mount.py

import hashlib
import json
import logging
import datetime
import os
import re
import time

from io import StringIO
from contextlib import contextmanager
from textwrap import dedent
from IPy import IP

from teuthology.contextutil import safe_while
from teuthology.misc import get_file, write_file
from teuthology.orchestra import run
from teuthology.orchestra.run import CommandFailedError, ConnectionLostError, Raw

from tasks.cephfs.filesystem import Filesystem

log = logging.getLogger(__name__)

class CephFSMount(object):
    def __init__(self, ctx, test_dir, client_id, client_remote,
                 client_keyring_path=None, hostfs_mntpt=None,
                 cephfs_name=None, cephfs_mntpt=None, brxnet=None):
        """
        :param test_dir: Global teuthology test dir
        :param client_id: Client ID, the 'foo' in client.foo
        :param client_keyring_path: path to keyring for given client_id
        :param client_remote: Remote instance for the host where client will
                              run
        :param hostfs_mntpt: Path to directory on the FS on which Ceph FS will
                             be mounted
        :param cephfs_name: Name of Ceph FS to be mounted
        :param cephfs_mntpt: Path to directory inside Ceph FS that will be
                             mounted as root
        """
        self.mounted = False
        self.ctx = ctx
        self.test_dir = test_dir

        self._verify_attrs(client_id=client_id,
                           client_keyring_path=client_keyring_path,
                           hostfs_mntpt=hostfs_mntpt, cephfs_name=cephfs_name,
                           cephfs_mntpt=cephfs_mntpt)

        self.client_id = client_id
        self.client_keyring_path = client_keyring_path
        self.client_remote = client_remote
        if hostfs_mntpt:
            self.hostfs_mntpt = hostfs_mntpt
            self.hostfs_mntpt_dirname = os.path.basename(self.hostfs_mntpt)
        else:
            self.hostfs_mntpt = os.path.join(self.test_dir, f'mnt.{self.client_id}')
        self.cephfs_name = cephfs_name
        self.cephfs_mntpt = cephfs_mntpt

        self.fs = None

        self._netns_name = None
        self.nsid = -1
        if brxnet is None:
            self.ceph_brx_net = '192.168.0.0/16'
        else:
            self.ceph_brx_net = brxnet

        self.test_files = ['a', 'b', 'c']

        self.background_procs = []

    # This will cleanup the stale netnses, which are from the
    # last failed test cases.
    @staticmethod
    def cleanup_stale_netnses_and_bridge(remote):
        p = remote.run(args=['ip', 'netns', 'list'],
                       stdout=StringIO(), timeout=(5*60))
        p = p.stdout.getvalue().strip()

        # Get the netns name list
        netns_list = re.findall(r'ceph-ns-[^()\s][-.\w]+[^():\s]', p)

        # Remove the stale netnses
        for ns in netns_list:
            ns_name = ns.split()[0]
            args = ['sudo', 'ip', 'netns', 'delete', '{0}'.format(ns_name)]
            try:
                remote.run(args=args, timeout=(5*60), omit_sudo=False)
            except Exception:
                pass

        # Remove the stale 'ceph-brx'
        try:
            args = ['sudo', 'ip', 'link', 'delete', 'ceph-brx']
            remote.run(args=args, timeout=(5*60), omit_sudo=False)
        except Exception:
            pass

    def _parse_netns_name(self):
        self._netns_name = '-'.join(["ceph-ns",
                                     re.sub(r'/+', "-", self.mountpoint)])

    @property
    def mountpoint(self):
        if self.hostfs_mntpt == None:
            self.hostfs_mntpt = os.path.join(self.test_dir,
                                             self.hostfs_mntpt_dirname)
        return self.hostfs_mntpt

    @mountpoint.setter
    def mountpoint(self, path):
        if not isinstance(path, str):
            raise RuntimeError('path should be of str type.')
        self._mountpoint = self.hostfs_mntpt = path

    @property
    def netns_name(self):
        if self._netns_name == None:
            self._parse_netns_name()
        return self._netns_name

    @netns_name.setter
    def netns_name(self, name):
        self._netns_name = name

    def assert_that_ceph_fs_exists(self):
        output = self.client_remote.run(args='ceph fs ls', stdout=StringIO()).\
            stdout.getvalue()
        if self.cephfs_name:
            assert self.cephfs_name in output, \
                'expected ceph fs is not present on the cluster'
            log.info(f'Mounting Ceph FS {self.cephfs_name}; just confirmed its presence on cluster')
        else:
            assert 'No filesystems enabled' not in output, \
                'ceph cluster has no ceph fs, not even the default ceph fs'
            log.info('Mounting default Ceph FS; just confirmed its presence on cluster')

    def assert_and_log_minimum_mount_details(self):
        """
        Make sure we have minimum details required for mounting. Ideally, this
        method should be called at the beginning of the mount method.
        """
        if not self.client_id or not self.client_remote or \
           not self.hostfs_mntpt:
            errmsg = ('Mounting CephFS requires that at least following '
                      'details to be provided -\n'
                      '1. the client ID,\n2. the mountpoint and\n'
                      '3. the remote machine where CephFS will be mounted.\n')
            raise RuntimeError(errmsg)

        self.assert_that_ceph_fs_exists()

