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lvm2/lib/device/dev-luks.c
Peter Rajnoha c08c564e21 Use new dev_open_readonly fn to prevent opening devices for read-write when not necessary.
Before, we used vg_write_lock_held call to determnine the way a device is
opened. Unfortunately, this opened many devices in RW mode when it was not
really necessary. With the OPTIONS+="watch" rule used in the udev rules,
this could fire numerous events while closing such devices (and it caused
useless scans from within udev rules in return).

A common bug we hit with this was with the lvremove command which was unable
to remove the LV since it was being opened from within the udev rules. This
patch should minimize such situations (at least with respect to LVM handling
of devices).

Though there's still a possibility someone will open a device 'outside' in
parallel and fire the event based on the watch rule when closing a device
once opened for RW.
2011-05-28 09:48:14 +00:00

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C

/*
* Copyright (C) 2010 Red Hat, Inc. All rights reserved.
*
* This file is part of LVM2.
*
* This copyrighted material is made available to anyone wishing to use,
* modify, copy, or redistribute it subject to the terms and conditions
* of the GNU Lesser General Public License v.2.1.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include "lib.h"
#include "metadata.h"
#define LUKS_SIGNATURE "LUKS\xba\xbe"
#define LUKS_SIGNATURE_SIZE 6
int dev_is_luks(struct device *dev, uint64_t *signature)
{
char buf[LUKS_SIGNATURE_SIZE];
int ret = -1;
if (!dev_open_readonly(dev)) {
stack;
return -1;
}
*signature = 0;
if (!dev_read(dev, 0, LUKS_SIGNATURE_SIZE, buf))
goto_out;
ret = memcmp(buf, LUKS_SIGNATURE, LUKS_SIGNATURE_SIZE) ? 0 : 1;
out:
if (!dev_close(dev))
stack;
return ret;
}