fsnotify: place marks on object in order of group memory address

fsnotify_marks currently are placed on objects (inodes or vfsmounts) in
arbitrary order.  This patch places them in order of the group memory address.

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

2 files changed, 55 insertions, 25 deletions

diff --git a/fs/notify/inode_mark.c b/fs/notify/inode_mark.c
index 0c0a48b1659f..83ce6db34039 100644
--- a/fs/notify/inode_mark.c
+++ b/fs/notify/inode_mark.c
@@ -174,15 +174,17 @@ void fsnotify_set_inode_mark_mask_locked(struct fsnotify_mark *mark,
 }
 
 /*
- * Attach an initialized mark to a given group and inode.
+ * Attach an initialized mark to a given inode.
  * These marks may be used for the fsnotify backend to determine which
- * event types should be delivered to which group and for which inodes.
+ * event types should be delivered to which group and for which inodes.  These
+ * marks are ordered according to the group's location in memory.
  */
 int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
                             struct fsnotify_group *group, struct inode *inode,
                             int allow_dups)
 {
-        struct fsnotify_mark *lmark = NULL;
+        struct fsnotify_mark *lmark;
+        struct hlist_node *node, *last = NULL;
         int ret = 0;
 
         mark->flags = FSNOTIFY_MARK_FLAG_INODE;
@@ -192,21 +194,37 @@ int fsnotify_add_inode_mark(struct fsnotify_mark *mark,
 
         spin_lock(&inode->i_lock);
 
-        if (!allow_dups)
-                lmark = fsnotify_find_inode_mark_locked(group, inode);
-        if (!lmark) {
-                mark->i.inode = inode;
+        mark->i.inode = inode;
 
+        /* is mark the first mark? */
+        if (hlist_empty(&inode->i_fsnotify_marks)) {
                 hlist_add_head(&mark->i.i_list, &inode->i_fsnotify_marks);
+                goto out;
+        }
+
+        /* should mark be in the middle of the current list? */
+        hlist_for_each_entry(lmark, node, &inode->i_fsnotify_marks, i.i_list) {
+                last = node;
+
+                if ((lmark->group == group) && !allow_dups) {
+                        ret = -EEXIST;
+                        goto out;
+                }
 
-                fsnotify_recalc_inode_mask_locked(inode);
+                if (mark->group < lmark->group)
+                        continue;
+
+                hlist_add_before(&mark->i.i_list, &lmark->i.i_list);
+                goto out;
         }
 
+        BUG_ON(last == NULL);
+        /* mark should be the last entry.  last is the current last entry */
+        hlist_add_after(last, &mark->i.i_list);
+out:
+        fsnotify_recalc_inode_mask_locked(inode);
         spin_unlock(&inode->i_lock);
 
-        if (lmark)
-                ret = -EEXIST;
-
         return ret;
 }
 
diff --git a/fs/notify/vfsmount_mark.c b/fs/notify/vfsmount_mark.c
index ec580a25d293..c4b3f14d2530 100644
--- a/fs/notify/vfsmount_mark.c
+++ b/fs/notify/vfsmount_mark.c
@@ -141,34 +141,46 @@ int fsnotify_add_vfsmount_mark(struct fsnotify_mark *mark,
                                struct fsnotify_group *group, struct vfsmount *mnt,
                                int allow_dups)
 {
-        struct fsnotify_mark *lmark = NULL;
+        struct fsnotify_mark *lmark;
+        struct hlist_node *node, *last = NULL;
         int ret = 0;
 
         mark->flags = FSNOTIFY_MARK_FLAG_VFSMOUNT;
 
-        /*
-         * LOCKING ORDER!!!!
-         * mark->lock
-         * group->mark_lock
-         * mnt->mnt_root->d_lock
-         */
         assert_spin_locked(&mark->lock);
         assert_spin_locked(&group->mark_lock);
 
         spin_lock(&mnt->mnt_root->d_lock);
 
-        if (!allow_dups)
-                lmark = fsnotify_find_vfsmount_mark_locked(group, mnt);
-        if (!lmark) {
-                mark->m.mnt = mnt;
+        mark->m.mnt = mnt;
 
+        /* is mark the first mark? */
+        if (hlist_empty(&mnt->mnt_fsnotify_marks)) {
                 hlist_add_head(&mark->m.m_list, &mnt->mnt_fsnotify_marks);
+                goto out;
+        }
+
+        /* should mark be in the middle of the current list? */
+        hlist_for_each_entry(lmark, node, &mnt->mnt_fsnotify_marks, m.m_list) {
+                last = node;
+
+                if ((lmark->group == group) && !allow_dups) {
+                        ret = -EEXIST;
+                        goto out;
+                }
+
+                if (mark->group < lmark->group)
+                        continue;
 
-                fsnotify_recalc_vfsmount_mask_locked(mnt);
-        } else {
-                ret = -EEXIST;
+                hlist_add_before(&mark->m.m_list, &lmark->m.m_list);
+                goto out;
         }
 
+        BUG_ON(last == NULL);
+        /* mark should be the last entry.  last is the current last entry */
+        hlist_add_after(last, &mark->m.m_list);
+out:
+        fsnotify_recalc_vfsmount_mask_locked(mnt);
         spin_unlock(&mnt->mnt_root->d_lock);
 
         return ret;