linux-kernel - Re: [PATCH 1/3] fanotify: only destroy mark when both mask and ignored

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Date:	Tue, 02 Dec 2014 03:11:01 +0100
From:	Lino Sanfilippo <LinoSanfilippo@....de>
To:	Jan Kara <jack@...e.cz>
CC:	eparis@...hat.com, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH 1/3] fanotify: only destroy mark when both mask and ignored_mask
 are cleared

Hi,

On 01.12.2014 10:04, Jan Kara wrote:
> On Sun 30-11-14 00:37:36, Lino Sanfilippo wrote:
>> In fanotify_mark_remove_from_mask() a mark is destroyed if only one of both
>> bitmasks (mask or ignored_mask) of a mark is cleared. However the other mask
>> may still be set and contain information that should not be lost. Thus only
>> destroy a mark if both masks are cleared.
>> 
>> Signed-off-by: Lino Sanfilippo <LinoSanfilippo@....de>
>> ---
>>  fs/notify/fanotify/fanotify_user.c | 6 +++++-
>>  1 file changed, 5 insertions(+), 1 deletion(-)
>> 
>> diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
>> index c991616..03a0dd1 100644
>> --- a/fs/notify/fanotify/fanotify_user.c
>> +++ b/fs/notify/fanotify/fanotify_user.c
>> @@ -488,6 +488,8 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
>>  					    int *destroy)
>>  {
>>  	__u32 oldmask;
>> +	__u32 new_mask;
>> +	__u32 new_ignored;
>>  
>>  	spin_lock(&fsn_mark->lock);
>>  	if (!(flags & FAN_MARK_IGNORED_MASK)) {
>> @@ -497,9 +499,11 @@ static __u32 fanotify_mark_remove_from_mask(struct fsnotify_mark *fsn_mark,
>>  		oldmask = fsn_mark->ignored_mask;
>>  		fsnotify_set_mark_ignored_mask_locked(fsn_mark, (oldmask & ~mask));
>>  	}
>> +	new_mask = fsn_mark->mask;
>> +	new_ignored = fsn_mark->ignored_mask;
>>  	spin_unlock(&fsn_mark->lock);
>>  
>> -	*destroy = !(oldmask & ~mask);
>> +	*destroy = !(new_mask | new_ignored);
>   There's no need for new variables, is there? You can just set *destroy
> under the spinlock...
> 

youre right, these variables are totally unneeded. I cant remember the
reason why i introduced them (maybe leftovers from an earlier attempt).
I will resend a cleaned up version of that patch.

Regards,
Lino

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