        log.info('Mounting Ceph FS. Following are details of mount; remember '
                 '"None" represents Python type None -')
        log.info(f'self.client_remote.hostname = {self.client_remote.hostname}')
        log.info(f'self.client.name = client.{self.client_id}')
        log.info(f'self.hostfs_mntpt = {self.hostfs_mntpt}')
        log.info(f'self.cephfs_name = {self.cephfs_name}')
        log.info(f'self.cephfs_mntpt = {self.cephfs_mntpt}')
        log.info(f'self.client_keyring_path = {self.client_keyring_path}')
        if self.client_keyring_path:
            log.info('keyring content -\n' +
                     get_file(self.client_remote, self.client_keyring_path,
                              sudo=True).decode())

    def is_mounted(self):
        return self.mounted

    def setupfs(self, name=None):
        if name is None and self.fs is not None:
            # Previous mount existed, reuse the old name
            name = self.fs.name
        self.fs = Filesystem(self.ctx, name=name)
        log.info('Wait for MDS to reach steady state...')
        self.fs.wait_for_daemons()
        log.info('Ready to start {}...'.format(type(self).__name__))

    def _create_mntpt(self):
        self.client_remote.run(args=f'mkdir -p -v {self.hostfs_mntpt}',
                               timeout=60)
        # Use 0000 mode to prevent undesired modifications to the mountpoint on
        # the local file system.
        self.client_remote.run(args=f'chmod 0000 {self.hostfs_mntpt}',
                               timeout=60)

    @property
    def _nsenter_args(self):
        return ['nsenter', f'--net=/var/run/netns/{self.netns_name}']

    def _set_filemode_on_mntpt(self):
        stderr = StringIO()
        try:
            self.client_remote.run(
                args=['sudo', 'chmod', '1777', self.hostfs_mntpt],
                stderr=stderr, timeout=(5*60))
        except CommandFailedError:
            # the client does not have write permissions in the caps it holds
            # for the Ceph FS that was just mounted.
            if 'permission denied' in stderr.getvalue().lower():
                pass

    def _setup_brx_and_nat(self):
        # The ip for ceph-brx should be
        ip = IP(self.ceph_brx_net)[-2]
        mask = self.ceph_brx_net.split('/')[1]
        brd = IP(self.ceph_brx_net).broadcast()

        brx = self.client_remote.run(args=['ip', 'addr'], stderr=StringIO(),
                                     stdout=StringIO(), timeout=(5*60))
        brx = re.findall(r'inet .* ceph-brx', brx.stdout.getvalue())
        if brx:
            # If the 'ceph-brx' already exists, then check whether
            # the new net is conflicting with it
            _ip, _mask = brx[0].split()[1].split('/', 1)
            if _ip != "{}".format(ip) or _mask != mask:
                raise RuntimeError("Conflict with existing ceph-brx {0}, new {1}/{2}".format(brx[0].split()[1], ip, mask))

        # Setup the ceph-brx and always use the last valid IP
        if not brx:
            log.info("Setuping the 'ceph-brx' with {0}/{1}".format(ip, mask))

            self.run_shell_payload(f"""
                set -e
                sudo ip link add name ceph-brx type bridge
                sudo ip addr flush dev ceph-brx
                sudo ip link set ceph-brx up
                sudo ip addr add {ip}/{mask} brd {brd} dev ceph-brx
            """, timeout=(5*60), omit_sudo=False, cwd='/')
        
        args = "echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward"
        self.client_remote.run(args=args, timeout=(5*60), omit_sudo=False)
        
        # Setup the NAT
        p = self.client_remote.run(args=['route'], stderr=StringIO(),
                                   stdout=StringIO(), timeout=(5*60))
        p = re.findall(r'default .*', p.stdout.getvalue())
        if p == False:
            raise RuntimeError("No default gw found")
        gw = p[0].split()[7]

        self.run_shell_payload(f"""
            set -e
            sudo iptables -A FORWARD -o {gw} -i ceph-brx -j ACCEPT
            sudo iptables -A FORWARD -i {gw} -o ceph-brx -j ACCEPT
            sudo iptables -t nat -A POSTROUTING -s {ip}/{mask} -o {gw} -j MASQUERADE
        """, timeout=(5*60), omit_sudo=False, cwd='/')

    def _setup_netns(self):
        p = self.client_remote.run(args=['ip', 'netns', 'list'],
                                   stderr=StringIO(), stdout=StringIO(),
                                   timeout=(5*60)).stdout.getvalue().strip()

        # Get the netns name list
        netns_list = re.findall(r'[^()\s][-.\w]+[^():\s]', p)

        out = re.search(r"{0}".format(self.netns_name), p)
        if out is None:
            # Get an uniq nsid for the new netns
            nsid = 0
            p = self.client_remote.run(args=['ip', 'netns', 'list-id'],
                                       stderr=StringIO(), stdout=StringIO(),
                                       timeout=(5*60)).stdout.getvalue()
            while True:
                out = re.search(r"nsid {} ".format(nsid), p)
                if out is None:
                    break

                nsid += 1

            # Add one new netns and set it id
            self.run_shell_payload(f"""
                set -e
                sudo ip netns add {self.netns_name}
                sudo ip netns set {self.netns_name} {nsid}
            """, timeout=(5*60), omit_sudo=False, cwd='/')
            self.nsid = nsid;
        else:
            # The netns already exists and maybe suspended by self.kill()
            self.resume_netns();

            nsid = int(re.search(r"{0} \(id: (\d+)\)".format(self.netns_name), p).group(1))
            self.nsid = nsid;
            return

