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>

fs/nfsd/nfs4proc.c

@@ -55,10 +55,10 @@ nfsd4_security_inode_setsecctx(struct svc_fh *resfh, struct xdr_netobj *label, u
 	struct inode *inode = d_inode(resfh->fh_dentry);
 	int status;
 
-	mutex_lock(&inode->i_mutex);
+	inode_lock(inode);
 	status = security_inode_setsecctx(resfh->fh_dentry,
 		label->data, label->len);
-	mutex_unlock(&inode->i_mutex);
+	inode_unlock(inode);
 
 	if (status)
 		/*