From 1832e93496fd47439ea36259c746ff7e7182ff72 Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@infradead.org>
Date: Sun, 5 May 2002 02:56:07 -0700
Subject: [PATCH] remove global_bufferlist_lock

This patch addresses Andrew's FIXME in buffer.c and adds a spinlock that
can be passed to the buffer list manipulation functions to the reiserfs
journal.  This obsoletes the cheks for lock beeing NULL in buffer.c and
the global_bufferlist_lock.

In addition osync_inode_list is changed to use list_for_each_prev as in 2.4
instead of a hand-crafted loop.

A little comment to the reiserfs folks:  your code would be _sooo_ much
easier to understand if you used temporary local variables for often
referenced fields..
---
 fs/buffer.c | 22 ++--------------------
 1 file changed, 2 insertions(+), 20 deletions(-)

(limited to 'fs/buffer.c')

diff --git a/fs/buffer.c b/fs/buffer.c
index 32147290aac5..e1ea3dca4687 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -48,15 +48,6 @@ static struct bh_wait_queue_head {
 	wait_queue_head_t wqh;
 } ____cacheline_aligned_in_smp bh_wait_queue_heads[1<<BH_WAIT_TABLE_ORDER];
 
-/*
- * Several of these buffer list functions are exported to filesystems,
- * so we do funny things with the spinlocking to support those
- * filesystems while still using inode->i_bufferlist_lock for
- * most applications.
- * FIXME: put a spinlock in the reiserfs journal and kill this lock.
- */
-static spinlock_t global_bufferlist_lock = SPIN_LOCK_UNLOCKED;
-
 /*
  * Debug/devel support stuff
  */
@@ -448,8 +439,6 @@ out:
 void buffer_insert_list(spinlock_t *lock,
 		struct buffer_head *bh, struct list_head *list)
 {
-	if (lock == NULL)
-		lock = &global_bufferlist_lock;
 	spin_lock(lock);
 	list_del(&bh->b_inode_buffers);
 	list_add(&bh->b_inode_buffers, list);
@@ -701,14 +690,10 @@ static int osync_buffers_list(spinlock_t *lock, struct list_head *list)
 	struct list_head *p;
 	int err = 0;
 
-	if (lock == NULL)
-		lock = &global_bufferlist_lock;
-
 	spin_lock(lock);
 repeat:
-	for (p = list->prev; 
-	     bh = BH_ENTRY(p), p != list;
-	     p = bh->b_inode_buffers.prev) {
+	list_for_each_prev(p, list) {
+		bh = BH_ENTRY(p);
 		if (buffer_locked(bh)) {
 			get_bh(bh);
 			spin_unlock(lock);
@@ -749,9 +734,6 @@ int fsync_buffers_list(spinlock_t *lock, struct list_head *list)
 	struct list_head tmp;
 	int err = 0, err2;
 
-	if (lock == NULL)
-		lock = &global_bufferlist_lock;
-	
 	INIT_LIST_HEAD(&tmp);
 
 	spin_lock(lock);
-- 
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