[PATCH 5/7] fsnotify: allow addition of duplicate fsnotify marks

[Eric Paris <eparis@redhat.com>]

This patch allows a task to add a second fsnotify mark to an inode for the
same group.  This mark will be added to the end of the inode's list and
this will never be found by the stand fsnotify_find_mark() function.   This
is useful if a user wants to add a new mark before removing the old one.

Signed-off-by: Eric Paris <eparis@redhat.com>
---

 fs/notify/dnotify/dnotify.c      |    2 +-
 fs/notify/inode_mark.c           |    8 +++++---
 fs/notify/inotify/inotify_user.c |    2 +-
 include/linux/fsnotify_backend.h |    2 +-
 kernel/audit_watch.c             |    2 +-
 5 files changed, 9 insertions(+), 7 deletions(-)

diff --git a/fs/notify/dnotify/dnotify.c b/fs/notify/dnotify/dnotify.c
index 828a889..6b71be9 100644
--- a/fs/notify/dnotify/dnotify.c
+++ b/fs/notify/dnotify/dnotify.c
@@ -361,7 +361,7 @@ int fcntl_dirnotify(int fd, struct file *filp, unsigned long arg)
 		dnentry = container_of(entry, struct dnotify_mark_entry, fsn_entry);
 		spin_lock(&entry->lock);
 	} else {
-		fsnotify_add_mark(new_entry, dnotify_group, inode);
+		fsnotify_add_mark(new_entry, dnotify_group, inode, 0);
 		spin_lock(&new_entry->lock);
 		entry = new_entry;
 		dnentry = new_dnentry;
diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index f560ad5..3f3261b 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -313,9 +313,10 @@ void fsnotify_init_mark(struct fsnotify_mark_entry *entry,
  * event types should be delivered to which group and for which inodes.
  */
 int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
-		      struct fsnotify_group *group, struct inode *inode)
+		      struct fsnotify_group *group, struct inode *inode,
+		      int allow_dups)
 {
-	struct fsnotify_mark_entry *lentry;
+	struct fsnotify_mark_entry *lentry = NULL;
 	int ret = 0;
 
 	inode = igrab(inode);
@@ -335,7 +336,8 @@ int fsnotify_add_mark(struct fsnotify_mark_entry *entry,
 	entry->group = group;
 	entry->inode = inode;
 
-	lentry = fsnotify_find_mark_entry(group, inode);
+	if (!allow_dups)
+		lentry = fsnotify_find_mark_entry(group, inode);
 	if (!lentry) {
 		hlist_add_head(&entry->i_list, &inode->i_fsnotify_mark_entries);
 		list_add(&entry->g_list, &group->mark_entries);
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index 982a412..289a7ce 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -467,7 +467,7 @@ find_entry:
 			goto out_err;
 		}
 
-		ret = fsnotify_add_mark(&ientry->fsn_entry, group, inode);
+		ret = fsnotify_add_mark(&ientry->fsn_entry, group, inode, 0);
 		if (ret == -EEXIST)
 			goto find_entry;
 		else if (ret)
diff --git a/include/linux/fsnotify_backend.h b/include/linux/fsnotify_backend.h
index 4c187c6..2ab2b7d 100644
--- a/include/linux/fsnotify_backend.h
+++ b/include/linux/fsnotify_backend.h
@@ -345,7 +345,7 @@ extern struct fsnotify_mark_entry *fsnotify_find_mark_entry(struct fsnotify_grou
 /* copy the values from old into new */
 extern void fsnotify_duplicate_mark(struct fsnotify_mark_entry *new, struct fsnotify_mark_entry *old);
 /* attach the mark to both the group and the inode */
-extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode);
+extern int fsnotify_add_mark(struct fsnotify_mark_entry *entry, struct fsnotify_group *group, struct inode *inode, int allow_dups);
 /* given a mark, flag it to be freed when all references are dropped */
 extern void fsnotify_destroy_mark_by_entry(struct fsnotify_mark_entry *entry);
 /* run all the marks in a group, and flag them to be freed */
diff --git a/kernel/audit_watch.c b/kernel/audit_watch.c
index 231f2a6..e56286b 100644
--- a/kernel/audit_watch.c
+++ b/kernel/audit_watch.c
@@ -163,7 +163,7 @@ static struct audit_parent *audit_init_parent(struct path *parent_path)
 
 	fsnotify_init_mark(&parent->mark, audit_watch_free_mark);
 	parent->mark.mask = AUDIT_FS_WATCH;
-	ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode);
+	ret = fsnotify_add_mark(&parent->mark, audit_watch_group, inode, 0);
 	if (ret < 0) {
 		audit_free_parent(parent);
 		return ERR_PTR(ret);