Merge pull request #17431 from msekletar/udev-link-update-race

udev: make algorithm that selects highest priority devlink less susceptible to race conditions

src/basic/stat-util.c

@@ -408,7 +408,8 @@ bool stat_inode_unmodified(const struct stat *a, const struct stat *b) {
         return a && b &&
                 (a->st_mode & S_IFMT) != 0 && /* We use the check for .st_mode if the structure was ever initialized */
                 ((a->st_mode ^ b->st_mode) & S_IFMT) == 0 &&  /* same inode type */
-                a->st_mtime == b->st_mtime &&
+                a->st_mtim.tv_sec == b->st_mtim.tv_sec &&
+                a->st_mtim.tv_nsec == b->st_mtim.tv_nsec &&
                 (!S_ISREG(a->st_mode) || a->st_size == b->st_size) && /* if regular file, compare file size */
                 a->st_dev == b->st_dev &&
                 a->st_ino == b->st_ino &&

src/core/socket.c

@@ -1710,6 +1710,8 @@ static int socket_open_fds(Socket *_s) {
                         _cleanup_free_ char *ep = NULL;
 
                         ep = path_make_absolute("ep0", p->path);
+                        if (!ep)
+                                return -ENOMEM;
 
                         p->fd = usbffs_address_create(ep);
                         if (p->fd < 0)

src/libsystemd/sd-bus/bus-error.c

@@ -581,7 +581,7 @@ const char *bus_error_message(const sd_bus_error *e, int error) {
                         return e->message;
         }
 
-        return strerror_safe(abs(error));
+        return strerror_safe(error);
 }
 
 static bool map_ok(const sd_bus_error_map *map) {

src/udev/udev-builtin-net_setup_link.c

@@ -19,7 +19,10 @@ static int builtin_net_setup_link(sd_device *dev, int argc, char **argv, bool te
                 return log_device_error_errno(dev, SYNTHETIC_ERRNO(EINVAL), "This program takes no arguments.");
 
         r = link_get_driver(ctx, dev, &driver);
-        if (r >= 0)
+        if (r < 0)
+                log_device_full_errno(dev, r == -EOPNOTSUPP ? LOG_DEBUG : LOG_WARNING,
+                                      r, "Failed to query device driver: %m");
+        else
                 udev_builtin_add_property(dev, test, "ID_NET_DRIVER", driver);
 
         r = link_config_get(ctx, dev, &link);

src/udev/udev-event.c

@@ -1041,6 +1041,13 @@ int udev_event_execute_rules(UdevEvent *event,
         if (r < 0)
                 return log_device_debug_errno(dev, r, "Failed to update database under /run/udev/data/: %m");
 
+        /* Yes, we run update_devnode() twice, because in the first invocation, that is before update of udev database,
+         * it could happen that two contenders are replacing each other's symlink. Hence we run it again to make sure
+         * symlinks point to devices that claim them with the highest priority. */
+        r = update_devnode(event);
+        if (r < 0)
+                return r;
+
         device_set_is_initialized(dev);
 
         return 0;

src/udev/udev-node.c

@@ -20,12 +20,15 @@
 #include "path-util.h"
 #include "selinux-util.h"
 #include "smack-util.h"
+#include "stat-util.h"
 #include "stdio-util.h"
 #include "string-util.h"
 #include "strxcpyx.h"
 #include "udev-node.h"
 #include "user-util.h"
 
+#define LINK_UPDATE_MAX_RETRIES 128
+
 static int node_symlink(sd_device *dev, const char *node, const char *slink) {
         _cleanup_free_ char *slink_dirname = NULL, *target = NULL;
         const char *id_filename, *slink_tmp;
@@ -99,7 +102,9 @@ static int node_symlink(sd_device *dev, const char *node, const char *slink) {
         if (rename(slink_tmp, slink) < 0) {
                 r = log_device_error_errno(dev, errno, "Failed to rename '%s' to '%s': %m", slink_tmp, slink);
                 (void) unlink(slink_tmp);
-        }
+        } else
+                /* Tell caller that we replaced already existing symlink. */
+                r = 1;
 
         return r;
 }
@@ -192,7 +197,7 @@ static int link_update(sd_device *dev, const char *slink, bool add) {
         _cleanup_free_ char *target = NULL, *filename = NULL, *dirname = NULL;
         char name_enc[PATH_MAX];
         const char *id_filename;
-        int r;
+        int i, r, retries;
 
         assert(dev);
         assert(slink);
@@ -212,14 +217,6 @@ static int link_update(sd_device *dev, const char *slink, bool add) {
         if (!add && unlink(filename) == 0)
                 (void) rmdir(dirname);
 