        # Get one ip address for netns
        ips = IP(self.ceph_brx_net)
        for ip in ips:
            found = False
            if ip == ips[0]:
                continue
            if ip == ips[-2]:
                raise RuntimeError("we have ran out of the ip addresses")

            for ns in netns_list:
                ns_name = ns.split()[0]
                args = ['sudo', 'ip', 'netns', 'exec', '{0}'.format(ns_name), 'ip', 'addr']
                try:
                    p = self.client_remote.run(args=args, stderr=StringIO(),
                                               stdout=StringIO(), timeout=(5*60),
                                               omit_sudo=False)
                    q = re.search("{0}".format(ip), p.stdout.getvalue())
                    if q is not None:
                        found = True
                        break
                except CommandFailedError:
                    if "No such file or directory" in p.stderr.getvalue():
                        pass
                    if "Invalid argument" in p.stderr.getvalue():
                        pass

            if found == False:
                break

        mask = self.ceph_brx_net.split('/')[1]
        brd = IP(self.ceph_brx_net).broadcast()

        log.info("Setuping the netns '{0}' with {1}/{2}".format(self.netns_name, ip, mask))

        # Setup the veth interfaces
        brxip = IP(self.ceph_brx_net)[-2]
        self.run_shell_payload(f"""
            set -e
            sudo ip link add veth0 netns {self.netns_name} type veth peer name brx.{nsid}
            sudo ip netns exec {self.netns_name} ip addr add {ip}/{mask} brd {brd} dev veth0
            sudo ip netns exec {self.netns_name} ip link set veth0 up
            sudo ip netns exec {self.netns_name} ip link set lo up
            sudo ip netns exec {self.netns_name} ip route add default via {brxip}
        """, timeout=(5*60), omit_sudo=False, cwd='/')

        # Bring up the brx interface and join it to 'ceph-brx'
        self.run_shell_payload(f"""
            set -e
            sudo ip link set brx.{nsid} up
            sudo ip link set dev brx.{nsid} master ceph-brx
        """, timeout=(5*60), omit_sudo=False, cwd='/')

    def _cleanup_netns(self):
        if self.nsid == -1:
            return
        log.info("Removing the netns '{0}'".format(self.netns_name))

        # Delete the netns and the peer veth interface
        self.run_shell_payload(f"""
            set -e
            sudo ip link set brx.{self.nsid} down
            sudo ip link delete dev brx.{self.nsid}
            sudo ip netns delete {self.netns_name}
        """, timeout=(5*60), omit_sudo=False, cwd='/')

        self.nsid = -1

    def _cleanup_brx_and_nat(self):
        brx = self.client_remote.run(args=['ip', 'addr'], stderr=StringIO(),
                                     stdout=StringIO(), timeout=(5*60))
        brx = re.findall(r'inet .* ceph-brx', brx.stdout.getvalue())
        if not brx:
            return

        # If we are the last netns, will delete the ceph-brx
        args = ['sudo', 'ip', 'link', 'show']
        p = self.client_remote.run(args=args, stdout=StringIO(),
                                   timeout=(5*60), omit_sudo=False)
        _list = re.findall(r'brx\.', p.stdout.getvalue().strip())
        if len(_list) != 0:
            return

        log.info("Removing the 'ceph-brx'")

        self.run_shell_payload("""
            set -e
            sudo ip link set ceph-brx down
            sudo ip link delete ceph-brx
        """, timeout=(5*60), omit_sudo=False, cwd='/')

        # Drop the iptables NAT rules
        ip = IP(self.ceph_brx_net)[-2]
        mask = self.ceph_brx_net.split('/')[1]

        p = self.client_remote.run(args=['route'], stderr=StringIO(),
                                   stdout=StringIO(), timeout=(5*60))
        p = re.findall(r'default .*', p.stdout.getvalue())
        if p == False:
            raise RuntimeError("No default gw found")
        gw = p[0].split()[7]
        self.run_shell_payload(f"""
            set -e
            sudo iptables -D FORWARD -o {gw} -i ceph-brx -j ACCEPT
            sudo iptables -D FORWARD -i {gw} -o ceph-brx -j ACCEPT
            sudo iptables -t nat -D POSTROUTING -s {ip}/{mask} -o {gw} -j MASQUERADE
        """, timeout=(5*60), omit_sudo=False, cwd='/')

    def setup_netns(self):
        """
        Setup the netns for the mountpoint.
        """
        log.info("Setting the '{0}' netns for '{1}'".format(self._netns_name, self.mountpoint))
        self._setup_brx_and_nat()
        self._setup_netns()

    def cleanup_netns(self):
        """
        Cleanup the netns for the mountpoint.
        """
        # We will defer cleaning the netnses and bridge until the last
        # mountpoint is unmounted, this will be a temporary work around
        # for issue#46282.

