From e72dbc4c8452cfd4e2b8bec84751b190e27bddf7 Mon Sep 17 00:00:00 2001
From: Santosh Shilimkar <santosh.shilimkar@oracle.com>
Date: Tue, 4 Aug 2015 10:30:35 -0700
Subject: [PATCH] Revert "block: loop: convert to per-device workqueue"

Orabug: 21059915

This reverts commit 7c9da37f27a40fabe91dae40efb6117e97469326.
---
 drivers/block/loop.c | 30 ++++++++++++++++--------------
 drivers/block/loop.h |  1 -
 2 files changed, 16 insertions(+), 15 deletions(-)

diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 9786aa3f9cf2..d7173cb1ea76 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -86,6 +86,8 @@ static DEFINE_MUTEX(loop_index_mutex);
 static int max_part;
 static int part_shift;
 
+static struct workqueue_struct *loop_wq;
+
 static int transfer_xor(struct loop_device *lo, int cmd,
 			struct page *raw_page, unsigned raw_off,
 			struct page *loop_page, unsigned loop_off,
@@ -723,12 +725,6 @@ static int loop_set_fd(struct loop_device *lo, fmode_t mode,
 	size = get_loop_size(lo, file);
 	if ((loff_t)(sector_t)size != size)
 		goto out_putf;
-	error = -ENOMEM;
-	lo->wq = alloc_workqueue("kloopd%d",
-			WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0,
-			lo->lo_number);
-	if (!lo->wq)
-		goto out_putf;
 
 	error = 0;
 
@@ -876,8 +872,6 @@ static int loop_clr_fd(struct loop_device *lo)
 	lo->lo_flags = 0;
 	if (!part_shift)
 		lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
-	destroy_workqueue(lo->wq);
-	lo->wq = NULL;
 	mutex_unlock(&lo->lo_ctl_mutex);
 	/*
 	 * Need not hold lo_ctl_mutex to fput backing file.
@@ -1431,13 +1425,9 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
 		const struct blk_mq_queue_data *bd)
 {
 	struct loop_cmd *cmd = blk_mq_rq_to_pdu(bd->rq);
-	struct loop_device *lo = cmd->rq->q->queuedata;
 
 	blk_mq_start_request(bd->rq);
 
-	if (lo->lo_state != Lo_bound)
-		return -EIO;
-
 	if (cmd->rq->cmd_flags & REQ_WRITE) {
 		struct loop_device *lo = cmd->rq->q->queuedata;
 		bool need_sched = true;
@@ -1451,9 +1441,9 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
 		spin_unlock_irq(&lo->lo_lock);
 
 		if (need_sched)
-			queue_work(lo->wq, &lo->write_work);
+			queue_work(loop_wq, &lo->write_work);
 	} else {
-		queue_work(lo->wq, &cmd->read_work);
+		queue_work(loop_wq, &cmd->read_work);
 	}
 
 	return BLK_MQ_RQ_QUEUE_OK;
@@ -1465,6 +1455,9 @@ static void loop_handle_cmd(struct loop_cmd *cmd)
 	struct loop_device *lo = cmd->rq->q->queuedata;
 	int ret = -EIO;
 
+	if (lo->lo_state != Lo_bound)
+		goto failed;
+
 	if (write && (lo->lo_flags & LO_FLAGS_READ_ONLY))
 		goto failed;
 
@@ -1813,6 +1806,13 @@ static int __init loop_init(void)
 		goto misc_out;
 	}
 
+	loop_wq = alloc_workqueue("kloopd",
+			WQ_MEM_RECLAIM | WQ_HIGHPRI | WQ_UNBOUND, 0);
+	if (!loop_wq) {
+		err = -ENOMEM;
+		goto misc_out;
+	}
+
 	blk_register_region(MKDEV(LOOP_MAJOR, 0), range,
 				  THIS_MODULE, loop_probe, NULL, NULL);
 
@@ -1850,6 +1850,8 @@ static void __exit loop_exit(void)
 	blk_unregister_region(MKDEV(LOOP_MAJOR, 0), range);
 	unregister_blkdev(LOOP_MAJOR, "loop");
 
+	destroy_workqueue(loop_wq);
+
 	misc_deregister(&loop_misc);
 }
 
diff --git a/drivers/block/loop.h b/drivers/block/loop.h
index 49564edf5581..301c27f8323f 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -54,7 +54,6 @@ struct loop_device {
 	gfp_t		old_gfp_mask;
 
 	spinlock_t		lo_lock;
-	struct workqueue_struct *wq;
 	struct list_head	write_cmd_head;
 	struct work_struct	write_work;
 	bool			write_started;
-- 
2.50.1