1 files changed, 29 insertions, 1 deletions

diff --git a/include/linux/gfs2_ondisk.h b/include/linux/gfs2_ondisk.h
index a44a6a078f0a..c3c19f926e6f 100644
--- a/include/linux/gfs2_ondisk.h
+++ b/include/linux/gfs2_ondisk.h
@@ -170,6 +170,33 @@ struct gfs2_rgrp {
 };
 
 /*
+ * quota linked list: user quotas and group quotas form two separate 
+ * singly linked lists. ll_next stores uids or gids of next quotas in the 
+ * linked list.
+
+Given the uid/gid, how to calculate the quota file offsets for the corresponding
+gfs2_quota structures on disk:
+
+for user quotas, given uid,
+offset = uid * sizeof(struct gfs2_quota);
+
+for group quotas, given gid,
+offset = (gid * sizeof(struct gfs2_quota)) + sizeof(struct gfs2_quota);
+
+
+  uid:0   gid:0       uid:12   gid:12      uid:17   gid:17     uid:5142 gid:5142
++-------+-------+    +-------+-------+    +-------+- - - -+    +- - - -+-------+
+| valid | valid | :: | valid | valid | :: | valid | inval | :: | inval | valid |
++-------+-------+    +-------+-------+    +-------+- - - -+    +- - - -+-------+
+next:12   next:12    next:17 next:5142    next:NULL                    next:NULL
+    |       |            |       |            |<-- user quota list         |
+     \______|___________/ \______|___________/         group quota list -->|
+            |                    |                                         |
+             \__________________/ \_______________________________________/
+
+*/
+
+/*
  * quota structure
  */
 
@@ -177,7 +204,8 @@ struct gfs2_quota {
         __be64 qu_limit;
         __be64 qu_warn;
         __be64 qu_value;
-        __u8 qu_reserved[64];
+        __be32 qu_ll_next; /* location of next quota in list */
+        __u8 qu_reserved[60];
 };
 
 /*