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Subject: Re: [nfsometer PATCH 2/2] trace.py: Add some more error handling to probe_mounts()
From: Weston Andros Adamson <dros@primarydata.com>
In-Reply-To: <1456174931-61514-2-git-send-email-smayhew@redhat.com>
Date: Wed, 2 Mar 2016 13:40:10 -0500
Cc: linux-nfs list <linux-nfs@vger.kernel.org>
Message-Id: <8337C6A7-3B5A-4B11-8F57-F85F4784069D@primarydata.com>
References: <1456174931-61514-1-git-send-email-smayhew@redhat.com> <1456174931-61514-2-git-send-email-smayhew@redhat.com>
To: Scott Mayhew <smayhew@redhat.com>
Sender: linux-nfs-owner@vger.kernel.org

These look good, thanks!

I’ll merge and cut a new release soon.

-dros


> On Feb 22, 2016, at 4:02 PM, Scott Mayhew <smayhew@redhat.com> wrote:
> 
> An nfsometer run can fail very early into the process due to things like
> directory permissions, kerberos creds, and root squashing.  Try to give
> the user some idea why the failure occurred instead of dumping a
> backtrace.
> 
> Signed-off-by: Scott Mayhew <smayhew@redhat.com>
> ---
> nfsometerlib/trace.py | 85 ++++++++++++++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 84 insertions(+), 1 deletion(-)
> 
> diff --git a/nfsometerlib/trace.py b/nfsometerlib/trace.py
> index cd1d3c3..0ab9f85 100644
> --- a/nfsometerlib/trace.py
> +++ b/nfsometerlib/trace.py
> @@ -20,6 +20,7 @@ import multiprocessing
> import signal
> import random
> import atexit
> +import pwd
> 
> from cmd import *
> from config import *
> @@ -517,6 +518,77 @@ def probe_detect(probe_trace_dir, mountopt):
> 
>     return detect
> 
> +def _is_auth_gss():
> +    lines = [ x.strip() for x in file('/proc/self/mountstats') ]
> +    mounted_on = ' mounted on %s with ' % MOUNTDIR
> +    start = -1
> +    end = -1
> +
> +    for i, line in enumerate(lines):
> +        if line.find(mounted_on) >= 0:
> +            assert start == -1
> +            start = i
> +        elif start >= 0 and line.startswith('device '):
> +            assert end == -1
> +            end = i
> +
> +    if end < 0:
> +        end = len(lines)
> +
> +    if start >= 0:
> +        lines = lines[start:end]
> +    else:
> +        return False
> +
> +    for line in lines:
> +        if line.startswith('sec:'):
> +            label, data = line.split(':')
> +            data = data.strip()
> +            if data.startswith('flavor=6'):
> +                return True
> +    return False
> +
> +def _has_creds():
> +    return os.stat(os.path.join(RUNNING_TRACE_DIR,
> +                                'klist_user.start')).st_size != 1
> +
> +def _has_tkt(server):
> +    princ = re.compile('nfs/' + server + '\S+$')
> +    lines = [ x.strip() for x in file(os.path.join(RUNNING_TRACE_DIR,
> +                                                   'klist_user.start')) ]
> +    for i, line in enumerate(lines):
> +        if re.search(princ, line):
> +            return True
> +    return False
> +
> +def _eperm_helper(opts):
> +    server, path = opts.serverpath.split(':')
> +    if _is_auth_gss():
> +        if _has_creds():
> +            if _has_tkt(server):
> +                info = str.format(
> +                    ' Check {:s} on {:s} and ensure user {:s} has the correct'
> +                    ' permission.', path, server,
> +                    pwd.getpwuid(os.getuid())[0])
> +            else:
> +                info = str.format(
> +                    ' No nfs service ticket for {:s} in user {:s}\'s'
> +                    ' credential cache.', server,
> +                    pwd.getpwuid(os.getuid())[0])
> +        else:
> +            info = str.format(
> +                ' User {:s} has no kerberos credentials.',
> +                pwd.getpwuid(os.getuid())[0])
> +    elif os.getuid() == 0:
> +        info = str.format(
> +            ' Check for root squashing in the export options for {:s} on'
> +            ' {:s}.', path, server)
> +    else:
> +       info = str.format(
> +            ' Check {:s} on {:s} and ensure user {:s} has the correct'
> +            ' permission.', path, server, pwd.getpwuid(os.getuid())[0])
> +    return info
> +
> #
> # public api commands
> #
> @@ -746,7 +818,18 @@ def probe_mounts(opts):
>         start(m, opts.serverpath, '__nfsometer-probe', [], [], is_probe=True)
>         fpath = os.path.join(RUNROOT, '__nfsometer-probe')
> 
> -        cmd('mkdir -p "%s"' % RUNROOT)
> +        try:
> +            cmd('mkdir -p "%s"' % RUNROOT)
> +        except CmdErrorCode, e:
> +            msg = str.format('"mkdir -p {:s}" failed.', RUNROOT)
> +            # try to hint why it failed
> +            if e.code == errno.EPERM:
> +                msg += _eperm_helper(opts)
> +            else:
> +                msg += e.errstr
> +            warn(msg)
> +            # and bail out right now
> +            sys.exit(1)
> 
>         f = file(fpath, 'w+')
>         f.write('nfsometer probe to determine server features: %s' % m)
> -- 
> 2.4.3
> 
> --
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