Re: [PATCH 3/3] fanotify: fix inconsistent behaviour regarding flag FAN_ONDIR

2014-12-01 Thread Lino Sanfilippo
Hi,

On 01.12.2014 11:05, Jan Kara wrote:
> On Sun 30-11-14 00:37:38, Lino Sanfilippo wrote:
>> Before flag FAN_ONDIR was implicitly set in a marks ignored mask. This led to
>> some inconsistent behaviour:
>> 
>> 1. It was not possible to remove the flag from the ignored mask, once it was 
>> set
>> (implicitly) with a call like
>> 
>> fanotify_mark(fd, FAN_MARK_ADD, FAN_OPEN, AT_FDCWD, "dir");
>> 
>> This was since the needed flag FAN_MARK_ONDIR was only honored when setting a
>> marks mask, but not when removing it. Now FAN_ONDIR is only set when 
>> explicitly
>> passed in the masks parameter. It now is also possible to remove it again:
>> 
>> fanotify_mark(fd, FAN_MARK_ADD, FAN_OPEN | FAN_ONDIR , AT_FDCWD, "dir");
>> fanotify_mark(fd, FAN_MARK_REMOVE, FAN_ONDIR , AT_FDCWD, "dir");
>> 
>> 2. Subsequent calls to fanotify_mark for a mark that had FAN_ONDIR already 
>> set
>> in its mask removed the flag, if it was not specified in the mask parameter
>> again. Thus
>> 
>> fanotify_mark(fd, FAN_MARK_ADD, FAN_OPEN | FAN_ONDIR , AT_FDCWD, "dir");
>> fanotify_mark(fd, FAN_MARK_ADD, FAN_CLOSE, AT_FDCWD, "dir");
>> 
>> set FAN_ONDIR in the first call on the marks mask but also on the ignored
>> mask in the second call. So the first request for DIR events was overwritten.
>> Since the flag is now not set implicitly any longer this cant happen any 
>> more.
>   Ugh, I have to say I don't understand the changelog. From the code I
> think I understood that instead of always adding FAN_ONDIR to ignore mask
> you require FAN_ONDIR to be set in the normal mask. That makes sense to me
> but please make the changelog more comprehensible.

Hm. My intention was to describe at least two cases of strange behaviour
when setting the FAN_ONDIR flag. But maybe the description has indeed
become a little bit too complicated. I will adjust that and resend the
patch.

 Also please add a
> testcase to LTP fanotify() coverage for FAN_ONDIR behavior so that we can
> easily see how userspace visible behavior changed / didn't change. Thanks!
> 

Ok, i can do that (it may take a few days until i find the time for it
though). Thank you for review!

Regards,
Lino
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/


Re: [PATCH 3/3] fanotify: fix inconsistent behaviour regarding flag FAN_ONDIR

2014-12-01 Thread Jan Kara
On Sun 30-11-14 00:37:38, Lino Sanfilippo wrote:
> Before flag FAN_ONDIR was implicitly set in a marks ignored mask. This led to
> some inconsistent behaviour:
> 
> 1. It was not possible to remove the flag from the ignored mask, once it was 
> set
> (implicitly) with a call like
> 
> fanotify_mark(fd, FAN_MARK_ADD, FAN_OPEN, AT_FDCWD, "dir");
> 
> This was since the needed flag FAN_MARK_ONDIR was only honored when setting a
> marks mask, but not when removing it. Now FAN_ONDIR is only set when 
> explicitly
> passed in the masks parameter. It now is also possible to remove it again:
> 
> fanotify_mark(fd, FAN_MARK_ADD, FAN_OPEN | FAN_ONDIR , AT_FDCWD, "dir");
> fanotify_mark(fd, FAN_MARK_REMOVE, FAN_ONDIR , AT_FDCWD, "dir");
> 
> 2. Subsequent calls to fanotify_mark for a mark that had FAN_ONDIR already set
> in its mask removed the flag, if it was not specified in the mask parameter
> again. Thus
> 
> fanotify_mark(fd, FAN_MARK_ADD, FAN_OPEN | FAN_ONDIR , AT_FDCWD, "dir");
> fanotify_mark(fd, FAN_MARK_ADD, FAN_CLOSE, AT_FDCWD, "dir");
> 
> set FAN_ONDIR in the first call on the marks mask but also on the ignored
> mask in the second call. So the first request for DIR events was overwritten.
> Since the flag is now not set implicitly any longer this cant happen any more.
  Ugh, I have to say I don't understand the changelog. From the code I
think I understood that instead of always adding FAN_ONDIR to ignore mask
you require FAN_ONDIR to be set in the normal mask. That makes sense to me
but please make the changelog more comprehensible. Also please add a
testcase to LTP fanotify() coverage for FAN_ONDIR behavior so that we can
easily see how userspace visible behavior changed / didn't change. Thanks!