-        r = link_find_prioritized(dev, add, dirname, &target);
-        if (r < 0) {
-                log_device_debug(dev, "No reference left, removing '%s'", slink);
-                if (unlink(slink) == 0)
-                        (void) rmdir_parents(slink, "/");
-        } else
-                (void) node_symlink(dev, target, slink);
-
         if (add)
                 do {
                         _cleanup_close_ int fd = -1;
@@ -232,7 +229,49 @@ static int link_update(sd_device *dev, const char *slink, bool add) {
                                 r = -errno;
                 } while (r == -ENOENT);
 
-        return r;
+        /* If the database entry is not written yet we will just do one iteration and possibly wrong symlink
+         * will be fixed in the second invocation. */
+        retries = sd_device_get_is_initialized(dev) > 0 ? LINK_UPDATE_MAX_RETRIES : 1;
+
+        for (i = 0; i < retries; i++) {
+                struct stat st1 = {}, st2 = {};
+
+                r = stat(dirname, &st1);
+                if (r < 0 && errno != ENOENT)
+                        return -errno;
+
+                r = link_find_prioritized(dev, add, dirname, &target);
+                if (r == -ENOENT) {
+                        log_device_debug(dev, "No reference left, removing '%s'", slink);
+                        if (unlink(slink) == 0)
+                                (void) rmdir_parents(slink, "/");
+
+                        break;
+                } else if (r < 0)
+                        return log_device_error_errno(dev, r, "Failed to determine highest priority symlink: %m");
+
+                r = node_symlink(dev, target, slink);
+                if (r < 0) {
+                        (void) unlink(filename);
+                        break;
+                } else if (r == 1)
+                        /* We have replaced already existing symlink, possibly there is some other device trying
+                         * to claim the same symlink. Let's do one more iteration to give us a chance to fix
+                         * the error if other device actually claims the symlink with higher priority. */
+                        continue;
+
+                /* Skip the second stat() if the first failed, stat_inode_unmodified() would return false regardless. */
+                if ((st1.st_mode & S_IFMT) != 0) {
+                        r = stat(dirname, &st2);
+                        if (r < 0 && errno != ENOENT)
+                                return -errno;
+
+                        if (stat_inode_unmodified(&st1, &st2))
+                                break;
+                }
+        }
+
+        return i < LINK_UPDATE_MAX_RETRIES ? 0 : -ELOOP;
 }
 
 int udev_node_update_old_links(sd_device *dev, sd_device *dev_old) {
@@ -451,8 +490,11 @@ int udev_node_add(sd_device *dev, bool apply,
         (void) node_symlink(dev, devnode, filename);
 
         /* create/update symlinks, add symlinks to name index */
-        FOREACH_DEVICE_DEVLINK(dev, devlink)
-                (void) link_update(dev, devlink, true);
+        FOREACH_DEVICE_DEVLINK(dev, devlink) {
+                r = link_update(dev, devlink, true);
+                if (r < 0)
+                        log_device_info_errno(dev, r, "Failed to update device symlinks: %m");
+        }
 
         return 0;
 }
@@ -465,8 +507,11 @@ int udev_node_remove(sd_device *dev) {
         assert(dev);
 
         /* remove/update symlinks, remove symlinks from name index */
-        FOREACH_DEVICE_DEVLINK(dev, devlink)
-                (void) link_update(dev, devlink, false);
+        FOREACH_DEVICE_DEVLINK(dev, devlink) {
+                r = link_update(dev, devlink, false);
+                if (r < 0)
+                        log_device_info_errno(dev, r, "Failed to update device symlinks: %m");
+        }
 
         r = xsprintf_dev_num_path_from_sd_device(dev, &filename);
         if (r < 0)