        # log.info("Cleaning the '{0}' netns for '{1}'".format(self._netns_name, self.mountpoint))
        # self._cleanup_netns()
        # self._cleanup_brx_and_nat()

    def suspend_netns(self):
        """
        Suspend the netns veth interface.
        """
        if self.nsid == -1:
            return

        log.info("Suspending the '{0}' netns for '{1}'".format(self._netns_name, self.mountpoint))

        args = ['sudo', 'ip', 'link', 'set', 'brx.{0}'.format(self.nsid), 'down']
        self.client_remote.run(args=args, timeout=(5*60), omit_sudo=False)

    def resume_netns(self):
        """
        Resume the netns veth interface.
        """
        if self.nsid == -1:
            return

        log.info("Resuming the '{0}' netns for '{1}'".format(self._netns_name, self.mountpoint))

        args = ['sudo', 'ip', 'link', 'set', 'brx.{0}'.format(self.nsid), 'up']
        self.client_remote.run(args=args, timeout=(5*60), omit_sudo=False)

    def mount(self, mntopts=[], check_status=True, **kwargs):
        """
        kwargs expects its members to be same as the arguments accepted by
        self.update_attrs().
        """
        raise NotImplementedError()

    def mount_wait(self, **kwargs):
        """
        Accepts arguments same as self.mount().
        """
        self.mount(**kwargs)
        self.wait_until_mounted()

    def umount(self):
        raise NotImplementedError()

    def umount_wait(self, force=False, require_clean=False, timeout=None):
        """

        :param force: Expect that the mount will not shutdown cleanly: kill
                      it hard.
        :param require_clean: Wait for the Ceph client associated with the
                              mount (e.g. ceph-fuse) to terminate, and
                              raise if it doesn't do so cleanly.
        :param timeout: amount of time to be waited for umount command to finish
        :return:
        """
        raise NotImplementedError()

    def _verify_attrs(self, **kwargs):
        """
        Verify that client_id, client_keyring_path, client_remote, hostfs_mntpt,
        cephfs_name, cephfs_mntpt are either type str or None.
        """
        for k, v in kwargs.items():
            if v is not None and not isinstance(v, str):
                raise RuntimeError('value of attributes should be either str '
                                   f'or None. {k} - {v}')

    def update_attrs(self, client_id=None, client_keyring_path=None,
                     client_remote=None, hostfs_mntpt=None, cephfs_name=None,
                     cephfs_mntpt=None):
        if not (client_id or client_keyring_path or client_remote or
                cephfs_name or cephfs_mntpt or hostfs_mntpt):
            return

        self._verify_attrs(client_id=client_id,
                           client_keyring_path=client_keyring_path,
                           hostfs_mntpt=hostfs_mntpt, cephfs_name=cephfs_name,
                           cephfs_mntpt=cephfs_mntpt)

        if client_id:
            self.client_id = client_id
        if client_keyring_path:
            self.client_keyring_path = client_keyring_path
        if client_remote:
            self.client_remote = client_remote
        if hostfs_mntpt:
            self.hostfs_mntpt = hostfs_mntpt
        if cephfs_name:
            self.cephfs_name = cephfs_name
        if cephfs_mntpt:
            self.cephfs_mntpt = cephfs_mntpt

    def remount(self, **kwargs):
        """
        Update mount object's attributes and attempt remount with these
        new values for these attrbiutes.

        1. Run umount_wait().
        2. Run update_attrs().
        3. Run mount().

        Accepts arguments of self.mount() and self.update_attrs() with 1
        exception: wait accepted too which can be True or False.
        """
        self.umount_wait()
        assert not self.mounted

        mntopts = kwargs.pop('mntopts', [])
        check_status = kwargs.pop('check_status', True)
        wait = kwargs.pop('wait', True)

        self.update_attrs(**kwargs)

        retval = self.mount(mntopts=mntopts, check_status=check_status)
        # avoid this scenario (again): mount command might've failed and
        # check_status might have silenced the exception, yet we attempt to
        # wait which might lead to an error.
        if retval is None and wait:
            self.wait_until_mounted()

        return retval

    def kill(self):
        """
        Suspend the netns veth interface to make the client disconnected
        from the ceph cluster
        """
        log.info('Killing connection on {0}...'.format(self.client_remote.name))
        self.suspend_netns()

    def kill_cleanup(self):
        """
        Follow up ``kill`` to get to a clean unmounted state.
        """
        log.info('Cleaning up killed connection on {0}'.format(self.client_remote.name))
        self.umount_wait(force=True)

    def cleanup(self):
        """
        Remove the mount point.

        Prerequisite: the client is not mounted.
        """
        log.info('Cleaning up mount {0}'.format(self.client_remote.name))
        stderr = StringIO()
        try:
            self.client_remote.run(args=['rmdir', '--', self.mountpoint],
                                   cwd=self.test_dir, stderr=stderr,
                                   timeout=(60*5), check_status=False)
        except CommandFailedError:
            if "no such file or directory" not in stderr.getvalue().lower():
                raise

        self.cleanup_netns()

    def wait_until_mounted(self):
        raise NotImplementedError()

    def get_keyring_path(self):
        return '/etc/ceph/ceph.client.{id}.keyring'.format(id=self.client_id)

    def get_key_from_keyfile(self):
        # XXX: don't call run_shell(), since CephFS might be unmounted.
        keyring = self.client_remote.run(
            args=['sudo', 'cat', self.client_keyring_path], stdout=StringIO(),
            omit_sudo=False).stdout.getvalue()
        for line in keyring.split('\n'):
            if line.find('key') != -1:
                return line[line.find('=') + 1 : ].strip()

