[BLOCK] Fix bad sharing of tag busy list on queues with shared tag maps

For the locking to work, only the tag map and tag bit map may be shared
(incidentally, I was just explaining this to Nick yesterday, but I
apparently didn't review the code well enough myself). But we also share
the busy list!  The busy_list must be queue private, or we need a
block_queue_tag covering lock as well.

So we have to move the busy_list to the queue. This'll work fine, and
it'll actually also fix a problem with blk_queue_invalidate_tags() which
will invalidate tags across all shared queues. This is a bit confusing,
the low level driver should call it for each queue seperately since
otherwise you cannot kill tags on just a single queue for eg a hard
drive that stops responding. Since the function has no callers
currently, it's not an issue.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/include/linux/blkdev.h b/include/linux/blkdev.h
index bbf906a0b419..8396db24d019 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -341,7 +341,6 @@ enum blk_queue_state {
 struct blk_queue_tag {
 	struct request **tag_index;	/* map of busy tags */
 	unsigned long *tag_map;		/* bit map of free/busy tags */
-	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 */
@@ -435,6 +434,7 @@ struct request_queue
 	unsigned int		dma_alignment;
 
 	struct blk_queue_tag	*queue_tags;
+	struct list_head	tag_busy_list;
 
 	unsigned int		nr_sorted;
 	unsigned int		in_flight;