linux.git/fs/nfsd, branch v4.8

nfsd: don't return an unhashed lock stateid after taking mutex

2016-08-12T20:10:25+00:00

nfsd4_lock will take the st_mutex before working with the stateid it
gets, but between the time when we drop the cl_lock and take the mutex,
the stateid could become unhashed (a'la FREE_STATEID). If that happens
the lock stateid returned to the client will be forgotten.

Fix this by first moving the st_mutex acquisition into
lookup_or_create_lock_state. Then, have it check to see if the lock
stateid is still hashed after taking the mutex. If it's not, then put
the stateid and try the find/create again.

Signed-off-by: Jeff Layton 
Tested-by: Alexey Kodanev 
Cc: stable@vger.kernel.org # feb9dad5 nfsd: Always lock state exclusively.
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields

nfsd: Fix race between FREE_STATEID and LOCK

2016-08-11T19:08:39+00:00

When running LTP's nfslock01 test, the Linux client can send a LOCK
and a FREE_STATEID request at the same time. The outcome is:

Frame 324    R OPEN stateid [2,O]

Frame 115004 C LOCK lockowner_is_new stateid [2,O] offset 672000 len 64
Frame 115008 R LOCK stateid [1,L]
Frame 115012 C WRITE stateid [0,L] offset 672000 len 64
Frame 115016 R WRITE NFS4_OK
Frame 115019 C LOCKU stateid [1,L] offset 672000 len 64
Frame 115022 R LOCKU NFS4_OK
Frame 115025 C FREE_STATEID stateid [2,L]
Frame 115026 C LOCK lockowner_is_new stateid [2,O] offset 672128 len 64
Frame 115029 R FREE_STATEID NFS4_OK
Frame 115030 R LOCK stateid [3,L]
Frame 115034 C WRITE stateid [0,L] offset 672128 len 64
Frame 115038 R WRITE NFS4ERR_BAD_STATEID

In other words, the server returns stateid L in a successful LOCK
reply, but it has already released it. Subsequent uses of stateid L
fail.

To address this, protect the generation check in nfsd4_free_stateid
with the st_mutex. This should guarantee that only one of two
outcomes occurs: either LOCK returns a fresh valid stateid, or
FREE_STATEID returns NFS4ERR_LOCKS_HELD.

Reported-by: Alexey Kodanev 
Fix-suggested-by: Jeff Layton 
Signed-off-by: Chuck Lever 
Tested-by: Alexey Kodanev 
Cc: stable@vger.kernel.org
Signed-off-by: J. Bruce Fields

nfsd: fix dentry refcounting on create

2016-08-11T15:42:08+00:00

b44061d0b9 introduced a dentry ref counting bug.  Previously we were
grabbing one ref to dchild in nfsd_create(), but with the creation of
nfsd_create_locked() we have a ref for dchild from the lookup in
nfsd_create(), and then another ref in nfsd_create_locked().  The ref
from the lookup in nfsd_create() is never dropped and results in
dentries still in use at unmount.

Signed-off-by: Josef Bacik 
Fixes: b44061d0b9 "nfsd: reorganize nfsd_create"
Reported-by: kernel test robot 
Reviewed-by: Jeff Layton 
Acked-by: Al Viro 
Signed-off-by: J. Bruce Fields

Merge tag 'nfsd-4.8' of git://linux-nfs.org/~bfields/linux

2016-08-04T23:59:06+00:00

Pull nfsd updates from Bruce Fields:
 "Highlights:

   - Trond made a change to the server's tcp logic that allows a fast
     client to better take advantage of high bandwidth networks, but may
     increase the risk that a single client could starve other clients;
     a new sunrpc.svc_rpc_per_connection_limit parameter should help
     mitigate this in the (hopefully unlikely) event this becomes a
     problem in practice.

   - Tom Haynes added a minimal flex-layout pnfs server, which is of no
     use in production for now--don't build it unless you're doing
     client testing or further server development"

* tag 'nfsd-4.8' of git://linux-nfs.org/~bfields/linux: (32 commits)
  nfsd: remove some dead code in nfsd_create_locked()
  nfsd: drop unnecessary MAY_EXEC check from create
  nfsd: clean up bad-type check in nfsd_create_locked
  nfsd: remove unnecessary positive-dentry check
  nfsd: reorganize nfsd_create
  nfsd: check d_can_lookup in fh_verify of directories
  nfsd: remove redundant zero-length check from create
  nfsd: Make creates return EEXIST instead of EACCES
  SUNRPC: Detect immediate closure of accepted sockets
  SUNRPC: accept() may return sockets that are still in SYN_RECV
  nfsd: allow nfsd to advertise multiple layout types
  nfsd: Close race between nfsd4_release_lockowner and nfsd4_lock
  nfsd/blocklayout: Make sure calculate signature/designator length aligned
  xfs: abstract block export operations from nfsd layouts
  SUNRPC: Remove unused callback xpo_adjust_wspace()
  SUNRPC: Change TCP socket space reservation
  SUNRPC: Add a server side per-connection limit
  SUNRPC: Micro optimisation for svc_data_ready
  SUNRPC: Call the default socket callbacks instead of open coding
  SUNRPC: lock the socket while detaching it
  ...

nfsd: remove some dead code in nfsd_create_locked()

2016-08-04T21:11:53+00:00

We changed this around in f135af1041f ('nfsd: reorganize nfsd_create')
so "dchild" can't be an error pointer any more.  Also, dchild can't be
NULL here (and dput would already handle this even if it was).

Signed-off-by: Dan Carpenter 
Signed-off-by: J. Bruce Fields

nfsd: drop unnecessary MAY_EXEC check from create

2016-08-04T21:11:52+00:00

We need an fh_verify to make sure we at least have a dentry, but actual
permission checks happen later.

Signed-off-by: J. Bruce Fields

nfsd: clean up bad-type check in nfsd_create_locked

2016-08-04T21:11:51+00:00

Minor cleanup, no change in behavior.

Signed-off-by: J. Bruce Fields

nfsd: remove unnecessary positive-dentry check

2016-08-04T21:11:50+00:00

vfs_{create,mkdir,mknod} each begin with a call to may_create(), which
returns EEXIST if the object already exists.

This check is therefore unnecessary.

(In the NFSv2 case, nfsd_proc_create also has such a check.  Contrary to
RFC 1094, our code seems to believe that a CREATE of an existing file
should succeed.  I'm leaving that behavior alone.)

Signed-off-by: J. Bruce Fields

nfsd: reorganize nfsd_create

2016-08-04T21:11:49+00:00

There's some odd logic in nfsd_create() that allows it to be called with
the parent directory either locked or unlocked.  The only already-locked
caller is NFSv2's nfsd_proc_create().  It's less confusing to split out
the unlocked case into a separate function which the NFSv2 code can call
directly.

Also fix some comments while we're here.

Signed-off-by: J. Bruce Fields

nfsd: check d_can_lookup in fh_verify of directories

2016-08-04T21:11:48+00:00

Create and other nfsd ops generally assume we can call lookup_one_len on
inodes with S_IFDIR set.  Al says that this assumption isn't true in
general, though it should be for the filesystem objects nfsd sees.

Add a check just to make sure our assumption isn't violated.

Remove a couple checks for i_op->lookup in create code.

Cc: Al Viro 
Signed-off-by: J. Bruce Fields