linux-kernel - [PATCH 3/3] fanotify: fix inconsistent behaviour regarding flag FAN

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Message-Id: <1417304258-16838-3-git-send-email-LinoSanfilippo@gmx.de>
Date:	Sun, 30 Nov 2014 00:37:38 +0100
From:	Lino Sanfilippo <LinoSanfilippo@....de>
To:	eparis@...hat.com
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	jack@...e.cz, Lino Sanfilippo <LinoSanfilippo@....de>
Subject: [PATCH 3/3] fanotify: fix inconsistent behaviour regarding flag FAN_ONDIR

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.

Signed-off-by: Lino Sanfilippo <LinoSanfilippo@....de>
---
 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

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