qa/tasks/nvme_loop: set up nvme_loop on scratch_devs

Using an nvme loop device makes the LVs look like "real" disks,
which means we can exercise all of the normal code paths for
provisioning, deprovisioning, and zapping.

Signed-off-by: Sage Weil <sage@newdream.net>

qa/tasks/nvme_loop.py

@@ -0,0 +1,94 @@
+import contextlib
+import logging
+
+from io import StringIO
+from teuthology import misc as teuthology
+from teuthology import contextutil
+from teuthology.orchestra import run
+
+
+log = logging.getLogger(__name__)
+
+
+@contextlib.contextmanager
+def task(ctx, config):
+    log.info('Setting up nvme_loop on scratch devices...')
+    host = 'hostnqn'
+    port = '1'
+    devs_by_remote = {}
+    old_scratch_by_remote = {}
+    for remote, roles in ctx.cluster.remotes.items():
+        devs = teuthology.get_scratch_devices(remote)
+        devs_by_remote[remote] = devs
+        base = '/sys/kernel/config/nvmet'
+        remote.run(
+            args=[
+                'sudo', 'modprobe', 'nvme_loop',
+                run.Raw('&&'),
+                'sudo', 'mkdir', '-p', f'{base}/hosts/{host}',
+                run.Raw('&&'),
+                'sudo', 'mkdir', '-p', f'{base}/ports/{port}',
+                run.Raw('&&'),
+                'echo', 'loop', run.Raw('|'),
+                'sudo', 'tee', f'{base}/ports/{port}/addr_trtype',
+            ]
+        )
+        for dev in devs:
+            short = dev.split('/')[-1]
+            log.info(f'Connecting nvme_loop {remote.shortname}:{dev}...')
+            remote.run(
+                args=[
+                    'sudo', 'mkdir', '-p', f'{base}/subsystems/{short}',
+                    run.Raw('&&'),
+                    'echo', '1', run.Raw('|'),
+                    'sudo', 'tee', f'{base}/subsystems/{short}/attr_allow_any_host',
+                    run.Raw('&&'),
+                    'sudo', 'mkdir', '-p', f'{base}/subsystems/{short}/namespaces/1',
+                    run.Raw('&&'),
+                    'echo', dev, run.Raw('|'),
+                    'sudo', 'tee', f'{base}/subsystems/{short}/namespaces/1/device_path',
+                    run.Raw('&&'),
+                    'echo', '1', run.Raw('|'),
+                    'sudo', 'tee', f'{base}/subsystems/{short}/namespaces/1/enable',
+                    run.Raw('&&'),
+                    'sudo', 'ln', '-s', f'{base}/subsystems/{short}',
+                    f'{base}/ports/{port}/subsystems/{short}',
+                    run.Raw('&&'),
+                    'sudo', 'nvme', 'connect', '-t', 'loop', '-n', short, '-q', host,
+                ]
+            )
+
+        # identify nvme_loops devices
+        old_scratch_by_remote[remote] = remote.read_file('/scratch_devs')
+        p = remote.run(args=['sudo', 'nvme', 'list'], stdout=StringIO())
+        new_devs = []
+        for line in p.stdout.getvalue().splitlines():
+            dev, _, vendor = line.split()[0:3]
+            if dev.startswith('/dev/') and vendor == 'Linux':
+                new_devs.append(dev)
+        log.info(f'new_devs {new_devs}')
+        remote.write_file(
+            path='/scratch_devs',
+            data='\n'.join(new_devs) + '\n',
+            sudo=True
+        )
+
+    try:
+        yield
+
+    finally:
+        for remote, devs in devs_by_remote.items():
+            for dev in devs:
+                short = dev.split('/')[-1]
+                log.info(f'Disconnecting nvme_loop {remote.shortname}:{dev}...')
+                remote.run(
+                    args=[
+                        'sudo', 'nvme', 'disconnect', '-n', short
+                    ],
+                    check_status=False,
+                )
+            remote.write_file(
+                path='/scratch_devs',
+                data=old_scratch_by_remote[remote],
+                sudo=True
+            )