Revert "ovl: get_write_access() in truncate"

This reverts commit 03bea604.

Commit 4d0c5ba2 ("vfs: do get_write_access() on upper layer of
overlayfs") makes the writecount checks inside overlayfs superfluous, the
file is already copied up and write access acquired on the upper inode when
ovl_setattr is called with ATTR_SIZE.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>

fs/overlayfs/inode.c

@@ -64,27 +64,10 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
 	if (err)
 		goto out;
 
-	if (attr->ia_valid & ATTR_SIZE) {
-		struct inode *realinode = d_inode(ovl_dentry_real(dentry));
-
-		err = -ETXTBSY;
-		if (atomic_read(&realinode->i_writecount) < 0)
-			goto out_drop_write;
-	}
-
 	err = ovl_copy_up(dentry);
 	if (!err) {
-		struct inode *winode = NULL;
-
 		upperdentry = ovl_dentry_upper(dentry);
 
-		if (attr->ia_valid & ATTR_SIZE) {
-			winode = d_inode(upperdentry);
-			err = get_write_access(winode);
-			if (err)
-				goto out_drop_write;
-		}
-
 		if (attr->ia_valid & (ATTR_KILL_SUID|ATTR_KILL_SGID))
 			attr->ia_valid &= ~ATTR_MODE;
 
@@ -95,11 +78,7 @@ int ovl_setattr(struct dentry *dentry, struct iattr *attr)
 		if (!err)
 			ovl_copyattr(upperdentry->d_inode, dentry->d_inode);
 		inode_unlock(upperdentry->d_inode);
-
-		if (winode)
-			put_write_access(winode);
 	}
-out_drop_write:
 	ovl_drop_write(dentry);
 out:
 	return err;