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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
crash_dump.c 
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/kernel.h>
#include <linux/crash_dump.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/export.h>

/*
 * stores the physical address of elf header of crash image
 *
 * Note: elfcorehdr_addr is not just limited to vmcore. It is also used by
 * is_kdump_kernel() to determine if we are booting after a panic. Hence put
 * it under CONFIG_CRASH_DUMP and not CONFIG_PROC_VMCORE.
 */
unsigned long long elfcorehdr_addr = ELFCORE_ADDR_MAX;
EXPORT_SYMBOL_GPL(elfcorehdr_addr);

/*
 * stores the size of elf header of crash image
 */
unsigned long long elfcorehdr_size;

/*
 * elfcorehdr= specifies the location of elf core header stored by the crashed
 * kernel. This option will be passed by kexec loader to the capture kernel.
 *
 * Syntax: elfcorehdr=[size[KMG]@]offset[KMG]
 */
static int __init setup_elfcorehdr(char *arg)
{
	char *end;
	if (!arg)
		return -EINVAL;
	elfcorehdr_addr = memparse(arg, &end);
	if (*end == '@') {
		elfcorehdr_size = elfcorehdr_addr;
		elfcorehdr_addr = memparse(end + 1, &end);
	}
	return end > arg ? 0 : -EINVAL;
}
early_param("elfcorehdr", setup_elfcorehdr);
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