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Support NFSv4 only environment
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NFSv4 only environments don't support `rpcinfo`
and `showmount` calls as they're missing NFSv3
services.

When `rpcinfo` or `showmount` fails, try to mount
NFSv4 pseudo FS '/' to add '4' to supported NFS versions
and run `ls` on the mounted pseudo FS to offer the first
folder level of exports.

See: xapi-project#551
And: xcp-ng/xcp#135

Signed-off-by: BenjiReis <[email protected]>
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@benjamreis
benjamreis committed Jul 19, 2023
1 parent 877403d commit f6e3a3f
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Showing 4 changed files with 121 additions and 88 deletions.
10 changes: 6 additions & 4 deletions drivers/NFSSR.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -113,11 +113,13 @@ def validate_remotepath(self, scan):
def check_server(self):
try:
if PROBEVERSION in self.dconf:
sv = nfs.get_supported_nfs_versions(self.remoteserver)
sv = nfs.get_supported_nfs_versions(self.remoteserver, self.transport)
if len(sv):
self.nfsversion = sv[0]
else:
nfs.check_server_tcp(self.remoteserver, self.nfsversion)
if not nfs.check_server_tcp(self.remoteserver, self.transport, self.nfsversion):
raise nfs.NfsException("Unsupported NFS version: %s" % self.nfsversion)

except nfs.NfsException as exc:
raise xs_errors.XenError('NFSVersion',
opterr=exc.errstr)
Expand Down Expand Up @@ -163,7 +165,7 @@ def probe(self):

self.mount(temppath, self.remotepath)
try:
return nfs.scan_srlist(temppath, self.dconf)
return nfs.scan_srlist(temppath, self.transport, self.dconf)
finally:
try:
nfs.unmount(temppath, True)
Expand Down Expand Up @@ -250,7 +252,7 @@ def vdi(self, uuid, loadLocked=False):

def scan_exports(self, target):
util.SMlog("scanning2 (target=%s)" % target)
dom = nfs.scan_exports(target)
dom = nfs.scan_exports(target, self.transport)
print(dom.toprettyxml(), file=sys.stderr)

def set_transport(self):
Expand Down
148 changes: 93 additions & 55 deletions drivers/nfs.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@

RPCINFO_BIN = "/usr/sbin/rpcinfo"
SHOWMOUNT_BIN = "/usr/sbin/showmount"
NFS_STAT = "/usr/sbin/nfsstat"

DEFAULT_NFSVERSION = '3'

Expand All @@ -50,34 +51,41 @@
NFS_SERVICE_WAIT = 30
NFS_SERVICE_RETRY = 6

NSFv4_PSEUDOFS = "/"
NFS4_TMP_MOUNTPOINT = "/tmp/mnt"

class NfsException(Exception):

def __init__(self, errstr):
self.errstr = errstr


def check_server_tcp(server, nfsversion=DEFAULT_NFSVERSION):
def check_server_tcp(server, transport, nfsversion=[DEFAULT_NFSVERSION]):
"""Make sure that NFS over TCP/IP V3 is supported on the server.
Returns True if everything is OK
False otherwise.
"""

try:
sv = get_supported_nfs_versions(server)
return (True if nfsversion in sv else False)
sv = get_supported_nfs_versions(server, transport)
return (nfsversion[0] in sv)
except util.CommandException as inst:
raise NfsException("rpcinfo failed or timed out: return code %d" %
inst.code)


def check_server_service(server):
def check_server_service(server, transport):
"""Ensure NFS service is up and available on the remote server.
Returns False if fails to detect service after
NFS_SERVICE_RETRY * NFS_SERVICE_WAIT
"""

sv = get_supported_nfs_versions(server, transport)
# Services are not present in NFS4 only, this doesn't mean there's no NFS
if sv == ['4']:
return True

retries = 0
errlist = [errno.EPERM, errno.EPIPE, errno.EIO]

Expand Down Expand Up @@ -129,18 +137,6 @@ def soft_mount(mountpoint, remoteserver, remotepath, transport, useroptions='',
raise NfsException("Failed to make directory: code is %d" %
inst.code)


# Wait for NFS service to be available
try:
if not check_server_service(remoteserver):
raise util.CommandException(
code=errno.EOPNOTSUPP,
reason='No NFS service on server: `%s`' % remoteserver
)
except util.CommandException as inst:
raise NfsException("Failed to detect NFS service on server `%s`"
% remoteserver)

mountcommand = 'mount.nfs'

options = "soft,proto=%s,vers=%s" % (
Expand Down Expand Up @@ -186,43 +182,75 @@ def unmount(mountpoint, rmmountpoint):
raise NfsException("rmdir failed with error '%s'" % inst.strerror)


def scan_exports(target):
def scan_exports(target, transport):
"""Scan target and return an XML DOM with target, path and accesslist."""
util.SMlog("scanning")
cmd = [SHOWMOUNT_BIN, "--no-headers", "-e", target]
dom = xml.dom.minidom.Document()
element = dom.createElement("nfs-exports")
dom.appendChild(element)
for val in util.pread2(cmd).split('\n'):
if not len(val):
continue
entry = dom.createElement('Export')
element.appendChild(entry)

subentry = dom.createElement("Target")
entry.appendChild(subentry)
textnode = dom.createTextNode(target)
subentry.appendChild(textnode)

