can't blindly check nd->flags in ->d_revalidate()

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

Otherwise you can do things like

# mkdir .snap/foo
# cd .snap/foo/.snap
# ls
<badness>

Signed-off-by: Sage Weil <sage@newdream.net>

First, this was racy anyway: d_release isn't called until well after the
dentry is unhashed.  Second, this runs afoul of the recent dcache change
that clears d_parent prior to calling d_release (949854d0), causing a NULL
pointer dereference.

Signed-off-by: Sage Weil <sage@newdream.net>

Do not set the I_COMPLETE flag on directories until we resolve races with
dcache pruning.

Signed-off-by: Sage Weil <sage@newdream.net>

This reverts commit 97d79b403ef03f729883246208ef5d8a2ebc4d68.

This fails to account for d_parent changes due to rename or disconnected
dentries due to submounts or NFS reexports.

Signed-off-by: Sage Weil <sage@newdream.net>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  ceph: keep reference to parent inode on ceph_dentry
  ceph: queue cap_snaps once per realm
  libceph: fix socket write error handling
  libceph: fix socket read error handling

When creating a new dentry we now hold a reference to the parent
inode in the ceph_dentry.  This is required due to the new RCU
changes from 949854d0, which set dentry->d_parent to NULL in d_kill before
calling the ->release() callback.  If/when that behavior is changed, we can
revert this hack.

Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Sage Weil <sage@newdream.net>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/sage/ceph-client:
  rbd: fix cleanup when trying to mount inexistent image
  net/ceph: make ceph_msgr_wq non-reentrant
  ceph: fsc->*_wq's aren't used in memory reclaim path
  ceph: Always free allocated memory in osdmap_decode()
  ceph: Makefile: Remove unnessary code
  ceph: associate requests with opening sessions
  ceph: drop redundant r_mds field
  ceph: implement DIRLAYOUTHASH feature to get dir layout from MDS
  ceph: add dir_layout to inode

Add a ceph_dir_layout to the inode, and calculate dentry hash values based
on the parent directory's specified dir_hash function.  This is needed
because the old default Linux dcache hash function is extremely week and
leads to a poor distribution of files among dir fragments.

Signed-off-by: Sage Weil <sage@newdream.net>

Require filesystems be aware of .d_revalidate being called in rcu-walk
mode (nd->flags & LOOKUP_RCU). For now do a simple push down, returning
-ECHILD from all implementations.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>