    @property
    def config_path(self):
        """
        Path to ceph.conf: override this if you're not a normal systemwide ceph install
        :return: stringv
        """
        return "/etc/ceph/ceph.conf"

    @contextmanager
    def mounted_wait(self):
        """
        A context manager, from an initially unmounted state, to mount
        this, yield, and then unmount and clean up.
        """
        self.mount()
        self.wait_until_mounted()
        try:
            yield
        finally:
            self.umount_wait()

    def create_file(self, filename='testfile', dirname=None, user=None,
                    check_status=True):
        assert(self.is_mounted())

        if not os.path.isabs(filename):
            if dirname:
                if os.path.isabs(dirname):
                    path = os.path.join(dirname, filename)
                else:
                    path = os.path.join(self.hostfs_mntpt, dirname, filename)
            else:
                path = os.path.join(self.hostfs_mntpt, filename)
        else:
            path = filename

        if user:
            args = ['sudo', '-u', user, '-s', '/bin/bash', '-c', 'touch ' + path]
        else:
            args = 'touch ' + path

        return self.client_remote.run(args=args, check_status=check_status)

    def create_files(self):
        assert(self.is_mounted())

        for suffix in self.test_files:
            log.info("Creating file {0}".format(suffix))
            self.client_remote.run(args=[
                'touch', os.path.join(self.hostfs_mntpt, suffix)
            ])

    def test_create_file(self, filename='testfile', dirname=None, user=None,
                         check_status=True):
        return self.create_file(filename=filename, dirname=dirname, user=user,
                                check_status=False)

    def check_files(self):
        assert(self.is_mounted())

        for suffix in self.test_files:
            log.info("Checking file {0}".format(suffix))
            r = self.client_remote.run(args=[
                'ls', os.path.join(self.hostfs_mntpt, suffix)
            ], check_status=False)
            if r.exitstatus != 0:
                raise RuntimeError("Expected file {0} not found".format(suffix))

    def write_file(self, path, data, perms=None):
        """
        Write the given data at the given path and set the given perms to the
        file on the path.
        """
        if path.find(self.hostfs_mntpt) == -1:
            path = os.path.join(self.hostfs_mntpt, path)

        write_file(self.client_remote, path, data)

        if perms:
            self.run_shell(args=f'chmod {perms} {path}')

    def read_file(self, path):
        """
        Return the data from the file on given path.
        """
        if path.find(self.hostfs_mntpt) == -1:
            path = os.path.join(self.hostfs_mntpt, path)

        return self.run_shell(args=['cat', path]).\
            stdout.getvalue().strip()

    def create_destroy(self):
        assert(self.is_mounted())

        filename = "{0} {1}".format(datetime.datetime.now(), self.client_id)
        log.debug("Creating test file {0}".format(filename))
        self.client_remote.run(args=[
            'touch', os.path.join(self.hostfs_mntpt, filename)
        ])
        log.debug("Deleting test file {0}".format(filename))
        self.client_remote.run(args=[
            'rm', '-f', os.path.join(self.hostfs_mntpt, filename)
        ])

    def _run_python(self, pyscript, py_version='python3', sudo=False):
        args = []
        if sudo:
            args.append('sudo')
        args += ['adjust-ulimits', 'daemon-helper', 'kill', py_version, '-c', pyscript]
        return self.client_remote.run(args=args, wait=False, stdin=run.PIPE, stdout=StringIO())

    def run_python(self, pyscript, py_version='python3', sudo=False):
        p = self._run_python(pyscript, py_version, sudo=sudo)
        p.wait()
        return p.stdout.getvalue().strip()

    def run_shell(self, args, timeout=900, **kwargs):
        args = args.split() if isinstance(args, str) else args
        kwargs.pop('omit_sudo', False)
        sudo = kwargs.pop('sudo', False)
        cwd = kwargs.pop('cwd', self.mountpoint)
        stdout = kwargs.pop('stdout', StringIO())
        stderr = kwargs.pop('stderr', StringIO())

        if sudo:
            args.insert(0, 'sudo')

        return self.client_remote.run(args=args, cwd=cwd, timeout=timeout, stdout=stdout, stderr=stderr, **kwargs)

    def run_shell_payload(self, payload, **kwargs):
        return self.run_shell(["bash", "-c", Raw(f"'{payload}'")], **kwargs)

    def run_as_user(self, **kwargs):
        """
        Besides the arguments defined for run_shell() this method also
        accepts argument 'user'.
        """
        args = kwargs.pop('args')
        user = kwargs.pop('user')
        if isinstance(args, str):
            args = ['sudo', '-u', user, '-s', '/bin/bash', '-c', args]
        elif isinstance(args, list):
            cmdlist = args
            cmd = ''
            for i in cmdlist:
                cmd = cmd + i + ' '
            # get rid of extra space at the end.
            cmd = cmd[:-1]

            args = ['sudo', '-u', user, '-s', '/bin/bash', '-c', cmd]

        kwargs['args'] = args
        return self.run_shell(**kwargs)

    def run_as_root(self, **kwargs):
        """
        Accepts same arguments as run_shell().
        """
        kwargs['user'] = 'root'
        return self.run_as_user(**kwargs)

    def _verify(self, proc, retval=None, errmsg=None):
        if retval:
            msg = ('expected return value: {}\nreceived return value: '
                   '{}\n'.format(retval, proc.returncode))
            assert proc.returncode == retval, msg

        if errmsg:
            stderr = proc.stderr.getvalue().lower()
            msg = ('didn\'t find given string in stderr -\nexpected string: '
                   '{}\nreceived error message: {}\nnote: received error '
                   'message is converted to lowercase'.format(errmsg, stderr))
            assert errmsg in stderr, msg

    def negtestcmd(self, args, retval=None, errmsg=None, stdin=None,
                   cwd=None, wait=True):
        """
        Conduct a negative test for the given command.

