NFSv4 state recovery is not always successful.  Failure is signalled
by setting the nfs_client.cl_cons_state to a negative (errno) value,
then waking waiters.

Currently this can happen only during mount processing.  I'm about to
add an explicit case where state recovery failure during normal
operation should force all NFS requests waiting on that state recovery
to exit.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The gss_mech_list_pseudoflavors() function provides a list of
currently registered GSS pseudoflavors.  This list does not include
any non-GSS flavors that have been registered with the RPC client.
nfs4_find_root_sec() currently adds these extra flavors by hand.

Instead, nfs4_find_root_sec() should be looking at the set of flavors
that have been explicitly registered via rpcauth_register().  And,
other areas of code will soon need the same kind of list that
contains all flavors the kernel currently knows about (see below).

Rather than cloning the open-coded logic in nfs4_find_root_sec() to
those new places, introduce a generic RPC function that generates a
full list of registered auth flavors and pseudoflavors.

A new rpc_authops method is added that lists a flavor's
pseudoflavors, if it has any.  I encountered an interesting module
loader loop when I tried to get the RPC client to invoke
gss_mech_list_pseudoflavors() by name.

This patch is a pre-requisite for server trunking discovery, and a
pre-requisite for fixing up the in-kernel mount client to do better
automatic security flavor selection.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Squelch compiler warnings:

fs/nfs/nfs4proc.c: In function ‘__nfs4_get_acl_uncached’:
fs/nfs/nfs4proc.c:3811:14: warning: comparison between signed and
	unsigned integer expressions [-Wsign-compare]
fs/nfs/nfs4proc.c:3818:15: warning: comparison between signed and
	unsigned integer expressions [-Wsign-compare]

Introduced by commit bf118a34 "NFSv4: include bitmap in nfsv4 get
acl data", Dec 7, 2011.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

As a finishing touch, add appropriate documenting comments and some
debugging printk's.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Clean up: Instead of open-coded flag manipulation, use test_bit() and
clear_bit() just like all other accessors of the state->flag field.
This also eliminates several unnecessary implicit integer type
conversions.

To make it absolutely clear what is going on, a number of comments
are introduced.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The "state->flags & flags" test in nfs41_check_expired_stateid()
allows the state manager to squelch a TEST_STATEID operation when
it is known for sure that a state ID is no longer valid.  If the
lease was purged, for example, the client already knows that state
ID is now defunct.

But open recovery is still needed for that inode.

To force a call to nfs4_open_expired(), change the default return
value for nfs41_check_expired_stateid() to force open recovery, and
the default return value for nfs41_check_locks() to force lock
recovery, if the requested flags are clear.  Fix suggested by Bryan
Schumaker.

Also, the presence of a delegation state ID must not prevent normal
open recovery.  The delegation state ID must be cleared if it was
revoked, but once cleared I don't think it's presence or absence has
any bearing on whether open recovery is still needed.  So the logic
is adjusted to ignore the TEST_STATEID result for the delegation
state ID.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The result of a TEST_STATEID operation can indicate a few different
things:

  o If NFS_OK is returned, then the client can continue using the
    state ID under test, and skip recovery.

  o RFC 5661 says that if the state ID was revoked, then the client
    must perform an explicit FREE_STATEID before trying to re-open.

  o If the server doesn't recognize the state ID at all, then no
    FREE_STATEID is needed, and the client can immediately continue
    with open recovery.

Let's err on the side of caution: if the server clearly tells us the
state ID is unknown, we skip the FREE_STATEID.  For any other error,
we issue a FREE_STATEID.  Sometimes that FREE_STATEID will be
unnecessary, but leaving unused state IDs on the server needlessly
ties up resources.
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

The TEST_STATEID and FREE_STATEID operations can return
-NFS4ERR_BAD_STATEID, -NFS4ERR_OLD_STATEID, or -NFS4ERR_DEADSESSION.

nfs41_{test,free}_stateid() should not pass these errors to
nfs4_handle_exception() during state recovery, since that will
recursively kick off state recovery again, resulting in a deadlock.

In particular, when the TEST_STATEID operation returns NFS4_OK,
res.status can contain one of these errors.  _nfs41_test_stateid()
replaces NFS4_OK with the value in res.status, which is then returned
to callers.

But res.status is not passed through nfs4_stat_to_errno(), and thus is
a positive NFS4ERR value.  Currently callers are only interested in
!NFS4_OK, and nfs4_handle_exception() ignores positive values.

