fsnotify: introduce marks iteration helpers

Introduce helpers fsnotify_iter_select_report_types() and
fsnotify_iter_next() to abstract the inode/vfsmount marks merged
list iteration.

This is a preparation patch before generalizing mark list
iteration to more mark object types (i.e. super block marks).

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

1 files changed, 49 insertions, 25 deletions

diff --git a/fs/notify/fsnotify.c b/fs/notify/fsnotify.c
index 9a63cf07f858..98e91037b11d 100644
--- a/fs/notify/fsnotify.c
+++ b/fs/notify/fsnotify.c
@@ -261,6 +261,53 @@ static struct fsnotify_mark *fsnotify_next_mark(struct fsnotify_mark *mark)
 }
 
 /*
+ * iter_info is a multi head priority queue of marks.
+ * Pick a subset of marks from queue heads, all with the
+ * same group and set the report_mask for selected subset.
+ * Returns the report_mask of the selected subset.
+ */
+static unsigned int fsnotify_iter_select_report_types(
+                struct fsnotify_iter_info *iter_info)
+{
+        struct fsnotify_mark *inode_mark = iter_info->inode_mark;
+        struct fsnotify_mark *vfsmount_mark = iter_info->vfsmount_mark;
+        int cmp;
+
+        if (!inode_mark && !vfsmount_mark)
+                return 0;
+
+        if (inode_mark && vfsmount_mark) {
+                cmp = fsnotify_compare_groups(inode_mark->group,
+                                              vfsmount_mark->group);
+        } else {
+                cmp = inode_mark ? -1 : 1;
+        }
+
+        iter_info->report_mask = 0;
+        if (cmp <= 0)
+                iter_info->report_mask |= FSNOTIFY_OBJ_TYPE_INODE_FL;
+        if (cmp >= 0)
+                iter_info->report_mask |= FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL;
+
+        return iter_info->report_mask;
+}
+
+/*
+ * Pop from iter_info multi head queue, the marks that were iterated in the
+ * current iteration step.
+ */
+static void fsnotify_iter_next(struct fsnotify_iter_info *iter_info)
+{
+        if (iter_info->report_mask & FSNOTIFY_OBJ_TYPE_INODE_FL)
+                iter_info->inode_mark =
+                        fsnotify_next_mark(iter_info->inode_mark);
+
+        if (iter_info->report_mask & FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL)
+                iter_info->vfsmount_mark =
+                        fsnotify_next_mark(iter_info->vfsmount_mark);
+}
+
+/*
  * This is the main call to fsnotify.  The VFS calls into hook specific functions
  * in linux/fsnotify.h.  Those functions then in turn call here.  Here will call
  * out to all of the registered fsnotify_group.  Those groups can then use the
@@ -321,37 +368,14 @@ int fsnotify(struct inode *to_tell, __u32 mask, const void *data, int data_is,
          * ignore masks are properly reflected for mount mark notifications.
          * That's why this traversal is so complicated...
          */
-        while (iter_info.inode_mark || iter_info.vfsmount_mark) {
-                struct fsnotify_mark *inode_mark = iter_info.inode_mark;
-                struct fsnotify_mark *vfsmount_mark = iter_info.vfsmount_mark;
-                int cmp;
-
-                if (inode_mark && vfsmount_mark) {
-                        cmp = fsnotify_compare_groups(inode_mark->group,
-                                                      vfsmount_mark->group);
-                } else {
-                        cmp = inode_mark ? -1 : 1;
-                }
-
-                iter_info.report_mask = 0;
-                if (cmp <= 0)
-                        iter_info.report_mask |= FSNOTIFY_OBJ_TYPE_INODE_FL;
-                if (cmp >= 0)
-                        iter_info.report_mask |= FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL;
-
+        while (fsnotify_iter_select_report_types(&iter_info)) {
                 ret = send_to_group(to_tell, mask, data, data_is, cookie,
                                     file_name, &iter_info);
 
                 if (ret && (mask & ALL_FSNOTIFY_PERM_EVENTS))
                         goto out;
 
-                if (iter_info.report_mask & FSNOTIFY_OBJ_TYPE_INODE_FL)
-                        iter_info.inode_mark =
-                                fsnotify_next_mark(iter_info.inode_mark);
-
-                if (iter_info.report_mask & FSNOTIFY_OBJ_TYPE_VFSMOUNT_FL)
-                        iter_info.vfsmount_mark =
-                                fsnotify_next_mark(iter_info.vfsmount_mark);
+                fsnotify_iter_next(&iter_info);
         }
         ret = 0;
 out: