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>

1 files changed, 33 insertions, 37 deletions

diff --git a/fs/namei.c b/fs/namei.c
index c2742b7dec59..b815a4d2e1d6 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -686,6 +686,35 @@ static __always_inline void follow_dotdot(struct nameidata *nd)
 }
 
 /*
+ * 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.
  *  It _is_ time-critical.
@@ -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;
 }