vfs: add d_prune dentry operation
This adds a d_prune dentry operation that is called by the VFS prior to
pruning (i.e. unhashing and killing) a hashed dentry from the dcache.
Wrap dentry_lru_del() and use the new _prune() helper in the cases where we
are about to unhash and kill the dentry.
This will be used by Ceph to maintain a flag indicating whether the
complete contents of a directory are contained in the dcache, allowing it
to satisfy lookups and readdir without addition server communication.
Renumber a few DCACHE_* #defines to group DCACHE_OP_PRUNE with the other
DCACHE_OP_ bits.
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 6533807..d819ba1 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -29,6 +29,7 @@
d_compare: yes no no maybe
d_delete: no yes no no
d_release: no no yes no
+d_prune: no yes no no
d_iput: no no yes no
d_dname: no no no no
d_automount: no no yes no