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/coda/file.c b/fs/coda/file.c
index 1da3805..f47c748 100644
--- a/fs/coda/file.c
+++ b/fs/coda/file.c
@@ -71,12 +71,12 @@
 
 	host_file = cfi->cfi_container;
 	file_start_write(host_file);
-	mutex_lock(&coda_inode->i_mutex);
+	inode_lock(coda_inode);
 	ret = vfs_iter_write(cfi->cfi_container, to, &iocb->ki_pos);
 	coda_inode->i_size = file_inode(host_file)->i_size;
 	coda_inode->i_blocks = (coda_inode->i_size + 511) >> 9;
 	coda_inode->i_mtime = coda_inode->i_ctime = CURRENT_TIME_SEC;
-	mutex_unlock(&coda_inode->i_mutex);
+	inode_unlock(coda_inode);
 	file_end_write(host_file);
 	return ret;
 }
@@ -203,7 +203,7 @@
 	err = filemap_write_and_wait_range(coda_inode->i_mapping, start, end);
 	if (err)
 		return err;
-	mutex_lock(&coda_inode->i_mutex);
+	inode_lock(coda_inode);
 
 	cfi = CODA_FTOC(coda_file);
 	BUG_ON(!cfi || cfi->cfi_magic != CODA_MAGIC);
@@ -212,7 +212,7 @@
 	err = vfs_fsync(host_file, datasync);
 	if (!err && !datasync)
 		err = venus_fsync(coda_inode->i_sb, coda_i2f(coda_inode));
-	mutex_unlock(&coda_inode->i_mutex);
+	inode_unlock(coda_inode);
 
 	return err;
 }