Honza
 

> Signed-off-by: Lino Sanfilippo 
> ---
>  fs/notify/fanotify/fanotify.c  |  2 +-
>  fs/notify/fanotify/fanotify_user.c | 24 
>  2 files changed, 17 insertions(+), 9 deletions(-)
> 
> diff --git a/fs/notify/fanotify/fanotify.c b/fs/notify/fanotify/fanotify.c
> index 30d3add..51ceb81 100644
> --- a/fs/notify/fanotify/fanotify.c
> +++ b/fs/notify/fanotify/fanotify.c
> @@ -140,7 +140,7 @@ static bool fanotify_should_send_event(struct 
> fsnotify_mark *inode_mark,
>   }
>  
>   if (S_ISDIR(path->dentry->d_inode->i_mode) &&
> - (marks_ignored_mask & FS_ISDIR))
> + !(marks_mask & FS_ISDIR & ~marks_ignored_mask))
>   return false;
>  
>   if (event_mask & marks_mask & ~marks_ignored_mask)
> diff --git a/fs/notify/fanotify/fanotify_user.c 
> b/fs/notify/fanotify/fanotify_user.c
> index 3afd8bb..e62463e 100644
> --- a/fs/notify/fanotify/fanotify_user.c
> +++ b/fs/notify/fanotify/fanotify_user.c
> @@ -493,10 +493,17 @@ static __u32 fanotify_mark_remove_from_mask(struct 
> fsnotify_mark *fsn_mark,
>  
>   spin_lock(&fsn_mark->lock);
>   if (!(flags & FAN_MARK_IGNORED_MASK)) {
> + __u32 tmask = fsn_mark->mask & ~mask;
> + if (flags & FAN_MARK_ONDIR)
> + tmask &= ~FAN_ONDIR;
> +
>   oldmask = fsn_mark->mask;
> - fsnotify_set_mark_mask_locked(fsn_mark, (oldmask & ~mask));
> + fsnotify_set_mark_mask_locked(fsn_mark, tmask);
>   } else {
>   __u32 tmask = fsn_mark->ignored_mask & ~mask;
> + if (flags & FAN_MARK_ONDIR)
> + tmask &= ~FAN_ONDIR;
> +
>   fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
>   }
>   new_mask = fsn_mark->mask;
> @@ -573,20 +580,21 @@ static __u32 fanotify_mark_add_to_mask(struct 
> fsnotify_mark *fsn_mark,
>  
>   spin_lock(&fsn_mark->lock);
>   if (!(flags & FAN_MARK_IGNORED_MASK)) {
> + __u32 tmask = fsn_mark->mask | mask;
> + if (flags & FAN_MARK_ONDIR)
> + tmask |= FAN_ONDIR;
> +
>   oldmask = fsn_mark->mask;
> - fsnotify_set_mark_mask_locked(fsn_mark, (oldmask | mask));
> + fsnotify_set_mark_mask_locked(fsn_mark, tmask);
>   } else {
>   __u32 tmask = fsn_mark->ignored_mask | mask;
> + if (flags & FAN_MARK_ONDIR)
> + tmask |= FAN_ONDIR;
> +
>   fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
>   if (flags & FAN_MARK_IGNORED_SURV_MODIFY)
>   fsn_mark->flags |= 
> FSNOTIFY_MARK_FLAG_IGNORED_SURV_MODIFY;
>   }
> -
> - if (!(flags & FAN_MARK_ONDIR)) {
> - __u32 tmask = fsn_mark->ignored_mask | FAN_ONDIR;
> - fsnotify_set_mark_ignored_mask_locked(fsn_mark, tmask);
> - }
> -
>   spin_unlock(&fsn_mark->lock);
>  
>   return mask & ~oldmask;
> -- 
> 1.9.1
> 
-- 
Jan Kara 
SUSE Labs, CR
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.htm