zfs-builds-mm/zfs-2.0.0-rc5/lib/libzutil/os/linux/zutil_device_path_os.c
2020-11-03 21:32:00 +01:00

506 lines
12 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
*/
#include <ctype.h>
#include <dirent.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/efi_partition.h>
#ifdef HAVE_LIBUDEV
#include <libudev.h>
#endif
#include <libzutil.h>
/*
* Append partition suffix to an otherwise fully qualified device path.
* This is used to generate the name the full path as its stored in
* ZPOOL_CONFIG_PATH for whole disk devices. On success the new length
* of 'path' will be returned on error a negative value is returned.
*/
int
zfs_append_partition(char *path, size_t max_len)
{
int len = strlen(path);
if ((strncmp(path, UDISK_ROOT, strlen(UDISK_ROOT)) == 0) ||
(strncmp(path, ZVOL_ROOT, strlen(ZVOL_ROOT)) == 0)) {
if (len + 6 >= max_len)
return (-1);
(void) strcat(path, "-part1");
len += 6;
} else {
if (len + 2 >= max_len)
return (-1);
if (isdigit(path[len-1])) {
(void) strcat(path, "p1");
len += 2;
} else {
(void) strcat(path, "1");
len += 1;
}
}
return (len);
}
/*
* Remove partition suffix from a vdev path. Partition suffixes may take three
* forms: "-partX", "pX", or "X", where X is a string of digits. The second
* case only occurs when the suffix is preceded by a digit, i.e. "md0p0" The
* third case only occurs when preceded by a string matching the regular
* expression "^([hsv]|xv)d[a-z]+", i.e. a scsi, ide, virtio or xen disk.
*
* caller must free the returned string
*/
char *
zfs_strip_partition(char *path)
{
char *tmp = strdup(path);
char *part = NULL, *d = NULL;
if (!tmp)
return (NULL);
if ((part = strstr(tmp, "-part")) && part != tmp) {
d = part + 5;
} else if ((part = strrchr(tmp, 'p')) &&
part > tmp + 1 && isdigit(*(part-1))) {
d = part + 1;
} else if ((tmp[0] == 'h' || tmp[0] == 's' || tmp[0] == 'v') &&
tmp[1] == 'd') {
for (d = &tmp[2]; isalpha(*d); part = ++d) { }
} else if (strncmp("xvd", tmp, 3) == 0) {
for (d = &tmp[3]; isalpha(*d); part = ++d) { }
}
if (part && d && *d != '\0') {
for (; isdigit(*d); d++) { }
if (*d == '\0')
*part = '\0';
}
return (tmp);
}
/*
* Same as zfs_strip_partition, but allows "/dev/" to be in the pathname
*
* path: /dev/sda1
* returns: /dev/sda
*
* Returned string must be freed.
*/
static char *
zfs_strip_partition_path(char *path)
{
char *newpath = strdup(path);
char *sd_offset;
char *new_sd;
if (!newpath)
return (NULL);
/* Point to "sda1" part of "/dev/sda1" */
sd_offset = strrchr(newpath, '/') + 1;
/* Get our new name "sda" */
new_sd = zfs_strip_partition(sd_offset);
if (!new_sd) {
free(newpath);
return (NULL);
}
/* Paste the "sda" where "sda1" was */
strlcpy(sd_offset, new_sd, strlen(sd_offset) + 1);
/* Free temporary "sda" */
free(new_sd);
return (newpath);
}
/*
* Strip the unwanted portion of a device path.
*/
char *
zfs_strip_path(char *path)
{
return (strrchr(path, '/') + 1);
}
/*
* Allocate and return the underlying device name for a device mapper device.
* If a device mapper device maps to multiple devices, return the first device.
*
* For example, dm_name = "/dev/dm-0" could return "/dev/sda". Symlinks to a
* DM device (like /dev/disk/by-vdev/A0) are also allowed.
*
* Returns device name, or NULL on error or no match. If dm_name is not a DM
* device then return NULL.
*
* NOTE: The returned name string must be *freed*.
*/
static char *
dm_get_underlying_path(const char *dm_name)
{
DIR *dp = NULL;
struct dirent *ep;
char *realp;
char *tmp = NULL;
char *path = NULL;
char *dev_str;
int size;
if (dm_name == NULL)
return (NULL);
/* dm name may be a symlink (like /dev/disk/by-vdev/A0) */
realp = realpath(dm_name, NULL);
if (realp == NULL)
return (NULL);
/*
* If they preface 'dev' with a path (like "/dev") then strip it off.
