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mirror of git://sourceware.org/git/lvm2.git synced 2024-12-14 13:34:43 +03:00
lvm2/lib/filters/filter-md.c
Peter Rajnoha cb04b84c79 scan: md metadata version 0.90 is at the end of disk
commit de28637
  scan: use full md filter when md 1.0 devices are present

missed the fact that md superblock version 0.90 also puts
metadata at the end of the device, so the full md filter
needs to be used when either 0.90 or 1.0 is present.
2018-11-29 12:35:54 -06:00

161 lines
4.5 KiB
C

/*
* Copyright (C) 2004 Luca Berra
* Copyright (C) 2004-2006 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include "base/memory/zalloc.h"
#include "lib/misc/lib.h"
#include "lib/filters/filter.h"
#include "lib/commands/toolcontext.h"
#ifdef __linux__
#define MSG_SKIPPING "%s: Skipping md component device"
/*
* The purpose of these functions is to ignore md component devices,
* e.g. if /dev/md0 is a raid1 composed of /dev/loop0 and /dev/loop1,
* lvm wants to deal with md0 and ignore loop0 and loop1. md0 should
* pass the filter, and loop0,loop1 should not pass the filter so lvm
* will ignore them.
*
* (This is assuming lvm.conf md_component_detection=1.)
*
* If lvm does *not* ignore the components, then lvm may read lvm
* labels from the component devs and potentially the md dev,
* which can trigger duplicate detection, and/or cause lvm to display
* md components as PVs rather than ignoring them.
*
* If scanning md componenents causes duplicates to be seen, then
* the lvm duplicate resolution will exclude the components.
*
* The lvm md filter has three modes:
*
* 1. look for md superblock at the start of the device
* 2. look for md superblock at the start and end of the device
* 3. use udev to detect components
*
* mode 1 will not detect and exclude components of md devices
* that use superblock version 0.9 or 1.0 which is at the end of the device.
*
* mode 2 will detect these, but mode 2 doubles the i/o done by label
* scan, since there's a read at both the start and end of every device.
*
* mode 3 is used when external_device_info_source="udev". It does
* not require any io from lvm, but this mode is not used by default
* because there have been problems getting reliable info from udev.
*
* lvm uses mode 2 when:
*
* - the command is pvcreate/vgcreate/vgextend, which format new
* devices, and if the user ran these commands on a component
* device of an md device 0.9 or 1.0, then it would cause problems.
* FIXME: this would only really need to scan the end of the
* devices being formatted, not all devices.
*
* - it sees an md device on the system using version 0.9 or 1.0.
* The point of this is just to avoid displaying md components
* from the 'pvs' command.
* FIXME: the cost (double i/o) may not be worth the benefit
* (not showing md components).
*/
/*
* Returns 0 if:
* the device is an md component and it should be ignored.
*
* Returns 1 if:
* the device is not md component and should not be ignored.
*
* The actual md device will pass this filter and should be used,
* it is the md component devices that we are trying to exclude
* that will not pass.
*/
static int _passes_md_filter(struct cmd_context *cmd, struct dev_filter *f __attribute__((unused)), struct device *dev)
{
int ret;
/*
* When md_component_dectection=0, don't even try to skip md
* components.
*/
if (!md_filtering())
return 1;
ret = dev_is_md(dev, NULL, cmd->use_full_md_check);
if (ret == -EAGAIN) {
/* let pass, call again after scan */
dev->flags |= DEV_FILTER_AFTER_SCAN;
log_debug_devs("filter md deferred %s", dev_name(dev));
return 1;
}
if (ret == 0)
return 1;
if (ret == 1) {
if (dev->ext.src == DEV_EXT_NONE)
log_debug_devs(MSG_SKIPPING, dev_name(dev));
else
log_debug_devs(MSG_SKIPPING " [%s:%p]", dev_name(dev),
dev_ext_name(dev), dev->ext.handle);
return 0;
}
if (ret < 0) {
log_debug_devs("%s: Skipping: error in md component detection",
dev_name(dev));
return 0;
}
return 1;
}
static void _destroy(struct dev_filter *f)
{
if (f->use_count)
log_error(INTERNAL_ERROR "Destroying md filter while in use %u times.", f->use_count);
free(f);
}
struct dev_filter *md_filter_create(struct cmd_context *cmd, struct dev_types *dt)
{
struct dev_filter *f;
if (!(f = zalloc(sizeof(*f)))) {
log_error("md filter allocation failed");
return NULL;
}
f->passes_filter = _passes_md_filter;
f->destroy = _destroy;
f->use_count = 0;
f->private = dt;
log_debug_devs("MD filter initialised.");
return f;
}
#else
struct dev_filter *md_filter_create(struct dev_types *dt)
{
return NULL;
}
#endif