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  1. 04 Apr, 2009 24 commits
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  7. 27 Mar, 2009 3 commits
  9. 18 Mar, 2009 11 commits
    • Chuck Lever's avatar
      SUNRPC: Clean up static inline functions in svc_xprt.h · 2795e53b
      Chuck Lever authored 
      Clean up:  Enable the use of const arguments in higher level svc_ APIs
by adding const to the arguments of the helper functions in svc_xprt.h
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      2795e53b
    • Sachin S. Prabhu's avatar
      Inconsistent setattr behaviour · 0953e620
      Sachin S. Prabhu authored 
      There is an inconsistency seen in the behaviour of nfs compared to other local
filesystems on linux when changing owner or group of a directory. If the
directory has SUID/SGID flags set, on changing owner or group on the directory,
the flags are stripped off on nfs. These flags are maintained on other
filesystems such as ext3.

To reproduce on a nfs share or local filesystem, run the following commands
mkdir test; chmod +s+g test; chown user1 test; ls -ld test

On the nfs share, the flags are stripped and the output seen is
drwxr-xr-x 2 user1 root 4096 Feb 23  2009 test

On other local filesystems(ex: ext3), the flags are not stripped and the output
seen is
drwsr-sr-x 2 user1 root 4096 Feb 23 13:57 test

chown_common() called from sys_chown() will only strip the flags if the inode is
not a directory.
static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
{
..
        if (!S_ISDIR(inode->i_mode))
                newattrs.ia_valid |=
                        ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
..
}

See: http://www.opengroup.org/onlinepubs/7990989775/xsh/chown.html

"If the path argument refers to a regular file, the set-user-ID (S_ISUID) and
set-group-ID (S_ISGID) bits of the file mode are cleared upon successful return
from chown(), unless the call is made by a process with appropriate privileges,
in which case it is implementation-dependent whether these bits are altered. If
chown() is successfully invoked on a file that is not a regular file, these
bits may be cleared. These bits are defined in <sys/stat.h>."

The behaviour as it stands does not appear to violate POSIX.  However the
actions performed are inconsistent when comparing ext3 and nfs.
Signed-off-by: default avatarSachin Prabhu <sprabhu@redhat.com>
Acked-by: default avatarJeff Layton <jlayton@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      0953e620
    • Olga Kornievskaia's avatar
      svcrpc: take advantage of tcp autotuning · 47a14ef1
      Olga Kornievskaia authored 
      Allow the NFSv4 server to make use of TCP autotuning behaviour, which
was previously disabled by setting the sk_userlocks variable.

Set the receive buffers to be big enough to receive the whole RPC
request, and set this for the listening socket, not the accept socket.

Remove the code that readjusts the receive/send buffer sizes for the
accepted socket. Previously this code was used to influence the TCP
window management behaviour, which is no longer needed when autotuning
is enabled.

This can improve IO bandwidth on networks with high bandwidth-delay
products, where a large tcp window is required.  It also simplifies
performance tuning, since getting adequate tcp buffers previously
required increasing the number of nfsd threads.
Signed-off-by: default avatarOlga Kornievskaia <aglo@citi.umich.edu>
Cc: Jim Rees <rees@umich.edu>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      47a14ef1
    • J. Bruce Fields's avatar
      nfsd4: don't check ip address in setclientid · 026722c2
      J. Bruce Fields authored 
      The spec allows clients to change ip address, so we shouldn't be
requiring that setclientid always come from the same address.  For
example, a client could reboot and get a new dhcpd address, but still
present the same clientid to the server.  In that case the server should
revoke the client's previous state and allow it to continue, instead of
(as it currently does) returning a CLID_INUSE error.
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      026722c2
    • Greg Banks's avatar
      knfsd: add file to export stats about nfsd pools · 03cf6c9f
      Greg Banks authored 
      Add /proc/fs/nfsd/pool_stats to export to userspace various
statistics about the operation of rpc server thread pools.

This patch is based on a forward-ported version of
knfsd-add-pool-thread-stats which has been shipping in the SGI
"Enhanced NFS" product since 2006 and which was previously
posted:

http://article.gmane.org/gmane.linux.nfs/10375

It has also been updated thus:

 * moved EXPORT_SYMBOL() to near the function it exports
 * made the new struct struct seq_operations const
 * used SEQ_START_TOKEN instead of ((void *)1)
 * merged fix from SGI PV 990526 "sunrpc: use dprintk instead of
   printk in svc_pool_stats_*()" by Harshula Jayasuriya.
 * merged fix from SGI PV 964001 "Crash reading pool_stats before
   nfsds are started".
Signed-off-by: default avatarGreg Banks <gnb@sgi.com>
Signed-off-by: default avatarHarshula Jayasuriya <harshula@sgi.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      03cf6c9f
    • Greg Banks's avatar
      knfsd: avoid overloading the CPU scheduler with enormous load averages · 59a252ff
      Greg Banks authored 
      Avoid overloading the CPU scheduler with enormous load averages
when handling high call-rate NFS loads.  When the knfsd bottom half
is made aware of an incoming call by the socket layer, it tries to
choose an nfsd thread and wake it up.  As long as there are idle
threads, one will be woken up.

If there are lot of nfsd threads (a sensible configuration when
the server is disk-bound or is running an HSM), there will be many
more nfsd threads than CPUs to run them.  Under a high call-rate
low service-time workload, the result is that almost every nfsd is
runnable, but only a handful are actually able to run.  This situation
causes two significant problems:

1. The CPU scheduler takes over 10% of each CPU, which is robbing
   the nfsd threads of valuable CPU time.

2. At a high enough load, the nfsd threads starve userspace threads
   of CPU time, to the point where daemons like portmap and rpc.mountd
   do not schedule for tens of seconds at a time.  Clients attempting
   to mount an NFS filesystem timeout at the very first step (opening
   a TCP connection to portmap) because portmap cannot wake up from
   select() and call accept() in time.