* We just want the 'dm-N' part.
*/
tmp = strrchr(realp, '/');
if (tmp != NULL)
dev_str = tmp + 1; /* +1 since we want the chr after '/' */
else
dev_str = tmp;
size = asprintf(&tmp, "/sys/block/%s/slaves/", dev_str);
if (size == -1 || !tmp)
goto end;
dp = opendir(tmp);
if (dp == NULL)
goto end;
/*
* Return first entry (that isn't itself a directory) in the
* directory containing device-mapper dependent (underlying)
* devices.
*/
while ((ep = readdir(dp))) {
if (ep->d_type != DT_DIR) { /* skip "." and ".." dirs */
size = asprintf(&path, "/dev/%s", ep->d_name);
break;
}
}
end:
if (dp != NULL)
closedir(dp);
free(tmp);
free(realp);
return (path);
}
/*
* Return B_TRUE if device is a device mapper or multipath device.
* Return B_FALSE if not.
*/
boolean_t
zfs_dev_is_dm(const char *dev_name)
{
char *tmp;
tmp = dm_get_underlying_path(dev_name);
if (tmp == NULL)
return (B_FALSE);
free(tmp);
return (B_TRUE);
}
/*
* By "whole disk" we mean an entire physical disk (something we can
* label, toggle the write cache on, etc.) as opposed to the full
* capacity of a pseudo-device such as lofi or did. We act as if we
* are labeling the disk, which should be a pretty good test of whether
* it's a viable device or not. Returns B_TRUE if it is and B_FALSE if
* it isn't.
*/
boolean_t
zfs_dev_is_whole_disk(const char *dev_name)
{
struct dk_gpt *label;
int fd;
if ((fd = open(dev_name, O_RDONLY | O_DIRECT)) < 0)
return (B_FALSE);
if (efi_alloc_and_init(fd, EFI_NUMPAR, &label) != 0) {
(void) close(fd);
return (B_FALSE);
}
efi_free(label);
(void) close(fd);
return (B_TRUE);
}
/*
* Lookup the underlying device for a device name
*
* Often you'll have a symlink to a device, a partition device,
* or a multipath device, and want to look up the underlying device.
* This function returns the underlying device name. If the device
* name is already the underlying device, then just return the same
* name. If the device is a DM device with multiple underlying devices
* then return the first one.
*
* For example:
*
* 1. /dev/disk/by-id/ata-QEMU_HARDDISK_QM00001 -> ../../sda
* dev_name: /dev/disk/by-id/ata-QEMU_HARDDISK_QM00001
* returns: /dev/sda
*
* 2. /dev/mapper/mpatha (made up of /dev/sda and /dev/sdb)
* dev_name: /dev/mapper/mpatha
* returns: /dev/sda (first device)
*
* 3. /dev/sda (already the underlying device)
* dev_name: /dev/sda
* returns: /dev/sda
*
* 4. /dev/dm-3 (mapped to /dev/sda)
* dev_name: /dev/dm-3
* returns: /dev/sda
*
* 5. /dev/disk/by-id/scsi-0QEMU_drive-scsi0-0-0-0-part9 -> ../../sdb9
* dev_name: /dev/disk/by-id/scsi-0QEMU_drive-scsi0-0-0-0-part9
* returns: /dev/sdb
*
* 6. /dev/disk/by-uuid/5df030cf-3cd9-46e4-8e99-3ccb462a4e9a -> ../dev/sda2
* dev_name: /dev/disk/by-uuid/5df030cf-3cd9-46e4-8e99-3ccb462a4e9a
* returns: /dev/sda
*
* Returns underlying device name, or NULL on error or no match.
*
* NOTE: The returned name string must be *freed*.
*/
char *
zfs_get_underlying_path(const char *dev_name)
{
char *name = NULL;
char *tmp;
if (dev_name == NULL)
return (NULL);
tmp = dm_get_underlying_path(dev_name);
/* dev_name not a DM device, so just un-symlinkize it */
if (tmp == NULL)
tmp = realpath(dev_name, NULL);
if (tmp != NULL) {
name = zfs_strip_partition_path(tmp);
free(tmp);
}
return (name);
}
/*
* Given a dev name like "sda", return the full enclosure sysfs path to
* the disk. You can also pass in the name with "/dev" prepended
* to it (like /dev/sda).
