[PATCH 3.16 044/306] dm: mark request_queue dead before destroying the DM device

[Ben Hutchings]

3.16.40-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanass...@sandisk.com>

commit 3b785fbcf81c3533772c52b717f77293099498d3 upstream.

This avoids that new requests are queued while __dm_destroy() is in
progress.

Signed-off-by: Bart Van Assche <bart.vanass...@sandisk.com>
Signed-off-by: Mike Snitzer <snit...@redhat.com>
[js: use md->queue instead of non-present helper]
Signed-off-by: Jiri Slaby <jsl...@suse.cz>
Signed-off-by: Ben Hutchings <b...@decadent.org.uk>
---
 drivers/md/dm.c | 5 +++++
 1 file changed, 5 insertions(+)

--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2407,6 +2407,7 @@ EXPORT_SYMBOL_GPL(dm_device_name);
 
 static void __dm_destroy(struct mapped_device *md, bool wait)
 {
+       struct request_queue *q = md->queue;
        struct dm_table *map;
        int srcu_idx;
 
@@ -2417,6 +2418,10 @@ static void __dm_destroy(struct mapped_d
        set_bit(DMF_FREEING, &md->flags);
        spin_unlock(&_minor_lock);
 
+       spin_lock_irq(q->queue_lock);
+       queue_flag_set(QUEUE_FLAG_DYING, q);
+       spin_unlock_irq(q->queue_lock);
+
        /*
         * Take suspend_lock so that presuspend and postsuspend methods
         * do not race with internal suspend.