ovl: remove the 'locked' argument of ovl_nlink_{start,end}

It just makes the interface strange without adding any significant value.
The only case where locked is false and return value is 0 is in
ovl_rename() when new is negative, so handle that case explicitly in
ovl_rename().

Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/dir.c

@@ -652,7 +652,6 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
 		    struct dentry *new)
 {
 	int err;
-	bool locked = false;
 	struct inode *inode;
 
 	err = ovl_want_write(old);
@@ -673,7 +672,7 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
 			goto out_drop_write;
 	}
 
-	err = ovl_nlink_start(old, &locked);
+	err = ovl_nlink_start(old);
 	if (err)
 		goto out_drop_write;
 
@@ -686,7 +685,7 @@ static int ovl_link(struct dentry *old, struct inode *newdir,
 	if (err)
 		iput(inode);
 
-	ovl_nlink_end(old, locked);
+	ovl_nlink_end(old);
 out_drop_write:
 	ovl_drop_write(old);
 out:
@@ -811,7 +810,6 @@ static bool ovl_pure_upper(struct dentry *dentry)
 static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 {
 	int err;
-	bool locked = false;
 	const struct cred *old_cred;
 	struct dentry *upperdentry;
 	bool lower_positive = ovl_lower_positive(dentry);
@@ -832,7 +830,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 	if (err)
 		goto out_drop_write;
 
-	err = ovl_nlink_start(dentry, &locked);
+	err = ovl_nlink_start(dentry);
 	if (err)
 		goto out_drop_write;
 
@@ -848,7 +846,7 @@ static int ovl_do_remove(struct dentry *dentry, bool is_dir)
 		else
 			drop_nlink(dentry->d_inode);
 	}
-	ovl_nlink_end(dentry, locked);
+	ovl_nlink_end(dentry);
 
 	/*
 	 * Copy ctime
@@ -1012,7 +1010,6 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 		      unsigned int flags)
 {
 	int err;
-	bool locked = false;
 	struct dentry *old_upperdir;
 	struct dentry *new_upperdir;
 	struct dentry *olddentry;
@@ -1021,6 +1018,7 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 	bool old_opaque;
 	bool new_opaque;
 	bool cleanup_whiteout = false;
+	bool update_nlink = false;
 	bool overwrite = !(flags & RENAME_EXCHANGE);
 	bool is_dir = d_is_dir(old);
 	bool new_is_dir = d_is_dir(new);
@@ -1078,10 +1076,12 @@ static int ovl_rename(struct inode *olddir, struct dentry *old,
 		err = ovl_copy_up(new);
 		if (err)
 			goto out_drop_write;
-	} else {
-		err = ovl_nlink_start(new, &locked);
+	} else if (d_inode(new)) {
+		err = ovl_nlink_start(new);
 		if (err)
 			goto out_drop_write;
+
+		update_nlink = true;
 	}
 
 	old_cred = ovl_override_creds(old->d_sb);
@@ -1210,7 +1210,8 @@ out_unlock:
 	unlock_rename(new_upperdir, old_upperdir);
 out_revert_creds:
 	revert_creds(old_cred);
-	ovl_nlink_end(new, locked);
+	if (update_nlink)
+		ovl_nlink_end(new);
 out_drop_write:
 	ovl_drop_write(old);
 out:

fs/overlayfs/overlayfs.h

@@ -271,8 +271,8 @@ bool ovl_test_flag(unsigned long flag, struct inode *inode);
 bool ovl_inuse_trylock(struct dentry *dentry);
 void ovl_inuse_unlock(struct dentry *dentry);
 bool ovl_need_index(struct dentry *dentry);
-int ovl_nlink_start(struct dentry *dentry, bool *locked);
-void ovl_nlink_end(struct dentry *dentry, bool locked);
+int ovl_nlink_start(struct dentry *dentry);
+void ovl_nlink_end(struct dentry *dentry);
 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir);
 int ovl_check_metacopy_xattr(struct dentry *dentry);
 bool ovl_is_metacopy_dentry(struct dentry *dentry);

fs/overlayfs/util.c

@@ -738,14 +738,14 @@ fail:
  * Operations that change overlay inode and upper inode nlink need to be
  * synchronized with copy up for persistent nlink accounting.
  */
-int ovl_nlink_start(struct dentry *dentry, bool *locked)
+int ovl_nlink_start(struct dentry *dentry)
 {
 	struct ovl_inode *oi = OVL_I(d_inode(dentry));
 	const struct cred *old_cred;
 	int err;
 
-	if (!d_inode(dentry))
-		return 0;
+	if (WARN_ON(!d_inode(dentry)))
+		return -ENOENT;
 
 	/*
 	 * With inodes index is enabled, we store the union overlay nlink
@@ -787,15 +787,12 @@ int ovl_nlink_start(struct dentry *dentry, bool *locked)
 out:
 	if (err)
 		mutex_unlock(&oi->lock);
-	else
-		*locked = true;
 
 	return err;
 }
 
-void ovl_nlink_end(struct dentry *dentry, bool locked)
+void ovl_nlink_end(struct dentry *dentry)
 {
-	if (locked) {
 	if (ovl_test_flag(OVL_INDEX, d_inode(dentry)) &&
 	    d_inode(dentry)->i_nlink == 0) {
 		const struct cred *old_cred;
@@ -807,7 +804,6 @@ void ovl_nlink_end(struct dentry *dentry, bool locked)
 
 	mutex_unlock(&OVL_I(d_inode(dentry))->lock);
 }
-}
 
 int ovl_lock_rename_workdir(struct dentry *workdir, struct dentry *upperdir)
 {