*
* For example, disk "sda" in enclosure slot 1:
* dev: "sda"
* returns: "/sys/class/enclosure/1:0:3:0/Slot 1"
*
* 'dev' must be a non-devicemapper device.
*
* Returned string must be freed.
*/
char *
zfs_get_enclosure_sysfs_path(const char *dev_name)
{
DIR *dp = NULL;
struct dirent *ep;
char buf[MAXPATHLEN];
char *tmp1 = NULL;
char *tmp2 = NULL;
char *tmp3 = NULL;
char *path = NULL;
size_t size;
int tmpsize;
if (dev_name == NULL)
return (NULL);
/* If they preface 'dev' with a path (like "/dev") then strip it off */
tmp1 = strrchr(dev_name, '/');
if (tmp1 != NULL)
dev_name = tmp1 + 1; /* +1 since we want the chr after '/' */
tmpsize = asprintf(&tmp1, "/sys/block/%s/device", dev_name);
if (tmpsize == -1 || tmp1 == NULL) {
tmp1 = NULL;
goto end;
}
dp = opendir(tmp1);
if (dp == NULL) {
tmp1 = NULL; /* To make free() at the end a NOP */
goto end;
}
/*
* Look though all sysfs entries in /sys/block/<dev>/device for
* the enclosure symlink.
*/
while ((ep = readdir(dp))) {
/* Ignore everything that's not our enclosure_device link */
if (strstr(ep->d_name, "enclosure_device") == NULL)
continue;
if (asprintf(&tmp2, "%s/%s", tmp1, ep->d_name) == -1 ||
tmp2 == NULL)
break;
size = readlink(tmp2, buf, sizeof (buf));
/* Did readlink fail or crop the link name? */
if (size == -1 || size >= sizeof (buf)) {
free(tmp2);
tmp2 = NULL; /* To make free() at the end a NOP */
break;
}
/*
* We got a valid link. readlink() doesn't terminate strings
* so we have to do it.
*/
buf[size] = '\0';
/*
* Our link will look like:
*
* "../../../../port-11:1:2/..STUFF../enclosure/1:0:3:0/SLOT 1"
*
* We want to grab the "enclosure/1:0:3:0/SLOT 1" part
*/
tmp3 = strstr(buf, "enclosure");
if (tmp3 == NULL)
break;
if (asprintf(&path, "/sys/class/%s", tmp3) == -1) {
/* If asprintf() fails, 'path' is undefined */
path = NULL;
break;
}
if (path == NULL)
break;
}
end:
free(tmp2);
free(tmp1);
if (dp != NULL)
closedir(dp);
return (path);
}
#ifdef HAVE_LIBUDEV
/*
* A disk is considered a multipath whole disk when:
* DEVNAME key value has "dm-"
* DM_NAME key value has "mpath" prefix
* DM_UUID key exists
* ID_PART_TABLE_TYPE key does not exist or is not gpt
*/
static boolean_t
udev_mpath_whole_disk(struct udev_device *dev)
{
const char *devname, *type, *uuid;
devname = udev_device_get_property_value(dev, "DEVNAME");
type = udev_device_get_property_value(dev, "ID_PART_TABLE_TYPE");
uuid = udev_device_get_property_value(dev, "DM_UUID");
if ((devname != NULL && strncmp(devname, "/dev/dm-", 8) == 0) &&
((type == NULL) || (strcmp(type, "gpt") != 0)) &&
(uuid != NULL)) {
return (B_TRUE);
}
return (B_FALSE);
}
/*
* Check if a disk is effectively a multipath whole disk
*/
boolean_t
is_mpath_whole_disk(const char *path)
{
struct udev *udev;
struct udev_device *dev = NULL;
char nodepath[MAXPATHLEN];
char *sysname;
boolean_t wholedisk = B_FALSE;
if (realpath(path, nodepath) == NULL)
return (B_FALSE);
sysname = strrchr(nodepath, '/') + 1;
if (strncmp(sysname, "dm-", 3) != 0)
return (B_FALSE);
if ((udev = udev_new()) == NULL)
return (B_FALSE);
if ((dev = udev_device_new_from_subsystem_sysname(udev, "block",
sysname)) == NULL) {
udev_device_unref(dev);
return (B_FALSE);
}
wholedisk = udev_mpath_whole_disk(dev);
udev_device_unref(dev);
return (wholedisk);
}
#else /* HAVE_LIBUDEV */
/* ARGSUSED */
boolean_t
is_mpath_whole_disk(const char *path)
{
return (B_FALSE);
}
#endif /* HAVE_LIBUDEV */