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lvm2/lib/filters/filter-mpath.c

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/*
* Copyright (C) 2011 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
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*/
#include "base/memory/zalloc.h"
#include "lib/misc/lib.h"
#include "lib/filters/filter.h"
#include "lib/activate/activate.h"
#ifdef UDEV_SYNC_SUPPORT
#include <libudev.h>
#include "lib/device/dev-ext-udev-constants.h"
#endif
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#ifdef __linux__
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#include <dirent.h>
#define MPATH_PREFIX "mpath-"
static const char *_get_sysfs_name(struct device *dev)
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{
const char *name;
if (!(name = strrchr(dev_name(dev), '/'))) {
log_error("Cannot find '/' in device name.");
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return NULL;
}
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name++;
if (!*name) {
log_error("Device name is not valid.");
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return NULL;
}
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return name;
}
static const char *_get_sysfs_name_by_devt(const char *sysfs_dir, dev_t devno,
char *buf, size_t buf_size)
{
const char *name;
char path[PATH_MAX];
int size;
if (dm_snprintf(path, sizeof(path), "%s/dev/block/%d:%d", sysfs_dir,
(int) MAJOR(devno), (int) MINOR(devno)) < 0) {
log_error("Sysfs path string is too long.");
return NULL;
}
if ((size = readlink(path, buf, buf_size - 1)) < 0) {
log_sys_error("readlink", path);
return NULL;
}
buf[size] = '\0';
if (!(name = strrchr(buf, '/'))) {
log_error("Cannot find device name in sysfs path.");
return NULL;
}
name++;
return name;
}
static int _get_sysfs_string(const char *path, char *buffer, int max_size)
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{
FILE *fp;
int r = 0;
if (!(fp = fopen(path, "r"))) {
log_sys_error("fopen", path);
return 0;
}
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if (!fgets(buffer, max_size, fp))
log_sys_error("fgets", path);
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else
r = 1;
if (fclose(fp))
log_sys_error("fclose", path);
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return r;
}
static int _get_sysfs_get_major_minor(const char *sysfs_dir, const char *kname, int *major, int *minor)
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{
char path[PATH_MAX], buffer[64];
if (dm_snprintf(path, sizeof(path), "%s/block/%s/dev", sysfs_dir, kname) < 0) {
log_error("Sysfs path string is too long.");
return 0;
}
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if (!_get_sysfs_string(path, buffer, sizeof(buffer)))
return_0;
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if (sscanf(buffer, "%d:%d", major, minor) != 2) {
log_error("Failed to parse major minor from %s", buffer);
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return 0;
}
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return 1;
}
static int _get_parent_mpath(const char *dir, char *name, int max_size)
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{
struct dirent *d;
DIR *dr;
int r = 0;
if (!(dr = opendir(dir))) {
log_sys_error("opendir", dir);
return 0;
}
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*name = '\0';
while ((d = readdir(dr))) {
if (!strcmp(d->d_name, ".") || !strcmp(d->d_name, ".."))
continue;
/* There should be only one holder if it is multipath */
if (*name) {
r = 0;
break;
}
strncpy(name, d->d_name, max_size);
r = 1;
}
if (closedir(dr))
log_sys_error("closedir", dir);
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return r;
}
#ifdef UDEV_SYNC_SUPPORT
static int _udev_dev_is_mpath(struct device *dev)
{
const char *value;
struct dev_ext *ext;
if (!(ext = dev_ext_get(dev)))
return_0;
value = udev_device_get_property_value((struct udev_device *)ext->handle, DEV_EXT_UDEV_BLKID_TYPE);
if (value && !strcmp(value, DEV_EXT_UDEV_BLKID_TYPE_MPATH))
return 1;
value = udev_device_get_property_value((struct udev_device *)ext->handle, DEV_EXT_UDEV_MPATH_DEVICE_PATH);
if (value && !strcmp(value, "1"))
return 1;
return 0;
}
#else
static int _udev_dev_is_mpath(struct device *dev)
{
return 0;
}
#endif
static int _native_dev_is_mpath(struct dev_filter *f, struct device *dev)
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{
struct dev_types *dt = (struct dev_types *) f->private;
const char *part_name, *name;
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struct stat info;
char path[PATH_MAX], parent_name[PATH_MAX];
const char *sysfs_dir = dm_sysfs_dir();
int major = MAJOR(dev->dev);
int minor = MINOR(dev->dev);
dev_t primary_dev;
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/* Limit this filter only to SCSI devices */
if (!major_is_scsi_device(dt, MAJOR(dev->dev)))
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return 0;
switch (dev_get_primary_dev(dt, dev, &primary_dev)) {
case 2: /* The dev is partition. */
part_name = dev_name(dev); /* name of original dev for log_debug msg */
if (!(name = _get_sysfs_name_by_devt(sysfs_dir, primary_dev, parent_name, sizeof(parent_name))))
return_0;
log_debug_devs("%s: Device is a partition, using primary "
"device %s for mpath component detection",
part_name, name);
break;
case 1: /* The dev is already a primary dev. Just continue with the dev. */
if (!(name = _get_sysfs_name(dev)))
return_0;
break;
default: /* 0, error. */
log_error("Failed to get primary device for %d:%d.", major, minor);
return 0;
}
if (dm_snprintf(path, sizeof(path), "%s/block/%s/holders", sysfs_dir, name) < 0) {
log_error("Sysfs path to check mpath is too long.");
return 0;
}
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/* also will filter out partitions */
if (stat(path, &info))
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return 0;
if (!S_ISDIR(info.st_mode)) {
log_error("Path %s is not a directory.", path);
return 0;
}
if (!_get_parent_mpath(path, parent_name, sizeof(parent_name)))
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return 0;
if (!_get_sysfs_get_major_minor(sysfs_dir, parent_name, &major, &minor))
return_0;
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if (major != dt->device_mapper_major)
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return 0;
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return lvm_dm_prefix_check(major, minor, MPATH_PREFIX);
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}
static int _dev_is_mpath(struct dev_filter *f, struct device *dev)
{
if (dev->ext.src == DEV_EXT_NONE)
return _native_dev_is_mpath(f, dev);
if (dev->ext.src == DEV_EXT_UDEV)
return _udev_dev_is_mpath(dev);
log_error(INTERNAL_ERROR "Missing hook for mpath recognition "
"using external device info source %s", dev_ext_name(dev));
return 0;
}
#define MSG_SKIPPING "%s: Skipping mpath component device"
static int _ignore_mpath(struct cmd_context *cmd, struct dev_filter *f, struct device *dev, const char *use_filter_name)
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{
if (_dev_is_mpath(f, dev) == 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);
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return 0;
}
return 1;
}
static void _destroy(struct dev_filter *f)
{
if (f->use_count)
log_error(INTERNAL_ERROR "Destroying mpath filter while in use %u times.", f->use_count);
free(f);
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}
struct dev_filter *mpath_filter_create(struct dev_types *dt)
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{
const char *sysfs_dir = dm_sysfs_dir();
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struct dev_filter *f;
if (!*sysfs_dir) {
log_verbose("No proc filesystem found: skipping multipath filter");
return NULL;
}
if (!(f = zalloc(sizeof(*f)))) {
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log_error("mpath filter allocation failed");
return NULL;
}
f->passes_filter = _ignore_mpath;
f->destroy = _destroy;
f->use_count = 0;
f->private = dt;
f->name = "mpath";
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log_debug_devs("mpath filter initialised.");
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return f;
}
#else
struct dev_filter *mpath_filter_create(struct dev_types *dt)
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{
return NULL;
}
#endif