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From ebff6d5c91195d37e33b7bbfb36c6cc0119aa06f Mon Sep 17 00:00:00 2001
From: Ming Lei <ming.lei@canonical.com>
Date: Tue, 5 May 2015 19:49:54 +0800
Subject: [PATCH 1/2] block: loop: convert to per-device workqueue
Documentation/workqueue.txt:
If there is dependency among multiple work items used
during memory reclaim, they should be queued to separate
wq each with WQ_MEM_RECLAIM.
Loop devices can be stacked, so we have to convert to per-device
workqueue. One example is Fedora live CD.
Fixes: b5dd2f6047ca108001328aac0e8588edd15f1778
Cc: stable@vger.kernel.org (v4.0)
Cc: Justin M. Forbes <jforbes@fedoraproject.org>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@fb.com>
---
drivers/block/loop.c | 30 ++++++++++++++----------------
drivers/block/loop.h | 1 +
2 files changed, 15 insertions(+), 16 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index d7173cb..9786aa3 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -86,8 +86,6 @@ 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,
@@ -725,6 +723,12 @@ 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;
@@ -872,6 +876,8 @@ 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.
@@ -1425,9 +1431,13 @@ 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;
@@ -1441,9 +1451,9 @@ static int loop_queue_rq(struct blk_mq_hw_ctx *hctx,
spin_unlock_irq(&lo->lo_lock);
if (need_sched)
- queue_work(loop_wq, &lo->write_work);
+ queue_work(lo->wq, &lo->write_work);
} else {
- queue_work(loop_wq, &cmd->read_work);
+ queue_work(lo->wq, &cmd->read_work);
}
return BLK_MQ_RQ_QUEUE_OK;
@@ -1455,9 +1465,6 @@ 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;
@@ -1806,13 +1813,6 @@ 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);
@@ -1850,8 +1850,6 @@ 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 301c27f..49564ed 100644
--- a/drivers/block/loop.h
+++ b/drivers/block/loop.h
@@ -54,6 +54,7 @@ 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;
--
2.4.5
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