test/sd-script.py

@@ -0,0 +1,342 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: LGPL-2.1+
+#
+# sd-script.py: create LOTS of sd device entries in fake sysfs
+#
+# (C) 2018 Martin Wilck, SUSE Linux GmbH
+#
+# Run after sys-script.py
+# Usage: sd-script.py <directory> <num>
+# <num> is the number of device nodes (disks + partititions)
+# to create in addition to what sys-script.py already did.
+# The script can be run several times in a row if <num> is increased,
+# adding yet more device entries.
+# Tested up to 1000 entries, more are possible.
+# Note that sys-script.py already creates 10 sd device nodes
+# (sda+sdb and partitions). This script starts with sdc.
+
+import re
+import os
+import errno
+import sys
+
+def d(path, mode):
+    os.mkdir(path, mode)
+
+def l(path, src):
+    os.symlink(src, path)
+
+def f(path, mode, contents):
+    with open(path, "wb") as f:
+        f.write(contents)
+    os.chmod(path, mode)
+
+class SD(object):
+
+    sd_major = [8] + list(range(65, 72)) + list(range(128, 136))
+    _name_re = re.compile(r'sd(?P<f>[a-z]*)$')
+
+    def _init_from_name(self, name):
+        mt = self._name_re.match(name)
+        if mt is None:
+            raise RuntimeError("invalid name %s" % name)
+        nm = mt.group("f")
+        base = 1
+        ls = nm[-1]
+        nm = nm[:-1]
+        n = base * (ord(ls)-ord('a'))
+        while len(nm) > 0:
+            ls = nm[-1]
+            nm = nm[:-1]
+            base *= 26
+            n += base * (1 + ord(ls)-ord('a'))
+        self._num = n
+
+    def _init_from_dev(self, dev):
+        maj, min = dev.split(":")
+        maj = self.sd_major.index(int(maj, 10))
+        min = int(min, 10)
+        num = int(min / 16)
+        self._num = 16*maj + num%16 + 256*int(num/16)
+
+    @staticmethod
+    def _disk_num(a, b):
+        n = ord(a)-ord('a')
+        if b != '':
+            n = 26 * (n+1) + ord(b)-ord('a')
+        return n
+
+    @staticmethod
+    def _get_major(n):
+        return SD.sd_major[(n%256)//16]
+    @staticmethod
+    def _get_minor(n):
+        return 16 * (n % 16 + 16 * n//256)
+
+    @staticmethod
+    def _get_name(n):
+        # see sd_format_disk_name() (sd.c)
+        s = chr(n % 26 + ord('a'))
+        n = n // 26 - 1
+        while n >= 0:
+            s = chr(n % 26 + ord('a')) + s
+            n = n // 26 - 1
+        return "sd" + s
+
+    @staticmethod
+    def _get_dev_t(n):
+        maj = SD._get_major(n)
+        min = SD._get_minor(n)
+        return (maj << 20) + min
+
+    def __init__(self, arg):
+        if type(arg) is type(0):
+            self._num = arg
+        elif arg.startswith("sd"):
+            self._init_from_name(arg)
+        else:
+            self._init_from_dev(arg)
+
+    def __cmp__(self, other):
+        return cmp(self._num, other._num)
+
+    def __hash__(self):
+        return hash(self._num)
+
+    def __str__(self):
+        return "%s/%s" % (
+            self.devstr(),
+            self._get_name(self._num))
+
+    def major(self):
+        return self._get_major(self._num)
+
+    def minor(self):
+        return self._get_minor(self._num)
+
+    def devstr(self):
+        return "%d:%d" % (self._get_major(self._num),
+                          self._get_minor(self._num))
+
+    def namestr(self):
+        return self._get_name(self._num)
+
+    def longstr(self):
+        return "%d\t%s\t%s\t%08x" % (self._num,
+                                     self.devstr(),
+                                     self.namestr(),
+                                     self._get_dev_t(self._num))
+
+class MySD(SD):
+    def subst(self, first_sg):
+        disk = {
+            "lun": self._num,
+            "major": self.major(),
+            "devnode": self.namestr(),
+            "disk_minor": self.minor(),
+            "sg_minor": first_sg + self._num,
+        }
+        return disk
+
+disk_template = r"""\
+l('sys/bus/scsi/drivers/sd/7:0:0:{lun}', '../../../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}')
+l('sys/bus/scsi/devices/7:0:0:{lun}', '../../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}')
+l('sys/dev/char/254:{sg_minor}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}')
+l('sys/dev/char/21:{sg_minor}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}')
+l('sys/class/scsi_disk/7:0:0:{lun}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}')
+l('sys/class/scsi_generic/sg{sg_minor}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}')
+l('sys/class/bsg/7:0:0:{lun}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}')
+l('sys/class/scsi_device/7:0:0:{lun}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device/7:0:0:{lun}')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/generic', 'scsi_generic/sg{sg_minor}')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/subsystem', '../../../../../../../../../bus/scsi')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/driver', '../../../../../../../../../bus/scsi/drivers/sd')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/iodone_cnt', 0o644, b'0xc3\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/device_blocked', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/max_sectors', 0o644, b'240\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/modalias', 0o644, b'scsi:t-0x00\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_level', 0o644, b'3\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/queue_depth', 0o644, b'1\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/rev', 0o644, b'1.00\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/type', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/iocounterbits', 0o644, b'32\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/vendor', 0o644, b'Generic \n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/state', 0o644, b'running\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/queue_type', 0o644, b'none\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/iorequest_cnt', 0o644, b'0xc3\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/evt_media_change', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/model', 0o644, b'USB Flash Drive \n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/ioerr_cnt', 0o644, b'0x2\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/uevent', 0o644, b'''DEVTYPE=scsi_device
+DRIVER=sd
+MODALIAS=scsi:t-0x00
+''')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/timeout', 0o644, b'60\n')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk', 0o755)
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/subsystem', '../../../../../../../../../../../class/scsi_disk')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/device', '../../../7:0:0:{lun}')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/app_tag_own', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/FUA', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/cache_type', 0o644, b'write through\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/protection_type', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/manage_start_stop', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/allow_restart', 0o644, b'1\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/uevent', 0o644, b'')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/power', 0o755)
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_disk/7:0:0:{lun}/power/wakeup', 0o644, b'\n')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/power', 0o755)
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/power/wakeup', 0o644, b'\n')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic', 0o755)
