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/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 33fa3e5d38fd..9a76f8d8bf95 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -11,7 +11,9 @@ be able to use diff(1).
 prototypes:
         int (*d_revalidate)(struct dentry *, int);
         int (*d_hash) (struct dentry *, struct qstr *);
-        int (*d_compare) (struct dentry *, struct qstr *, struct qstr *);
+        int (*d_compare)(const struct dentry *, const struct inode *,
+                        const struct dentry *, const struct inode *,
+                        unsigned int, const char *, const struct qstr *);
         int (*d_delete)(struct dentry *);
         void (*d_release)(struct dentry *);
         void (*d_iput)(struct dentry *, struct inode *);