        retval and errmsg are parameters to confirm the cause of command
        failure.
        """
        proc = self.run_shell(args=args, wait=wait, stdin=stdin, cwd=cwd,
                              check_status=False)
        self._verify(proc, retval, errmsg)
        return proc

    def negtestcmd_as_user(self, args, user, retval=None, errmsg=None,
                           stdin=None, cwd=None, wait=True):
        proc = self.run_as_user(args=args, user=user, wait=wait, stdin=stdin,
                                cwd=cwd, check_status=False)
        self._verify(proc, retval, errmsg)
        return proc

    def negtestcmd_as_root(self, args, retval=None, errmsg=None, stdin=None,
                           cwd=None, wait=True):
        proc = self.run_as_root(args=args, wait=wait, stdin=stdin, cwd=cwd,
                                check_status=False)
        self._verify(proc, retval, errmsg)
        return proc

    def open_no_data(self, basename):
        """
        A pure metadata operation
        """
        assert(self.is_mounted())

        path = os.path.join(self.hostfs_mntpt, basename)

        p = self._run_python(dedent(
            """
            f = open("{path}", 'w')
            """.format(path=path)
        ))
        p.wait()

    def open_background(self, basename="background_file", write=True):
        """
        Open a file for writing, then block such that the client
        will hold a capability.

        Don't return until the remote process has got as far as opening
        the file, then return the RemoteProcess instance.
        """
        assert(self.is_mounted())

        path = os.path.join(self.hostfs_mntpt, basename)

        if write:
            pyscript = dedent("""
                import time

                with open("{path}", 'w') as f:
                    f.write('content')
                    f.flush()
                    f.write('content2')
                    while True:
                        time.sleep(1)
                """).format(path=path)
        else:
            pyscript = dedent("""
                import time

                with open("{path}", 'r') as f:
                    while True:
                        time.sleep(1)
                """).format(path=path)

        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)

        # This wait would not be sufficient if the file had already
        # existed, but it's simple and in practice users of open_background
        # are not using it on existing files.
        self.wait_for_visible(basename)

        return rproc

    def wait_for_dir_empty(self, dirname, timeout=30):
        dirpath = os.path.join(self.hostfs_mntpt, dirname)
        with safe_while(sleep=5, tries=(timeout//5)) as proceed:
            while proceed():
                p = self.run_shell_payload(f"stat -c %h {dirpath}")
                nr_links = int(p.stdout.getvalue().strip())
                if nr_links == 2:
                    return

    def wait_for_visible(self, basename="background_file", timeout=30):
        i = 0
        while i < timeout:
            r = self.client_remote.run(args=[
                'stat', os.path.join(self.hostfs_mntpt, basename)
            ], check_status=False)
            if r.exitstatus == 0:
                log.debug("File {0} became visible from {1} after {2}s".format(
                    basename, self.client_id, i))
                return
            else:
                time.sleep(1)
                i += 1

        raise RuntimeError("Timed out after {0}s waiting for {1} to become visible from {2}".format(
            i, basename, self.client_id))

    def lock_background(self, basename="background_file", do_flock=True):
        """
        Open and lock a files for writing, hold the lock in a background process
        """
        assert(self.is_mounted())

        path = os.path.join(self.hostfs_mntpt, basename)

        script_builder = """
            import time
            import fcntl
            import struct"""
        if do_flock:
            script_builder += """
            f1 = open("{path}-1", 'w')
            fcntl.flock(f1, fcntl.LOCK_EX | fcntl.LOCK_NB)"""
        script_builder += """
            f2 = open("{path}-2", 'w')
            lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
            fcntl.fcntl(f2, fcntl.F_SETLK, lockdata)
            while True:
                time.sleep(1)
            """

        pyscript = dedent(script_builder).format(path=path)

        log.info("lock_background file {0}".format(basename))
        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)
        return rproc

    def lock_and_release(self, basename="background_file"):
        assert(self.is_mounted())

        path = os.path.join(self.hostfs_mntpt, basename)

        script = """
            import time
            import fcntl
            import struct
            f1 = open("{path}-1", 'w')
            fcntl.flock(f1, fcntl.LOCK_EX)
            f2 = open("{path}-2", 'w')
            lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
            fcntl.fcntl(f2, fcntl.F_SETLK, lockdata)
            """
        pyscript = dedent(script).format(path=path)

        log.info("lock_and_release file {0}".format(basename))
        return self._run_python(pyscript)

    def check_filelock(self, basename="background_file", do_flock=True):
        assert(self.is_mounted())

        path = os.path.join(self.hostfs_mntpt, basename)

