new helper: __lookup_slow()

lookup_slow() sans locking/unlocking the directory

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

1 files changed, 18 insertions, 9 deletions

diff --git a/fs/namei.c b/fs/namei.c
index b803c6c6ac95..ba48e154409b 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -1593,22 +1593,21 @@ static int lookup_fast(struct nameidata *nd,
 }
 
 /* Fast lookup failed, do it the slow way */
-static struct dentry *lookup_slow(const struct qstr *name,
-                                  struct dentry *dir,
-                                  unsigned int flags)
+static struct dentry *__lookup_slow(const struct qstr *name,
+                                    struct dentry *dir,
+                                    unsigned int flags)
 {
-        struct dentry *dentry = ERR_PTR(-ENOENT), *old;
+        struct dentry *dentry, *old;
         struct inode *inode = dir->d_inode;
         DECLARE_WAIT_QUEUE_HEAD_ONSTACK(wq);
 
-        inode_lock_shared(inode);
         /* Don't go there if it's already dead */
         if (unlikely(IS_DEADDIR(inode)))
-                goto out;
+                return ERR_PTR(-ENOENT);
 again:
         dentry = d_alloc_parallel(dir, name, &wq);
         if (IS_ERR(dentry))
-                goto out;
+                return dentry;
         if (unlikely(!d_in_lookup(dentry))) {
                 if (!(flags & LOOKUP_NO_REVAL)) {
                         int error = d_revalidate(dentry, flags);
@@ -1630,11 +1629,21 @@ again:
                         dentry = old;
                 }
         }
-out:
-        inode_unlock_shared(inode);
         return dentry;
 }
 
+static struct dentry *lookup_slow(const struct qstr *name,
+                                  struct dentry *dir,
+                                  unsigned int flags)
+{
+        struct inode *inode = dir->d_inode;
+        struct dentry *res;
+        inode_lock_shared(inode);
+        res = __lookup_slow(name, dir, flags);
+        inode_unlock_shared(inode);
+        return res;
+}
+
 static inline int may_lookup(struct nameidata *nd)
 {
         if (nd->flags & LOOKUP_RCU) {