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  1. May 18, 2016
  3. May 09, 2016
    • J. Bruce Fields's avatar
      nfs: don't share mounts between network namespaces · 7e3fcf61
      J. Bruce Fields authored 
      

There's no guarantee that an IP address in a different network namespace
actually represents the same endpoint.

Also, if we allow unprivileged nfs mounts some day then this might allow
an unprivileged user in another network namespace to misdirect somebody
else's nfs mounts.

If sharing between containers is really what's wanted then that could
still be arranged explicitly, for example with bind mounts.

Reported-by: default avatar"Eric W. Biederman" <ebiederm@redhat.com>
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
      7e3fcf61
    • Chuck Lever's avatar
      NFS: Fix an LOCK/OPEN race when unlinking an open file · 11476e9d
      Chuck Lever authored 
      At Connectathon 2016, we found that recent upstream Linux clients
would occasionally send a LOCK operation with a zero stateid. This
appeared to happen in close proximity to another thread returning
a delegation before unlinking the same file while it remained open.

Earlier, the client received a write delegation on this file and
returned the open stateid. Now, as it is getting ready to unlink the
file, it returns the write delegation. But there is still an open
file descriptor on that file, so the client must OPEN the file
again before it returns the delegation.

Since commit 24311f88 ('NFSv4: Recovery of recalled read
delegations is broken'), nfs_open_delegation_recall() clears the
NFS_DELEGATED_STATE flag _before_ it sends the OPEN. This allows a
racing LOCK on the same inode to be put on the wire before the OPEN
operation has returned a valid open stateid.

To eliminate this race, serialize delegation return with the
acquisition of a file lock on the same file. Adopt the same approach
as is used in the unlock path.

This patch also eliminates a similar race seen when sending a LOCK
operation at the same time as returning a delegation on the same file.

Fixes: 24311f88

 ('NFSv4: Recovery of recalled read ... ')
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
[Anna: Add sentence about LOCK / delegation race]
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
      11476e9d
    • Jeff Layton's avatar
      nfs: have flexfiles mirror keep creds for both ro and rw layouts · 3064b686
      Jeff Layton authored 
      

A mirror can be shared between multiple layouts, even with different
iomodes. That makes stats gathering simpler, but it causes a problem
when we get different creds in READ vs. RW layouts.

The current code drops the newer credentials onto the floor when this
occurs. That's problematic when you fetch a READ layout first, and then
a RW. If the READ layout doesn't have the correct creds to do a write,
then writes will fail.

We could just overwrite the READ credentials with the RW ones, but that
would break the ability for the server to fence the layout for reads if
things go awry. We need to be able to revert to the earlier READ creds
if the RW layout is returned afterward.

The simplest fix is to just keep two sets of creds per mirror. One for
READ layouts and one for RW, and then use the appropriate set depending
on the iomode of the layout segment.

Also fix up some RCU nits that sparse found.

Signed-off-by: default avatarJeff Layton <jeff.layton@primarydata.com>
Signed-off-by: default avatarAnna Schumaker <Anna.Schumaker@Netapp.com>
      3064b686