# Access is not always provided by showmount return
# If none is provided we need to assume "*"
array = val.split()
path = array[0]
access = array[1] if len(array) >= 2 else "*"
subentry = dom.createElement("Path")
entry.appendChild(subentry)
textnode = dom.createTextNode(path)
subentry.appendChild(textnode)

subentry = dom.createElement("Accesslist")
entry.appendChild(subentry)
textnode = dom.createTextNode(access)
subentry.appendChild(textnode)

return dom


def scan_srlist(path, dconf):
try:
cmd = [SHOWMOUNT_BIN, "--no-headers", "-e", target]
for val in util.pread2(cmd).split('\n'):
if not len(val):
continue
entry = dom.createElement('Export')
element.appendChild(entry)

subentry = dom.createElement("Target")
entry.appendChild(subentry)
textnode = dom.createTextNode(target)
subentry.appendChild(textnode)

# Access is not always provided by showmount return
# If none is provided we need to assume "*"
array = val.split()
path = array[0]
access = array[1] if len(array) >= 2 else "*"
subentry = dom.createElement("Path")
entry.appendChild(subentry)
textnode = dom.createTextNode(path)
subentry.appendChild(textnode)

subentry = dom.createElement("Accesslist")
entry.appendChild(subentry)
textnode = dom.createTextNode(access)
subentry.appendChild(textnode)
return dom
except Exception:
util.SMlog("Unable to scan exports with %s, trying NFSv4" % SHOWMOUNT_BIN)

# NFSv4 only
try:
mountpoint = "%s/%s" % (NFS4_TMP_MOUNTPOINT, target)
soft_mount(mountpoint, target, NSFv4_PSEUDOFS, transport, nfsversion='4')
paths = os.listdir(mountpoint)
unmount(mountpoint, NSFv4_PSEUDOFS)
for path in paths:
entry = dom.createElement('Export')
element.appendChild(entry)

subentry = dom.createElement("Target")
entry.appendChild(subentry)
textnode = dom.createTextNode(target)
subentry.appendChild(textnode)
subentry = dom.createElement("Path")
entry.appendChild(subentry)
textnode = dom.createTextNode(path)
subentry.appendChild(textnode)

subentry = dom.createElement("Accesslist")
entry.appendChild(subentry)
# Assume everyone as we do not have any info about it
textnode = dom.createTextNode("*")
subentry.appendChild(textnode)
return dom
except Exception:
util.SMlog("Unable to scan exports with NFSv4 pseudo FS mount")

raise NfsException('Failed to read NFS export paths from server %s' %
(target))

def scan_srlist(path, transport, dconf):
"""Scan and report SR, UUID."""
dom = xml.dom.minidom.Document()
element = dom.createElement("SRlist")
Expand All @@ -245,7 +273,7 @@ def scan_srlist(path, dconf):
if PROBEVERSION in dconf:
util.SMlog("Add supported nfs versions to sr-probe")
try:
supported_versions = get_supported_nfs_versions(dconf.get('server'))
supported_versions = get_supported_nfs_versions(dconf.get('server'), transport)
supp_ver = dom.createElement("SupportedVersions")
element.appendChild(supp_ver)

Expand All @@ -261,7 +289,7 @@ def scan_srlist(path, dconf):
return dom.toprettyxml()


def get_supported_nfs_versions(server):
def get_supported_nfs_versions(server, transport):
"""Return list of supported nfs versions."""
valid_versions = set(['3', '4'])
cv = set()
Expand All @@ -274,11 +302,21 @@ def get_supported_nfs_versions(server):
for j in range(len(cvi)):
cv.add(cvi[j])
return sorted(cv & valid_versions)
except:
util.SMlog("Unable to obtain list of valid nfs versions")
raise NfsException('Failed to read supported NFS version from server %s' %
(server))
except Exception:
util.SMlog("Unable to obtain list of valid nfs versions with %s, trying NSFv4" % RPCINFO_BIN)

# NFSv4 only
try:
mountpoint = "%s/%s" % (NFS4_TMP_MOUNTPOINT, server)
soft_mount(mountpoint, server, NSFv4_PSEUDOFS, transport, nfsversion='4')
util.pread2([NFS_STAT, '-m'])
unmount(mountpoint, NSFv4_PSEUDOFS)
return ['4']
except Exception:
util.SMlog("Unable to obtain list of valid nfs versions with NSFv4 pseudo FS mount")

raise NfsException('Failed to read supported NFS version from server %s' %
(server))

def get_nfs_timeout(other_config):
nfs_timeout = 100
Expand Down
2 changes: 1 addition & 1 deletion tests/test_NFSSR.py
View file
Original file line number Diff line number Diff line change
Expand Up @@ -121,7 +121,7 @@ def test_attach(self, validate_nfsversion, check_server_tcp, _testhost,

nfssr.attach(None)

check_server_tcp.assert_called_once_with('aServer',
check_server_tcp.assert_called_once_with('aServer', 'tcp',
'aNfsversionChanged')
soft_mount.assert_called_once_with('/var/run/sr-mount/UUID',
'aServer',
Expand Down
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