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  1. 07 9月, 2017 35 次提交
  3. 01 9月, 2017 1 次提交
  5. 17 7月, 2017 1 次提交
    • Y
      ceph: fix race in concurrent readdir · 84583cfb
      由 Yan, Zheng 提交于 
      For a large directory, program needs to issue multiple readdir
syscalls to get all dentries. When there are multiple programs
read the directory concurrently. Following sequence of events
can happen.

 - program calls readdir with pos = 2. ceph sends readdir request
   to mds. The reply contains N1 entries. ceph adds these N1 entries
   to readdir cache.
 - program calls readdir with pos = N1+2. The readdir is satisfied
   by the readdir cache, N2 entries are returned. (Other program
   calls readdir in the middle, which fills the cache)
 - program calls readdir with pos = N1+N2+2. ceph sends readdir
   request to mds. The reply contains N3 entries and it reaches
   directory end. ceph adds these N3 entries to the readdir cache
   and marks directory complete.

The second readdir call does not update fi->readdir_cache_idx.
ceph add the last N3 entries to wrong places.

Cc: stable@vger.kernel.org # v4.3+
Signed-off-by: N"Yan, Zheng" <zyan@redhat.com>
Signed-off-by: NIlya Dryomov <idryomov@gmail.com>
      84583cfb
  7. 16 7月, 2017 1 次提交
    • B
      fs/locks: Remove fl_nspid and use fs-specific l_pid for remote locks · 9d5b86ac
      由 Benjamin Coddington 提交于 
      Since commit c69899a1 "NFSv4: Update of VFS byte range lock must be
atomic with the stateid update", NFSv4 has been inserting locks in rpciod
worker context.  The result is that the file_lock's fl_nspid is the
kworker's pid instead of the original userspace pid.

The fl_nspid is only used to represent the namespaced virtual pid number
when displaying locks or returning from F_GETLK.  There's no reason to set
it for every inserted lock, since we can usually just look it up from
fl_pid.  So, instead of looking up and holding struct pid for every lock,
let's just look up the virtual pid number from fl_pid when it is needed.
That means we can remove fl_nspid entirely.

The translaton and presentation of fl_pid should handle the following four
cases:

1 - F_GETLK on a remote file with a remote lock:
    In this case, the filesystem should determine the l_pid to return here.
    Filesystems should indicate that the fl_pid represents a non-local pid
    value that should not be translated by returning an fl_pid <= 0.

2 - F_GETLK on a local file with a remote lock:
    This should be the l_pid of the lock manager process, and translated.

3 - F_GETLK on a remote file with a local lock, and
4 - F_GETLK on a local file with a local lock:
    These should be the translated l_pid of the local locking process.

Fuse was already doing the correct thing by translating the pid into the
caller's namespace.  With this change we must update fuse to translate
to init's pid namespace, so that the locks API can then translate from
init's pid namespace into the pid namespace of the caller.

With this change, the locks API will expect that if a filesystem returns
a remote pid as opposed to a local pid for F_GETLK, that remote pid will
be <= 0.  This signifies that the pid is remote, and the locks API will
forego translating that pid into the pid namespace of the local calling
process.

Finally, we convert remote filesystems to present remote pids using
negative numbers. Have lustre, 9p, ceph, cifs, and dlm negate the remote
pid returned for F_GETLK lock requests.

Since local pids will never be larger than PID_MAX_LIMIT (which is
currently defined as <= 4 million), but pid_t is an unsigned int, we
should have plenty of room to represent remote pids with negative
numbers if we assume that remote pid numbers are similarly limited.

If this is not the case, then we run the risk of having a remote pid
returned for which there is also a corresponding local pid.  This is a
problem we have now, but this patch should reduce the chances of that
occurring, while also returning those remote pid numbers, for whatever
that may be worth.
Signed-off-by: NBenjamin Coddington <bcodding@redhat.com>
Signed-off-by: NJeff Layton <jlayton@redhat.com>
      9d5b86ac
  9. 07 7月, 2017 2 次提交