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}/subsystem', '../../../../../../../../../../../class/scsi_generic')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}/device', '../../../7:0:0:{lun}')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}/dev', 0o644, b'21:{sg_minor}\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}/uevent', 0o644, b'''MAJOR=21
+MINOR={sg_minor}
+''')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}/power', 0o755)
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_generic/sg{sg_minor}/power/wakeup', 0o644, b'\n')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg', 0o755)
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}/subsystem', '../../../../../../../../../../../class/bsg')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}/device', '../../../7:0:0:{lun}')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}/dev', 0o644, b'254:{sg_minor}\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}/uevent', 0o644, b'''MAJOR=254
+MINOR={sg_minor}
+''')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}/power', 0o755)
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/bsg/7:0:0:{lun}/power/wakeup', 0o644, b'\n')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block', 0o755)
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device', 0o755)
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device/7:0:0:{lun}', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device/7:0:0:{lun}/subsystem', '../../../../../../../../../../../class/scsi_device')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device/7:0:0:{lun}/device', '../../../7:0:0:{lun}')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device/7:0:0:{lun}/uevent', 0o644, b'')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device/7:0:0:{lun}/power', 0o755)
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/scsi_device/7:0:0:{lun}/power/wakeup', 0o644, b'\n')
+l('sys/dev/block/{major}:{disk_minor}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}')
+l('sys/class/block/{devnode}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}')
+l('sys/block/{devnode}', '../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/subsystem', '../../../../../../../../../../../class/block')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/bdi', '../../../../../../../../../../virtual/bdi/{major}:{disk_minor}')
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/device', '../../../7:0:0:{lun}')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/capability', 0o644, b'13\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/ro', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/make-it-fail', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/size', 0o644, b'257024\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/dev', 0o644, b'{major}:{disk_minor}\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/range', 0o644, b'16\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/removable', 0o644, b'1\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/stat', 0o644, b'     117      409     2103      272        0        0        0        0        0      194      272\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/uevent', 0o644, b'''MAJOR={major}
+MINOR={disk_minor}
+DEVTYPE=disk
+DEVNAME={devnode}
+''')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/bsg', '../../../bsg/7:0:0:{lun}')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/nr_requests', 0o644, b'128\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/nomerges', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/scheduler', 0o644, b'noop anticipatory deadline [cfq] \n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/hw_sector_size', 0o644, b'512\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/max_hw_sectors_kb', 0o644, b'120\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/read_ahead_kb', 0o644, b'128\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/max_sectors_kb', 0o644, b'120\n')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched', 0o755)
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/slice_async_rq', 0o644, b'2\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/back_seek_max', 0o644, b'16384\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/slice_sync', 0o644, b'100\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/slice_async', 0o644, b'40\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/fifo_expire_sync', 0o644, b'125\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/slice_idle', 0o644, b'8\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/back_seek_penalty', 0o644, b'2\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/fifo_expire_async', 0o644, b'250\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/queue/iosched/quantum', 0o644, b'4\n')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/power', 0o755)
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/power/wakeup', 0o644, b'\n')
+"""
+
+part_template = r"""\
+l('sys/dev/block/{major}:{part_minor}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}')
+l('sys/class/block/{devnode}{part_num}', '../../devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}')
+d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}', 0o755)
+l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}/subsystem', '../../../../../../../../../../../../class/block')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}/start', 0o644, b'32\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}/make-it-fail', 0o644, b'0\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}/size', 0o644, b'256992\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}/dev', 0o644, b'{major}:{part_minor}\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}/stat', 0o644, b'     109      392     1903      246        0        0        0        0        0      169      246\n')
+f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:{lun}/block/{devnode}/{devnode}{part_num}/uevent', 0o644, b'''MAJOR={major}
+MINOR={part_minor}
+DEVTYPE=partition
+DEVNAME={devnode}{part_num}
+''')
+"""
+
+if len(sys.argv) != 3:
+    exit("Usage: {} <target dir> <number>".format(sys.argv[0]))
+
+if not os.path.isdir(sys.argv[1]):
+    exit("Target dir {} not found".format(sys.argv[1]))
+
+def create_part_sysfs(disk, sd, prt):
+    part = disk
+    part.update ({
+        "part_num": prt,
+        "part_minor": disk["disk_minor"] + prt,
+    })
+
+    try:
+        exec(part_template.format(**part))
+    except OSError:
+        si = sys.exc_info()[1]
+        if (si.errno == errno.EEXIST):
+            print("sysfs structures for %s%d exist" % (sd.namestr(), prt))
+        else:
+            print("error for %s%d: %s" % (sd.namestr(), prt, si[1]))
+            raise
+    else:
+        print("sysfs structures for %s%d created" % (sd.namestr(), prt))
+
+def create_disk_sysfs(dsk, first_sg, n):
+    sd = MySD(dsk)
+    disk = sd.subst(first_sg)
+
+    try:
+        exec(disk_template.format(**disk))
+    except OSError:
+        si = sys.exc_info()[1]
+        if (si.errno == errno.EEXIST):
+            print("sysfs structures for %s exist" % sd.namestr())
+        elif (si.errno == errno.ENOENT):
+            print("error for %s: %s - have you run sys-script py first?" %
+                  (sd.namestr(), si.strerror))
+            return -1
+        else:
+            print("error for %s: %s" % (sd.namestr(), si.strerror))
+            raise
+    else:
+        print("sysfs structures for %s created" % sd.namestr())
+
+    n += 1
+    if n >= last:
+        return n
+
+    for prt in range(1, 16):
+        create_part_sysfs(disk, sd, prt)
+        n += 1
+        if n >= last:
+            return n
+
+    return n
+
+os.chdir(sys.argv[1])
+n = 0
+last = int(sys.argv[2])
+first_sg = 2
+for dsk in range(2, 1000):
+    n = create_disk_sysfs(dsk, first_sg, n)
+    if n >= last or n == -1:
+        break