Thus the res.status values are currently ignored by
nfs4_handle_exception() and won't cause the deadlock above.  Thanks to
this missing negative, it is only when these operations fail (which
is very rare) that a deadlock can occur.

Bryan agrees the original intent was to return res.status as a
negative NFS4ERR value to callers of nfs41_test_stateid().
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

mark_matching_lsegs_invalid() resets the mds_threshold counters and can
dereference the layout hdr on an initial empty plh_segs list. It returns 0 both
in the case of an initial empty list and in a non-emtpy list that was cleared
by calls to mark_lseg_invalid.

Don't send a LAYOUTRETURN if the list was initially empty.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

When the file layout driver is fencing a DS, _pnfs_return_layout can be
called mulitple times per inode due to in-flight i/o referencing lsegs on it's
plh_segs list.

Remember that LAYOUTRETURN has been called, and do not call it again.
Allow LAYOUTRETURNs after a subsequent LAYOUTGET.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

First mark the deviceid invalid to prevent any future use. Then fence all
files involved in I/O to a DS with a connection error by sending a
LAYOUTRETURN.
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

Resolve conflicts with the VFS atomic open and sget changes.

Conflicts:
	fs/nfs/nfs4proc.c

Pass mount flags to sget() so that it can use them in initialising a new
superblock before the set function is called.  They could also be passed to the
compare function.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Add comments describing what the directions "up" and "down" mean and ref count
handling to the VFS mount following family of functions.

Signed-off-by: Valerie Aurora <vaurora@redhat.com> (Original author)
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

copy_tree() can theoretically fail in a case other than ENOMEM, but always
returns NULL which is interpreted by callers as -ENOMEM.  Change it to return
an explicit error.

Also change clone_mnt() for consistency and because union mounts will add new
error cases.

Thanks to Andreas Gruenbacher <agruen@suse.de> for a bug fix.
[AV: folded braino fix by Dan Carpenter]

Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Cc: Valerie Aurora <valerie.aurora@gmail.com>
Cc: Andreas Gruenbacher <agruen@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Make the chown() and lchown() syscalls jump to the fchownat() syscall with the
appropriate extra arguments.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

we want to take it out of mark_files_ro() reach *before* we start
checking if we ought to drop write access.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

mnt_drop_write_file() is safe under any lock
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Cc: Djalal Harouni <tixxdz@opendz.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Add a helper that abstracts out the jump to an already parsed struct path
from ->follow_link operation from procfs.  Not only does this clean up
the code by moving the two sides of this game into a single helper, but
it also prepares for making struct nameidata private to namei.c
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Currently the non-nd_set_link based versions of ->follow_link are expected
to do a path_put(&nd->path) on failure.  This calling convention is unexpected,
undocumented and doesn't match what the nd_set_link-based instances do.

Move the path_put out of the only non-nd_set_link based ->follow_link
instance into the caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

It, debugfs_create_dir() and debugfs_create_link() use the common helper
now.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

same as for nfs et.al.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

a) ->d_iput() is wrong here - what we do to inode is completely usual, it's
dentry->d_fsdata that we want to drop.  Just use ->d_release().

b) switch to ->s_d_op - no need to play with d_set_d_op()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

all callers want the same thing, actually - a kinda-sorta analog of
kern_path_create().  I.e. they want parent vfsmount/dentry (with
->i_mutex held, to make sure the child dentry is still their child)
+ the child dentry.

Signed-off-by Al Viro <viro@zeniv.linux.org.uk>

Since commit 197e37d9, the banner comment on lookup_open() no longer matches
what the function returns.  It used to return a struct file pointer or NULL and
now it returns an integer and is passed the struct file pointer it is to use
amongst its arguments.  Update the comment to reflect this.

Also add a banner comment to atomic_open().
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

all we want is a boolean flag, same as the method gets now
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

boolean "does it have to be exclusive?" flag is passed instead;
Local filesystem should just ignore it - the object is guaranteed
not to be there yet.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Just the flags; only NFS cares even about that, but there are
legitimate uses for such argument.  And getting rid of that
completely would require splitting ->lookup() into a couple
of methods (at least), so let's leave that alone for now...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

just the flags...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

since the method wrapped by it doesn't need that anymore...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Just the lookup flags.  Die, bastard, die...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

just pass the flags
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>