wrappers for ->i_mutex access

parallel to mutex_{lock,unlock,trylock,is_locked,lock_nested},
inode_foo(inode) being mutex_foo(&inode->i_mutex).

Please, use those for access to ->i_mutex; over the coming cycle
->i_mutex will become rwsem, with ->lookup() done with it held
only shared.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/exportfs/expfs.c b/fs/exportfs/expfs.c
index 714cd37..c46f1a1 100644
--- a/fs/exportfs/expfs.c
+++ b/fs/exportfs/expfs.c
@@ -124,10 +124,10 @@
 	int err;
 
 	parent = ERR_PTR(-EACCES);
-	mutex_lock(&dentry->d_inode->i_mutex);
+	inode_lock(dentry->d_inode);
 	if (mnt->mnt_sb->s_export_op->get_parent)
 		parent = mnt->mnt_sb->s_export_op->get_parent(dentry);
-	mutex_unlock(&dentry->d_inode->i_mutex);
+	inode_unlock(dentry->d_inode);
 
 	if (IS_ERR(parent)) {
 		dprintk("%s: get_parent of %ld failed, err %d\n",
@@ -143,9 +143,9 @@
 	if (err)
 		goto out_err;
 	dprintk("%s: found name: %s\n", __func__, nbuf);
-	mutex_lock(&parent->d_inode->i_mutex);
+	inode_lock(parent->d_inode);
 	tmp = lookup_one_len(nbuf, parent, strlen(nbuf));
-	mutex_unlock(&parent->d_inode->i_mutex);
+	inode_unlock(parent->d_inode);
 	if (IS_ERR(tmp)) {
 		dprintk("%s: lookup failed: %d\n", __func__, PTR_ERR(tmp));
 		goto out_err;
@@ -503,10 +503,10 @@
 		 */
 		err = exportfs_get_name(mnt, target_dir, nbuf, result);
 		if (!err) {
-			mutex_lock(&target_dir->d_inode->i_mutex);
+			inode_lock(target_dir->d_inode);
 			nresult = lookup_one_len(nbuf, target_dir,
 						 strlen(nbuf));
-			mutex_unlock(&target_dir->d_inode->i_mutex);
+			inode_unlock(target_dir->d_inode);
 			if (!IS_ERR(nresult)) {
 				if (nresult->d_inode) {
 					dput(result);