test/sys-script.py

@@ -11677,6 +11677,7 @@ f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:
 f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb/uevent', 0o644, b'''MAJOR=8
 MINOR=16
 DEVTYPE=disk
+DEVNAME=sdb
 ''')
 d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb/queue', 0o755)
 l('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb/queue/bsg', '../../../bsg/7:0:0:0')
@@ -11709,6 +11710,7 @@ f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:
 f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb/sdb1/uevent', 0o644, b'''MAJOR=8
 MINOR=17
 DEVTYPE=partition
+DEVNAME=sdb1
 ''')
 d('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb/sdb1/power', 0o755)
 f('sys/devices/pci0000:00/0000:00:1d.7/usb5/5-1/5-1:1.0/host7/target7:0:0/7:0:0:0/block/sdb/sdb1/power/wakeup', 0o644, b'\n')
@@ -13150,6 +13152,7 @@ f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda10
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda10/uevent', 0o644, b'''MAJOR=8
 MINOR=10
 DEVTYPE=partition
+DEVNAME=sda10
 ''')
 d('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda10/power', 0o755)
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda10/power/wakeup', 0o644, b'\n')
@@ -13163,6 +13166,7 @@ f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda9/
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda9/uevent', 0o644, b'''MAJOR=8
 MINOR=9
 DEVTYPE=partition
+DEVNAME=sda9
 ''')
 d('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda9/holders', 0o755)
 l('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda9/holders/md0', '../../../../../../../../../virtual/block/md0')
@@ -13178,6 +13182,7 @@ f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda7/
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda7/uevent', 0o644, b'''MAJOR=8
 MINOR=7
 DEVTYPE=partition
+DEVNAME=sda7
 ''')
 d('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda7/power', 0o755)
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda7/power/wakeup', 0o644, b'\n')
@@ -13205,6 +13210,7 @@ f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda8/
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda8/uevent', 0o644, b'''MAJOR=8
 MINOR=8
 DEVTYPE=partition
+DEVNAME=sda8
 ''')
 d('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda8/power', 0o755)
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda8/power/wakeup', 0o644, b'\n')
@@ -13232,6 +13238,7 @@ f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda6/
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda6/uevent', 0o644, b'''MAJOR=8
 MINOR=6
 DEVTYPE=partition
+DEVNAME=sda6
 ''')
 d('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda6/power', 0o755)
 f('sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda6/power/wakeup', 0o644, b'\n')