fs: dentry allocation consolidation

fs: dentry allocation consolidation

There are 2 duplicate copies of code in dentry allocation in path lookup.
Consolidate them into a single function.

Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/fs/namei.c b/fs/namei.c
index c2742b7dec595207aed06e78fec1bffed8c9db70..b815a4d2e1d6a326d1aefdcfb4ab5e919dd0de19 100644 (file)
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -685,6 +685,35 @@ static __always_inline void follow_dotdot(struct nameidata *nd)
        follow_mount(&nd->path);
 }
 
+/*
+ * Allocate a dentry with name and parent, and perform a parent
+ * directory ->lookup on it. Returns the new dentry, or ERR_PTR
+ * on error. parent->d_inode->i_mutex must be held. d_lookup must
+ * have verified that no child exists while under i_mutex.
+ */
+static struct dentry *d_alloc_and_lookup(struct dentry *parent,
+                               struct qstr *name, struct nameidata *nd)
+{
+       struct inode *inode = parent->d_inode;
+       struct dentry *dentry;
+       struct dentry *old;
+
+       /* Don't create child dentry for a dead directory. */
+       if (unlikely(IS_DEADDIR(inode)))
+               return ERR_PTR(-ENOENT);
+
+       dentry = d_alloc(parent, name);
+       if (unlikely(!dentry))
+               return ERR_PTR(-ENOMEM);
+
+       old = inode->i_op->lookup(inode, dentry, nd);
+       if (unlikely(old)) {
+               dput(dentry);
+               dentry = old;
+       }
+       return dentry;
+}
+
 /*
  *  It's more convoluted than I'd like it to be, but... it's still fairly
  *  small and for now I'd prefer to have fast path as straight as possible.
@@ -738,30 +767,13 @@ need_lookup:
         * so doing d_lookup() (with seqlock), instead of lockfree __d_lookup
         */
        dentry = d_lookup(parent, name);
-       if (!dentry) {
-               struct dentry *new;
-
-               /* Don't create child dentry for a dead directory. */
-               dentry = ERR_PTR(-ENOENT);
-               if (IS_DEADDIR(dir))
-                       goto out_unlock;
-
-               new = d_alloc(parent, name);
-               dentry = ERR_PTR(-ENOMEM);
-               if (new) {
-                       dentry = dir->i_op->lookup(dir, new, nd);
-                       if (dentry)
-                               dput(new);
-                       else
-                               dentry = new;
-               }
-out_unlock:
+       if (likely(!dentry)) {
+               dentry = d_alloc_and_lookup(parent, name, nd);
                mutex_unlock(&dir->i_mutex);
                if (IS_ERR(dentry))
                        goto fail;
                goto done;
        }
-
        /*
         * Uhhuh! Nasty case: the cache was re-populated while
         * we waited on the semaphore. Need to revalidate.
@@ -1135,24 +1147,8 @@ static struct dentry *__lookup_hash(struct qstr *name,
        if (dentry && dentry->d_op && dentry->d_op->d_revalidate)
                dentry = do_revalidate(dentry, nd);
 
-       if (!dentry) {
-               struct dentry *new;
-
-               /* Don't create child dentry for a dead directory. */
-               dentry = ERR_PTR(-ENOENT);
-               if (IS_DEADDIR(inode))
-                       goto out;
-
-               new = d_alloc(base, name);
-               dentry = ERR_PTR(-ENOMEM);
-               if (!new)
-                       goto out;
-               dentry = inode->i_op->lookup(inode, new, nd);
-               if (!dentry)
-                       dentry = new;
-               else
-                       dput(new);
-       }
+       if (!dentry)
+               dentry = d_alloc_and_lookup(base, name, nd);
 out:
        return dentry;
 }