fs: change d_compare for rcu-walk

Change d_compare so it may be called from lock-free RCU lookups. This
does put significant restrictions on what may be done from the callback,
however there don't seem to have been any problems with in-tree fses.
If some strange use case pops up that _really_ cannot cope with the
rcu-walk rules, we can just add new rcu-unaware callbacks, which would
cause name lookup to drop out of rcu-walk mode.

For in-tree filesystems, this is just a mechanical change.

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

1 files changed, 3 insertions, 1 deletions

diff --git a/fs/dcache.c b/fs/dcache.c
index 814e5f491e9c..7075555fbb04 100644
--- a/fs/dcache.c
+++ b/fs/dcache.c
@@ -1437,7 +1437,9 @@ struct dentry * __d_lookup(struct dentry * parent, struct qstr * name)
                  */
                 qstr = &dentry->d_name;
                 if (parent->d_op && parent->d_op->d_compare) {
-                        if (parent->d_op->d_compare(parent, qstr, name))
+                        if (parent->d_op->d_compare(parent, parent->d_inode,
+                                                dentry, dentry->d_inode,
+                                                qstr->len, qstr->name, name))
                                 goto next;
                 } else {
                         if (qstr->len != len)