        script_builder = """
            import fcntl
            import errno
            import struct"""
        if do_flock:
            script_builder += """
            f1 = open("{path}-1", 'r')
            try:
                fcntl.flock(f1, fcntl.LOCK_EX | fcntl.LOCK_NB)
            except IOError as e:
                if e.errno == errno.EAGAIN:
                    pass
            else:
                raise RuntimeError("flock on file {path}-1 not found")"""
        script_builder += """
            f2 = open("{path}-2", 'r')
            try:
                lockdata = struct.pack('hhllhh', fcntl.F_WRLCK, 0, 0, 0, 0, 0)
                fcntl.fcntl(f2, fcntl.F_SETLK, lockdata)
            except IOError as e:
                if e.errno == errno.EAGAIN:
                    pass
            else:
                raise RuntimeError("posix lock on file {path}-2 not found")
            """
        pyscript = dedent(script_builder).format(path=path)

        log.info("check lock on file {0}".format(basename))
        self.client_remote.run(args=[
            'python3', '-c', pyscript
        ])

    def write_background(self, basename="background_file", loop=False):
        """
        Open a file for writing, complete as soon as you can
        :param basename:
        :return:
        """
        assert(self.is_mounted())

        path = os.path.join(self.hostfs_mntpt, basename)

        pyscript = dedent("""
            import os
            import time

            fd = os.open("{path}", os.O_RDWR | os.O_CREAT, 0o644)
            try:
                while True:
                    os.write(fd, b'content')
                    time.sleep(1)
                    if not {loop}:
                        break
            except IOError as e:
                pass
            os.close(fd)
            """).format(path=path, loop=str(loop))

        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)
        return rproc

    def write_n_mb(self, filename, n_mb, seek=0, wait=True):
        """
        Write the requested number of megabytes to a file
        """
        assert(self.is_mounted())

        return self.run_shell(["dd", "if=/dev/urandom", "of={0}".format(filename),
                               "bs=1M", "conv=fdatasync",
                               "count={0}".format(int(n_mb)),
                               "seek={0}".format(int(seek))
                               ], wait=wait)

    def write_test_pattern(self, filename, size):
        log.info("Writing {0} bytes to {1}".format(size, filename))
        return self.run_python(dedent("""
            import zlib
            path = "{path}"
            with open(path, 'w') as f:
                for i in range(0, {size}):
                    val = zlib.crc32(str(i).encode('utf-8')) & 7
                    f.write(chr(val))
        """.format(
            path=os.path.join(self.hostfs_mntpt, filename),
            size=size
        )))

    def validate_test_pattern(self, filename, size):
        log.info("Validating {0} bytes from {1}".format(size, filename))
        return self.run_python(dedent("""
            import zlib
            path = "{path}"
            with open(path, 'r') as f:
                bytes = f.read()
            if len(bytes) != {size}:
                raise RuntimeError("Bad length {{0}} vs. expected {{1}}".format(
                    len(bytes), {size}
                ))
            for i, b in enumerate(bytes):
                val = zlib.crc32(str(i).encode('utf-8')) & 7
                if b != chr(val):
                    raise RuntimeError("Bad data at offset {{0}}".format(i))
        """.format(
            path=os.path.join(self.hostfs_mntpt, filename),
            size=size
        )))

    def open_n_background(self, fs_path, count):
        """
        Open N files for writing, hold them open in a background process

        :param fs_path: Path relative to CephFS root, e.g. "foo/bar"
        :return: a RemoteProcess
        """
        assert(self.is_mounted())

        abs_path = os.path.join(self.hostfs_mntpt, fs_path)

        pyscript = dedent("""
            import sys
            import time
            import os

            n = {count}
            abs_path = "{abs_path}"

            if not os.path.exists(abs_path):
                os.makedirs(abs_path)

            handles = []
            for i in range(0, n):
                fname = "file_"+str(i)
                path = os.path.join(abs_path, fname)
                handles.append(open(path, 'w'))

            while True:
                time.sleep(1)
            """).format(abs_path=abs_path, count=count)

        rproc = self._run_python(pyscript)
        self.background_procs.append(rproc)
        return rproc

    def create_n_files(self, fs_path, count, sync=False):
        assert(self.is_mounted())

        abs_path = os.path.join(self.hostfs_mntpt, fs_path)

        pyscript = dedent("""
            import sys
            import time
            import os

            n = {count}
            abs_path = "{abs_path}"

            if not os.path.exists(os.path.dirname(abs_path)):
                os.makedirs(os.path.dirname(abs_path))

            for i in range(0, n):
                fname = "{{0}}_{{1}}".format(abs_path, i)
                with open(fname, 'w') as f:
                    f.write('content')
                    if {sync}:
                        f.flush()
                        os.fsync(f.fileno())
            """).format(abs_path=abs_path, count=count, sync=str(sync))

        self.run_python(pyscript)

    def teardown(self):
        for p in self.background_procs:
            log.info("Terminating background process")
            self._kill_background(p)

        self.background_procs = []

    def _kill_background(self, p):
        if p.stdin:
            p.stdin.close()
            try:
                p.wait()
            except (CommandFailedError, ConnectionLostError):
                pass

    def kill_background(self, p):
        """
        For a process that was returned by one of the _background member functions,
        kill it hard.
        """
        self._kill_background(p)
        self.background_procs.remove(p)

    def send_signal(self, signal):
        signal = signal.lower()
        if signal.lower() not in ['sigstop', 'sigcont', 'sigterm', 'sigkill']:
            raise NotImplementedError

        self.client_remote.run(args=['sudo', 'kill', '-{0}'.format(signal),
                                self.client_pid], omit_sudo=False)

