From 876471ac6748641afd1f3e7f4ad5e49f6044ffce Mon Sep 17 00:00:00 2001
From: Tejun Heo <htejun@gmail.com>
Date: Fri, 5 Aug 2005 13:28:11 -0700
Subject: [PATCH] --- yaml --- r: 5674 b: refs/heads/master c:
 ba02508248e90a9d696aebd18b48a3290235b53c h: refs/heads/master v: v3

---
 [refs]                          |  2 +-
 trunk/drivers/block/ll_rw_blk.c | 18 +++++++++++++++---
 trunk/include/linux/blkdev.h    |  1 +
 3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/[refs] b/[refs]
index 40e29d263af3..7b494b27f86a 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: c7546f8f03f5a4fa612605b6be930234d6026860
+refs/heads/master: ba02508248e90a9d696aebd18b48a3290235b53c
diff --git a/trunk/drivers/block/ll_rw_blk.c b/trunk/drivers/block/ll_rw_blk.c
index 692a5fced76e..3c818544475e 100644
--- a/trunk/drivers/block/ll_rw_blk.c
+++ b/trunk/drivers/block/ll_rw_blk.c
@@ -719,7 +719,7 @@ struct request *blk_queue_find_tag(request_queue_t *q, int tag)
 {
 	struct blk_queue_tag *bqt = q->queue_tags;
 
-	if (unlikely(bqt == NULL || tag >= bqt->max_depth))
+	if (unlikely(bqt == NULL || tag >= bqt->real_max_depth))
 		return NULL;
 
 	return bqt->tag_index[tag];
@@ -798,6 +798,7 @@ init_tag_map(request_queue_t *q, struct blk_queue_tag *tags, int depth)
 
 	memset(tag_index, 0, depth * sizeof(struct request *));
 	memset(tag_map, 0, nr_ulongs * sizeof(unsigned long));
+	tags->real_max_depth = depth;
 	tags->max_depth = depth;
 	tags->tag_index = tag_index;
 	tags->tag_map = tag_map;
@@ -871,12 +872,23 @@ int blk_queue_resize_tags(request_queue_t *q, int new_depth)
 	if (!bqt)
 		return -ENXIO;
 
+	/*
+	 * if we already have large enough real_max_depth.  just
+	 * adjust max_depth.  *NOTE* as requests with tag value
+	 * between new_depth and real_max_depth can be in-flight, tag
+	 * map can not be shrunk blindly here.
+	 */
+	if (new_depth <= bqt->real_max_depth) {
+		bqt->max_depth = new_depth;
+		return 0;
+	}
+
 	/*
 	 * save the old state info, so we can copy it back
 	 */
 	tag_index = bqt->tag_index;
 	tag_map = bqt->tag_map;
-	max_depth = bqt->max_depth;
+	max_depth = bqt->real_max_depth;
 
 	if (init_tag_map(q, bqt, new_depth))
 		return -ENOMEM;
@@ -913,7 +925,7 @@ void blk_queue_end_tag(request_queue_t *q, struct request *rq)
 
 	BUG_ON(tag == -1);
 
-	if (unlikely(tag >= bqt->max_depth))
+	if (unlikely(tag >= bqt->real_max_depth))
 		/*
 		 * This can happen after tag depth has been reduced.
 		 * FIXME: how about a warning or info message here?
diff --git a/trunk/include/linux/blkdev.h b/trunk/include/linux/blkdev.h
index 0881b5cdee3d..19bd8e7e11bf 100644
--- a/trunk/include/linux/blkdev.h
+++ b/trunk/include/linux/blkdev.h
@@ -301,6 +301,7 @@ struct blk_queue_tag {
 	struct list_head busy_list;	/* fifo list of busy tags */
 	int busy;			/* current depth */
 	int max_depth;			/* what we will send to device */
+	int real_max_depth;		/* what the array can hold */
 	atomic_t refcnt;		/* map can be shared */
 };