Disclaimer: these effects were observed on a SLES9 kernel, modern
kernels' schedulers may behave more gracefully.

The solution is simple: keep in each svc_pool a counter of the number
of threads which have been woken but have not yet run, and do not wake
any more if that count reaches an arbitrary small threshold.

Testing was on a 4 CPU 4 NIC Altix using 4 IRIX clients, each with 16
synthetic client threads simulating an rsync (i.e. recursive directory
listing) workload reading from an i386 RH9 install image (161480
regular files in 10841 directories) on the server.  That tree is small
enough to fill in the server's RAM so no disk traffic was involved.
This setup gives a sustained call rate in excess of 60000 calls/sec
before being CPU-bound on the server.  The server was running 128 nfsds.

Profiling showed schedule() taking 6.7% of every CPU, and __wake_up()
taking 5.2%.  This patch drops those contributions to 3.0% and 2.2%.
Load average was over 120 before the patch, and 20.9 after.

This patch is a forward-ported version of knfsd-avoid-nfsd-overload
which has been shipping in the SGI "Enhanced NFS" product since 2006.
It has been posted before:

http://article.gmane.org/gmane.linux.nfs/10374Signed-off-by: default avatarGreg Banks <gnb@sgi.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      59a252ff
    • Greg Banks's avatar
      knfsd: remove the nfsd thread busy histogram · 8bbfa9f3
      Greg Banks authored 
      Stop gathering the data that feeds the 'th' line in /proc/net/rpc/nfsd
because the questionable data provided is not worth the scalability
impact of calculating it.  Instead, always report zeroes.  The current
approach suffers from three major issues:

1. update_thread_usage() increments buckets by call service
   time or call arrival time...in jiffies.  On lightly loaded
   machines, call service times are usually < 1 jiffy; on
   heavily loaded machines call arrival times will be << 1 jiffy.
   So a large portion of the updates to the buckets are rounded
   down to zero, and the histogram is undercounting.

2. As seen previously on the nfs mailing list, the format in which
   the histogram is presented is cryptic, difficult to explain,
   and difficult to use.

3. Updating the histogram requires taking a global spinlock and
   dirtying the global variables nfsd_last_call, nfsd_busy, and
   nfsdstats *twice* on every RPC call, which is a significant
   scaling limitation.

Testing on a 4 CPU 4 NIC Altix using 4 IRIX clients each doing
1K streaming reads at full line rate, shows the stats update code
(inlined into nfsd()) takes about 1.7% of each CPU.  This patch drops
the contribution from nfsd() into the profile noise.

This patch is a forward-ported version of knfsd-remove-nfsd-threadstats
which has been shipping in the SGI "Enhanced NFS" product since 2006.
In that time, exactly one customer has noticed that the threadstats
were missing.  It has been previously posted:

http://article.gmane.org/gmane.linux.nfs/10376

and more recently requested to be posted again.
Signed-off-by: default avatarGreg Banks <gnb@sgi.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      8bbfa9f3
    • J. Bruce Fields's avatar
      nfsd4: remove redundant check from nfsd4_open · 5cb031b0
      J. Bruce Fields authored 
      Note that we already checked for this invalid case at the top of this
function.
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      5cb031b0
    • J. Bruce Fields's avatar
      nfsd4: don't do lookup within readdir in recovery code · 05f4f678
      J. Bruce Fields authored 
      The main nfsd code was recently modified to no longer do lookups from
withing the readdir callback, to avoid locking problems on certain
filesystems.

This (rather hacky, and overdue for replacement) NFSv4 recovery code has
the same problem.  Fix it to build up a list of names (instead of
dentries) and do the lookups afterwards.

Reported symptoms were a deadlock in the xfs code (called from
nfsd4_recdir_load), with /var/lib/nfs on xfs.
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
Reported-by: default avatarDavid Warren <warren@atmos.washington.edu>
      05f4f678
    • J. Bruce Fields's avatar
      nfsd4: support putpubfh operation · a1c8c4d1
      J. Bruce Fields authored 
      Currently putpubfh returns NFSERR_OPNOTSUPP, which isn't actually
allowed for v4.  The right error is probably NFSERR_NOTSUPP.

But let's just implement it; though rarely seen, it can be used by
Solaris (with a special mount option), is mandated by the rfc, and is
trivial for us to support.

Thanks to Yang Hongyang for pointing out the original problem, and to
Mike Eisler, Tom Talpey, Trond Myklebust, and Dave Noveck for further
argument....
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      a1c8c4d1
    • David Shaw's avatar
      Short write in nfsd becomes a full write to the client · 31dec253
      David Shaw authored 
      If a filesystem being written to via NFS returns a short write count
(as opposed to an error) to nfsd, nfsd treats that as a success for
the entire write, rather than the short count that actually succeeded.

For example, given a 8192 byte write, if the underlying filesystem
only writes 4096 bytes, nfsd will ack back to the nfs client that all
8192 bytes were written.  The nfs client does have retry logic for
short writes, but this is never called as the client is told the
complete write succeeded.

There are probably other ways it could happen, but in my case it
happened with a fuse (filesystem in userspace) filesystem which can
rather easily have a partial write.

Here is a patch to properly return the short write count to the
client.
Signed-off-by: default avatarDavid Shaw <dshaw@jabberwocky.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@citi.umich.edu>
      31dec253