    def get_global_id(self):
        raise NotImplementedError()

    def get_global_inst(self):
        raise NotImplementedError()

    def get_global_addr(self):
        raise NotImplementedError()

    def get_osd_epoch(self):
        raise NotImplementedError()

    def get_op_read_count(self):
        raise NotImplementedError()

    def lstat(self, fs_path, follow_symlinks=False, wait=True):
        return self.stat(fs_path, follow_symlinks=False, wait=True)

    def stat(self, fs_path, follow_symlinks=True, wait=True):
        """
        stat a file, and return the result as a dictionary like this:
        {
          "st_ctime": 1414161137.0,
          "st_mtime": 1414161137.0,
          "st_nlink": 33,
          "st_gid": 0,
          "st_dev": 16777218,
          "st_size": 1190,
          "st_ino": 2,
          "st_uid": 0,
          "st_mode": 16877,
          "st_atime": 1431520593.0
        }

        Raises exception on absent file.
        """
        abs_path = os.path.join(self.hostfs_mntpt, fs_path)
        if follow_symlinks:
            stat_call = "os.stat('" + abs_path + "')"
        else:
            stat_call = "os.lstat('" + abs_path + "')"

        pyscript = dedent("""
            import os
            import stat
            import json
            import sys

            try:
                s = {stat_call}
            except OSError as e:
                sys.exit(e.errno)

            attrs = ["st_mode", "st_ino", "st_dev", "st_nlink", "st_uid", "st_gid", "st_size", "st_atime", "st_mtime", "st_ctime"]
            print(json.dumps(
                dict([(a, getattr(s, a)) for a in attrs]),
                indent=2))
            """).format(stat_call=stat_call)
        proc = self._run_python(pyscript)
        if wait:
            proc.wait()
            return json.loads(proc.stdout.getvalue().strip())
        else:
            return proc

    def touch(self, fs_path):
        """
        Create a dentry if it doesn't already exist.  This python
        implementation exists because the usual command line tool doesn't
        pass through error codes like EIO.

        :param fs_path:
        :return:
        """
        abs_path = os.path.join(self.hostfs_mntpt, fs_path)
        pyscript = dedent("""
            import sys
            import errno

            try:
                f = open("{path}", "w")
                f.close()
            except IOError as e:
                sys.exit(errno.EIO)
            """).format(path=abs_path)
        proc = self._run_python(pyscript)
        proc.wait()

    def path_to_ino(self, fs_path, follow_symlinks=True):
        abs_path = os.path.join(self.hostfs_mntpt, fs_path)

        if follow_symlinks:
            pyscript = dedent("""
                import os
                import stat

                print(os.stat("{path}").st_ino)
                """).format(path=abs_path)
        else:
            pyscript = dedent("""
                import os
                import stat

                print(os.lstat("{path}").st_ino)
                """).format(path=abs_path)

        proc = self._run_python(pyscript)
        proc.wait()
        return int(proc.stdout.getvalue().strip())

    def path_to_nlink(self, fs_path):
        abs_path = os.path.join(self.hostfs_mntpt, fs_path)

        pyscript = dedent("""
            import os
            import stat

            print(os.stat("{path}").st_nlink)
            """).format(path=abs_path)

        proc = self._run_python(pyscript)
        proc.wait()
        return int(proc.stdout.getvalue().strip())

    def ls(self, path=None):
        """
        Wrap ls: return a list of strings
        """
        cmd = ["ls"]
        if path:
            cmd.append(path)

        ls_text = self.run_shell(cmd).stdout.getvalue().strip()

        if ls_text:
            return ls_text.split("\n")
        else:
            # Special case because otherwise split on empty string
            # gives you [''] instead of []
            return []

    def setfattr(self, path, key, val):
        """
        Wrap setfattr.

        :param path: relative to mount point
        :param key: xattr name
        :param val: xattr value
        :return: None
        """
        self.run_shell(["setfattr", "-n", key, "-v", val, path])

    def getfattr(self, path, attr):
        """
        Wrap getfattr: return the values of a named xattr on one file, or
        None if the attribute is not found.

        :return: a string
        """
        p = self.run_shell(["getfattr", "--only-values", "-n", attr, path], wait=False)
        try:
            p.wait()
        except CommandFailedError as e:
            if e.exitstatus == 1 and "No such attribute" in p.stderr.getvalue():
                return None
            else:
                raise

        return str(p.stdout.getvalue())

    def df(self):
        """
        Wrap df: return a dict of usage fields in bytes
        """

        p = self.run_shell(["df", "-B1", "."])
        lines = p.stdout.getvalue().strip().split("\n")
        fs, total, used, avail = lines[1].split()[:4]
        log.warning(lines)

        return {
            "total": int(total),
            "used": int(used),
            "available": int(avail)
        }

    def dir_checksum(self, path=None, follow_symlinks=False):
        cmd = ["find"]
        if follow_symlinks:
            cmd.append("-L")
        if path:
            cmd.append(path)
        cmd.extend(["-type", "f", "-exec", "md5sum", "{}", "+"])
        checksum_text = self.run_shell(cmd).stdout.getvalue().strip()
        checksum_sorted = sorted(checksum_text.split('\n'), key=lambda v: v.split()[1])
        return hashlib.md5(('\n'.join(checksum_sorted)).encode('utf-8')).hexdigest()