fsnotify: send path type events to group with super block marks

Send events to group if super block mark mask matches the event
and unless the same group has an ignore mask on the vfsmount or
the inode on which the event occurred.

Soon, fanotify backend is going to support super block marks and
fanotify backend only supports path type events.

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/notify/fsnotify.c

@@ -325,15 +325,18 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	     const unsigned char *file_name, u32 cookie)
 {
 	struct fsnotify_iter_info iter_info = {};
-	struct mount *mnt;
+	struct super_block *sb = NULL;
+	struct mount *mnt = NULL;
+	__u32 mnt_or_sb_mask = 0;
 	int ret = 0;
 	/* global tests shouldn't care about events on child only the specific event */
 	__u32 test_mask = (mask & ~FS_EVENT_ON_CHILD);
 
-	if (data_is == FSNOTIFY_EVENT_PATH)
+	if (data_is == FSNOTIFY_EVENT_PATH) {
 		mnt = real_mount(((const struct path *)data)->mnt);
-	else
-		mnt = NULL;
+		sb = mnt->mnt.mnt_sb;
+		mnt_or_sb_mask = mnt->mnt_fsnotify_mask | sb->s_fsnotify_mask;
+	}
 
 	/*
 	 * Optimization: srcu_read_lock() has a memory barrier which can
@@ -343,16 +346,15 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	 * need SRCU to keep them "alive".
 	 */
 	if (!to_tell->i_fsnotify_marks &&
-	    (!mnt || !mnt->mnt_fsnotify_marks))
+	    (!mnt || (!mnt->mnt_fsnotify_marks && !sb->s_fsnotify_marks)))
 		return 0;
 	/*
 	 * if this is a modify event we may need to clear the ignored masks
-	 * otherwise return if neither the inode nor the vfsmount care about
+	 * otherwise return if neither the inode nor the vfsmount/sb care about
 	 * this type of event.
 	 */
 	if (!(mask & FS_MODIFY) &&
-	    !(test_mask & to_tell->i_fsnotify_mask) &&
-	    !(mnt && test_mask & mnt->mnt_fsnotify_mask))
+	    !(test_mask & (to_tell->i_fsnotify_mask | mnt_or_sb_mask)))
 		return 0;
 
 	iter_info.srcu_idx = srcu_read_lock(&fsnotify_mark_srcu);
@@ -362,11 +364,13 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
 	if (mnt) {
 		iter_info.marks[FSNOTIFY_OBJ_TYPE_VFSMOUNT] =
 			fsnotify_first_mark(&mnt->mnt_fsnotify_marks);
+		iter_info.marks[FSNOTIFY_OBJ_TYPE_SB] =
+			fsnotify_first_mark(&sb->s_fsnotify_marks);
 	}
 
 	/*
-	 * We need to merge inode & vfsmount mark lists so that inode mark
-	 * ignore masks are properly reflected for mount mark notifications.
+	 * We need to merge inode/vfsmount/sb mark lists so that e.g. inode mark
+	 * ignore masks are properly reflected for mount/sb mark notifications.
 	 * That's why this traversal is so complicated...
 	 */
 	while (fsnotify_iter_select_report_types(&iter_info)) {