitoring of FAN_FS_ERROR events.
> 
> These events are limited to filesystem marks, so check it is the
> case in the syscall handler.
> 
> Signed-off-by: Gabriel Krisman Bertazi <krisman@...labora.com>

No other comment besides what Amir has written...

								Honza

> ---
>  fs/notify/fanotify/fanotify.c      | 2 +-
>  fs/notify/fanotify/fanotify_user.c | 5 +++++
>  include/linux/fanotify.h           | 6 +++++-
>  3 files changed, 11 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 47e28f418711..d449a23d603f 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -827,7 +827,7 @@ static int fanotify_handle_event(struct fsnotify_group *group, u32 mask,
>  	BUILD_BUG_ON(FAN_OPEN_EXEC_PERM != FS_OPEN_EXEC_PERM);
>  	BUILD_BUG_ON(FAN_FS_ERROR != FS_ERROR);
>  
> -	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 19);
> +	BUILD_BUG_ON(HWEIGHT32(ALL_FANOTIFY_EVENT_BITS) != 20);
>  
>  	mask = fanotify_group_event_mask(group, iter_info, mask, data,
>  					 data_type, dir);
> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
> index 8f7c2f4ce674..5edfd7e3f356 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -1585,6 +1585,11 @@ static int do_fanotify_mark(int fanotify_fd, unsigned int flags, __u64 mask,
>  		fsid = &__fsid;
>  	}
>  
> +	if (mask & FAN_FS_ERROR && mark_type != FAN_MARK_FILESYSTEM) {
> +		ret = -EINVAL;
> +		goto path_put_and_out;
> +	}
> +
>  	/* inode held in place by reference to path; group by fget on fd */
>  	if (mark_type == FAN_MARK_INODE)
>  		inode = path.dentry->d_inode;
> diff --git a/include/linux/fanotify.h b/include/linux/fanotify.h
> index 52d464802d99..616af2ea20f3 100644
> --- a/include/linux/fanotify.h
> +++ b/include/linux/fanotify.h
> @@ -91,9 +91,13 @@ extern struct ctl_table fanotify_table[]; /* for sysctl */
>  #define FANOTIFY_INODE_EVENTS	(FANOTIFY_DIRENT_EVENTS | \
>  				 FAN_ATTRIB | FAN_MOVE_SELF | FAN_DELETE_SELF)
>  
> +/* Events that can only be reported with data type FSNOTIFY_EVENT_ERROR */
> +#define FANOTIFY_ERROR_EVENTS	(FAN_FS_ERROR)
> +
>  /* Events that user can request to be notified on */
>  #define FANOTIFY_EVENTS		(FANOTIFY_PATH_EVENTS | \
> -				 FANOTIFY_INODE_EVENTS)
> +				 FANOTIFY_INODE_EVENTS | \
> +				 FANOTIFY_ERROR_EVENTS)
>  
>  /* Events that require a permission response from user */
>  #define FANOTIFY_PERM_EVENTS	(FAN_OPEN_PERM | FAN_ACCESS_PERM | \
> -- 
> 2.33.0
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR