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[PATCH 2/4] xfs: remove confusing ail cursor wrapper

To: xfs@xxxxxxxxxxx
Subject: [PATCH 2/4] xfs: remove confusing ail cursor wrapper
From: Dave Chinner <david@xxxxxxxxxxxxx>
Date: Mon, 18 Jul 2011 13:40:17 +1000
In-reply-to: <1310960419-9875-1-git-send-email-david@xxxxxxxxxxxxx>
References: <1310960419-9875-1-git-send-email-david@xxxxxxxxxxxxx>
From: Dave Chinner <dchinner@xxxxxxxxxx>

xfs_trans_ail_cursor_set() doesn't set the cursor to the current log
item, it sets it to the next item. There is already a function for
doing this - xfs_trans_ail_cursor_next() - and the _set function is
simply a two line wrapper.  Remove it and open code the setting of
the cursor in the two locations that call it to remove the
confusion.

Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
---
 fs/xfs/xfs_trans_ail.c |   50 ++++++++++++++++++-----------------------------
 1 files changed, 19 insertions(+), 31 deletions(-)

diff --git a/fs/xfs/xfs_trans_ail.c b/fs/xfs/xfs_trans_ail.c
index 9a69dc0..7908c79 100644
--- a/fs/xfs/xfs_trans_ail.c
+++ b/fs/xfs/xfs_trans_ail.c
@@ -189,20 +189,6 @@ xfs_trans_ail_cursor_init(
 }
 
 /*
- * Set the cursor to the next item, because when we look
- * up the cursor the current item may have been freed.
- */
-STATIC void
-xfs_trans_ail_cursor_set(
-       struct xfs_ail          *ailp,
-       struct xfs_ail_cursor   *cur,
-       struct xfs_log_item     *lip)
-{
-       if (lip)
-               cur->item = xfs_ail_next(ailp, lip);
-}
-
-/*
  * Get the next item in the traversal and advance the cursor.
  * If the cursor was invalidated (inidicated by a lip of 1),
  * restart the traversal.
@@ -216,7 +202,8 @@ xfs_trans_ail_cursor_next(
 
        if ((__psint_t)lip & 1)
                lip = xfs_ail_min(ailp);
-       xfs_trans_ail_cursor_set(ailp, cur, lip);
+       if (lip)
+               cur->item = xfs_ail_next(ailp, lip);
        return lip;
 }
 
@@ -272,9 +259,10 @@ xfs_trans_ail_cursor_clear(
 }
 
 /*
- * Initialise the cursor to the first item in the AIL with the given @lsn.
- * This searches the list from lowest LSN to highest. Pass a @lsn of zero
- * to initialise the cursor to the first item in the AIL.
+ * Find the first item in the AIL with the given @lsn by searching in ascending
+ * LSN order and initialise the cursor to point to the next item for a
+ * ascending traversal.  Pass a @lsn of zero to initialise the cursor to the
+ * first item in the AIL. Returns NULL if the list is empty.
  */
 xfs_log_item_t *
 xfs_trans_ail_cursor_first(
@@ -285,26 +273,24 @@ xfs_trans_ail_cursor_first(
        xfs_log_item_t          *lip;
 
        xfs_trans_ail_cursor_init(ailp, cur);
-       lip = xfs_ail_min(ailp);
-       if (lsn == 0)
+
+       if (lsn == 0) {
+               lip = xfs_ail_min(ailp);
                goto out;
+       }
 
        list_for_each_entry(lip, &ailp->xa_ail, li_ail) {
                if (XFS_LSN_CMP(lip->li_lsn, lsn) >= 0)
                        goto out;
        }
-       lip = NULL;
+       return NULL;
+
 out:
-       xfs_trans_ail_cursor_set(ailp, cur, lip);
+       if (lip)
+               cur->item = xfs_ail_next(ailp, lip);
        return lip;
 }
 
-/*
- * Initialise the cursor to the last item in the AIL with the given @lsn.
- * This searches the list from highest LSN to lowest. If there is no item with
- * the value of @lsn, then it sets the cursor to the last item with an LSN 
lower
- * than @lsn.
- */
 static struct xfs_log_item *
 __xfs_trans_ail_cursor_last(
        struct xfs_ail          *ailp,
@@ -320,8 +306,10 @@ __xfs_trans_ail_cursor_last(
 }
 
 /*
- * Initialise the cursor to the last item in the AIL with the given @lsn.
- * This searches the list from highest LSN to lowest.
+ * Find the last item in the AIL with the given @lsn by searching in descending
+ * LSN order and initialise the cursor to point to that item.  If there is no
+ * item with the value of @lsn, then it sets the cursor to the last item with 
an
+ * LSN lower than @lsn.  Returns NULL if the list is empty.
  */
 struct xfs_log_item *
 xfs_trans_ail_cursor_last(
@@ -335,7 +323,7 @@ xfs_trans_ail_cursor_last(
 }
 
 /*
- * splice the log item list into the AIL at the given LSN. We splice to the
+ * Splice the log item list into the AIL at the given LSN. We splice to the
  * tail of the given LSN to maintain insert order for push traversals. The
  * cursor is optional, allowing repeated updates to the same LSN to avoid
  * repeated traversals.
-- 
1.7.5.1

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