Merge tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull dcache updates from Al Viro:

 - d_alloc_parallel() API change (Neil's with my changes)

 - NORCU fixes

 - Reorganization and simplification of dentry eviction logic

 - Simplifying rcu_read_lock() scopes in fs/dcache.c

 - Secondary roots work - getting rid of NFS fake root dentries and
   dealing with remaining shrink_dcache_for_umount() and
   shrink_dentry_list() races

 - making cursors NORCU (surprisingly easy)

* tag 'pull-dcache' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (22 commits)
  make cursors NORCU
  nfs: get rid of fake root dentries
  wind ->s_roots via ->d_sib instead of ->d_hash
  shrink_dentry_tree(): unify the calls of shrink_dentry_list()
  shrinking rcu_read_lock() scope in d_alloc_parallel()
  d_walk(): shrink rcu_read_lock() scope
  document dentry_kill()
  adjust calling conventions of lock_for_kill(), fold __dentry_kill() into dentry_kill()
  Document rcu_read_lock() use in select_collect2()
  Shift rcu_read_{,un}lock() inside fast_dput()
  simplify safety for lock_for_kill() slowpath
  fold lock_for_kill() and __dentry_kill() into common helper
  fold lock_for_kill() into shrink_kill()
  shrink_dentry_list(): start with removing from shrink list
  d_prune_aliases(): make sure to skip NORCU aliases
  kill d_dispose_if_unused()
  make to_shrink_list() return whether it has moved dentry to list
  select_collect(): ignore dentries on shrink lists if they have positive refcounts
  find_acceptable_alias(): skip NORCU aliases with zero refcount
  fix a race between d_find_any_alias() and final dput() of NORCU dentries
  ...

1 files changed, 17 insertions, 0 deletions

diff --git a/Documentation/filesystems/porting.rst b/Documentation/filesystems/porting.rst
index f546b1d3897f..d13f0a23c882 100644
--- a/Documentation/filesystems/porting.rst
+++ b/Documentation/filesystems/porting.rst
@@ -1384,3 +1384,20 @@ for_each_alias(dentry, inode) instead of hlist_for_each_entry; better
 yet, see if any of the exported primitives could be used instead of
 the entire loop.  You still need to hold ->i_lock of the inode over
 either form of manual loop.
+
+---
+
+**mandatory**
+
+d_alloc_parallel() no longer requires a waitqueue_head.
+
+---
+
+**mandatory**
+
+d_dispose_if_unused() is gone; use __move_to_shrink_list() if you really
+need that functionality, but watch out for memory safety issues - just
+as with d_dispose_if_unused() these are not trivial; with this variant
+of API it's more explicit, since grabbing ->d_lock is caller-side, but
+d_dispose_if_unused() had all the same issues.  It's a low-level primitive;
+use only if you have no alternative.