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From: Jan Kara <jack@suse.cz>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Jan Kara <jack@suse.cz>, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 7/9] fsnotify: fix merge with parent mark masks
Date: Mon, 27 Jul 2020 23:27:27 +0200	[thread overview]
Message-ID: <20200727212727.GJ5284@quack2.suse.cz> (raw)
In-Reply-To: <20200722125849.17418-8-amir73il@gmail.com>

On Wed 22-07-20 15:58:47, Amir Goldstein wrote:
> When reporting event with parent/name info, we should not merge
> parent's mark mask and ignore mask, unless the parent has the flag
> FS_EVENT_ON_CHILD in the mask.
> 
> Therefore, in fsnotify_parent(), set the FS_EVENT_ON_CHILD flag in event
> mask only if parent is watching and use this flag to decide if the
> parent mark masks should be merged with child/sb/mount marks.
> 
> After this change, even groups that do not subscribe to events on
> children could get an event with mark iterator type TYPE_CHILD and
> without mark iterator type TYPE_INODE if fanotify has marks on the same
> objects.
> 
> dnotify and inotify event handlers can already cope with that situation.
> audit does not subscribe to events that are possible on child, so won't
> get to this situation. nfsd does not access the marks iterator from its
> event handler at the moment, so it is not affected.
> 
> This is a bit too fragile, so we should prepare all groups to cope with
> mark type TYPE_CHILD preferably using a generic helper.
> 
> Link: https://lore.kernel.org/linux-fsdevel/20200716223441.GA5085@quack2.suse.cz/
> Fixes: ecf13b5f8fd6 ("fsnotify: send event with parent/name info to sb/mount/non-dir marks")
> Signed-off-by: Amir Goldstein <amir73il@gmail.com>

I've folded this into "fsnotify: send event with parent/name info to
sb/mount/non-dir marks".

									Honza

> ---
>  fs/notify/fanotify/fanotify.c |  2 +-
>  fs/notify/fsnotify.c          | 20 +++++++++++++-------
>  2 files changed, 14 insertions(+), 8 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 03e3dce2a97c..3336157d895d 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -538,7 +538,7 @@ static struct fanotify_event *fanotify_alloc_event(struct fsnotify_group *group,
>  		 * in addition to reporting the parent fid and maybe child name.
>  		 */
>  		if ((fid_mode & FAN_REPORT_FID) &&
> -		    (mask & FAN_EVENT_ON_CHILD) && !(mask & FAN_ONDIR))
> +		    id != dirid && !(mask & FAN_ONDIR))
>  			child = id;
>  
>  		id = dirid;
> diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
> index 3b805e05c02d..494d5d70323f 100644
> --- a/fs/notify/fsnotify.c
> +++ b/fs/notify/fsnotify.c
> @@ -215,7 +215,8 @@ int __fsnotify_parent(struct dentry *dentry, __u32 mask, const void *data,
>  		/* Notify both parent and child with child name info */
>  		take_dentry_name_snapshot(&name, dentry);
>  		file_name = &name.name;
> -		mask |= FS_EVENT_ON_CHILD;
> +		if (parent_watched)
> +			mask |= FS_EVENT_ON_CHILD;
>  	}
>  
>  notify:
> @@ -391,8 +392,8 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
>  		inode = dir;
>  	} else if (mask & FS_EVENT_ON_CHILD) {
>  		/*
> -		 * Event on child - report on TYPE_INODE to dir
> -		 * and on TYPE_CHILD to child.
> +		 * Event on child - report on TYPE_INODE to dir if it is
> +		 * watching children and on TYPE_CHILD to child.
>  		 */
>  		child = inode;
>  		inode = dir;
> @@ -406,14 +407,17 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
>  	 * SRCU because we have no references to any objects and do not
>  	 * need SRCU to keep them "alive".
>  	 */
> -	if (!inode->i_fsnotify_marks && !sb->s_fsnotify_marks &&
> +	if (!sb->s_fsnotify_marks &&
>  	    (!mnt || !mnt->mnt_fsnotify_marks) &&
> +	    (!inode || !inode->i_fsnotify_marks) &&
>  	    (!child || !child->i_fsnotify_marks))
>  		return 0;
>  
> -	marks_mask = inode->i_fsnotify_mask | sb->s_fsnotify_mask;
> +	marks_mask = sb->s_fsnotify_mask;
>  	if (mnt)
>  		marks_mask |= mnt->mnt_fsnotify_mask;
> +	if (inode)
> +		marks_mask |= inode->i_fsnotify_mask;
>  	if (child)
>  		marks_mask |= child->i_fsnotify_mask;
>  
> @@ -428,14 +432,16 @@ int fsnotify(__u32 mask, const void *data, int data_type, struct inode *dir,
>  
>  	iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
>  
> -	iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] =
> -		fsnotify_first_mark(&inode->i_fsnotify_marks);
>  	iter_info.marks[FSNOTIFY_OBJ_TYPE_SB] =
>  		fsnotify_first_mark(&sb->s_fsnotify_marks);
>  	if (mnt) {
>  		iter_info.marks[FSNOTIFY_OBJ_TYPE_VFSMOUNT] =
>  			fsnotify_first_mark(&mnt->mnt_fsnotify_marks);
>  	}
> +	if (inode) {
> +		iter_info.marks[FSNOTIFY_OBJ_TYPE_INODE] =
> +			fsnotify_first_mark(&inode->i_fsnotify_marks);
> +	}
>  	if (child) {
>  		iter_info.marks[FSNOTIFY_OBJ_TYPE_CHILD] =
>  			fsnotify_first_mark(&child->i_fsnotify_marks);
> -- 
> 2.17.1
> 
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR

  reply	other threads:[~2020-07-27 21:27 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-22 12:58 [PATCH 0/9] Fixes for fanotify name events Amir Goldstein
2020-07-22 12:58 ` [PATCH 1/9] fanotify: fix reporting event to sb/mount marks Amir Goldstein
2020-07-27 15:17   ` Jan Kara
2020-07-22 12:58 ` [PATCH 2/9] inotify: do not set FS_EVENT_ON_CHILD in non-dir mark mask Amir Goldstein
2020-07-27 15:33   ` Jan Kara
2020-07-22 12:58 ` [PATCH 3/9] audit: do not set FS_EVENT_ON_CHILD in audit marks mask Amir Goldstein
2020-07-27 15:33   ` Jan Kara
2020-07-22 12:58 ` [PATCH 4/9] fsnotify: create helper fsnotify_inode() Amir Goldstein
2020-07-27 16:26   ` Jan Kara
2020-07-22 12:58 ` [PATCH 5/9] fsnotify: simplify dir argument to handle_event() Amir Goldstein
2020-07-27 19:32   ` Jan Kara
2020-07-22 12:58 ` [PATCH 6/9] fsnotify: pass dir and inode arguments to fsnotify() Amir Goldstein
2020-07-27 21:26   ` Jan Kara
2020-07-22 12:58 ` [PATCH 7/9] fsnotify: fix merge with parent mark masks Amir Goldstein
2020-07-27 21:27   ` Jan Kara [this message]
2020-07-22 12:58 ` [PATCH 8/9] fsnotify: create method handle_inode_event() in fsnotify_operations Amir Goldstein
2020-07-27 21:27   ` Jan Kara
2020-07-22 12:58 ` [PATCH 9/9] fsnotify: pass inode to fsnotify_parent() Amir Goldstein
2020-07-27 21:29   ` Jan Kara
2020-07-27 21:57 ` [PATCH 0/9] Fixes for fanotify name events Jan Kara

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