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Revision 809b1e4945774c9ec5619a8f4e2189b7b3833c0c authored by Hannes Reinecke on 21 January 2021, 17:50:56 UTC, committed by Mike Snitzer on 21 January 2021, 20:06:45 UTC 
dm: avoid filesystem lookup in dm_get_dev_t()
 
This reverts commit
644bda6f3460 ("dm table: fall back to getting device using name_to_dev_t()")

dm_get_dev_t() is just used to convert an arbitrary 'path' string
into a dev_t. It doesn't presume that the device is present; that
check will be done later, as the only caller is dm_get_device(),
which does a dm_get_table_device() later on, which will properly
open the device.

So if the path string already _is_ in major:minor representation
we can convert it directly, avoiding a recursion into the filesystem
to lookup the block device.

This avoids a hang in multipath_message() when the filesystem is
inaccessible.

Fixes: 644bda6f3460 ("dm table: fall back to getting device using name_to_dev_t()")
Cc: stable@vger.kernel.org
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
1 parent 004b8ae
Raw File
lock_events.h 
/* SPDX-License-Identifier: GPL-2.0 */
/*
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * Authors: Waiman Long <longman@redhat.com>
 */

#ifndef __LOCKING_LOCK_EVENTS_H
#define __LOCKING_LOCK_EVENTS_H

enum lock_events {

#include "lock_events_list.h"

	lockevent_num,	/* Total number of lock event counts */
	LOCKEVENT_reset_cnts = lockevent_num,
};

#ifdef CONFIG_LOCK_EVENT_COUNTS
/*
 * Per-cpu counters
 */
DECLARE_PER_CPU(unsigned long, lockevents[lockevent_num]);

/*
 * Increment the statistical counters. use raw_cpu_inc() because of lower
 * overhead and we don't care if we loose the occasional update.
 */
static inline void __lockevent_inc(enum lock_events event, bool cond)
{
	if (cond)
		raw_cpu_inc(lockevents[event]);
}

#define lockevent_inc(ev)	  __lockevent_inc(LOCKEVENT_ ##ev, true)
#define lockevent_cond_inc(ev, c) __lockevent_inc(LOCKEVENT_ ##ev, c)

static inline void __lockevent_add(enum lock_events event, int inc)
{
	raw_cpu_add(lockevents[event], inc);
}

#define lockevent_add(ev, c)	__lockevent_add(LOCKEVENT_ ##ev, c)

#else  /* CONFIG_LOCK_EVENT_COUNTS */

#define lockevent_inc(ev)
#define lockevent_add(ev, c)
#define lockevent_cond_inc(ev, c)

#endif /* CONFIG_LOCK_EVENT_COUNTS */
#endif /* __LOCKING_LOCK_EVENTS_H */
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