quota: add dqi_dirty_list description to comment of Dquot List Management
Actually there are four lists for dquot management, so add
the description of dqui_dirty_list to comment.
Signed-off-by: Chengguang Xu <cgxu519@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index 9ad72ea..f9b8602 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -223,9 +223,9 @@ static void put_quota_format(struct quota_format_type *fmt)
/*
* Dquot List Management:
- * The quota code uses three lists for dquot management: the inuse_list,
- * free_dquots, and dquot_hash[] array. A single dquot structure may be
- * on all three lists, depending on its current state.
+ * The quota code uses four lists for dquot management: the inuse_list,
+ * free_dquots, dqi_dirty_list, and dquot_hash[] array. A single dquot
+ * structure may be on some of those lists, depending on its current state.
*
* All dquots are placed to the end of inuse_list when first created, and this
* list is used for invalidate operation, which must look at every dquot.
@@ -236,6 +236,11 @@ static void put_quota_format(struct quota_format_type *fmt)
* dqstats.free_dquots gives the number of dquots on the list. When
* dquot is invalidated it's completely released from memory.
*
+ * Dirty dquots are added to the dqi_dirty_list of quota_info when mark
+ * dirtied, and this list is searched when writing dirty dquots back to
+ * quota file. Note that some filesystems do dirty dquot tracking on their
+ * own (e.g. in a journal) and thus don't use dqi_dirty_list.
+ *
* Dquots with a specific identity (device, type and id) are placed on
* one of the dquot_hash[] hash chains. The provides an efficient search
* mechanism to locate a specific dquot.