generic_write_checks(): drop isblk argument

all remaining callers are passing 0; some just obscure that fact.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/btrfs/file.c b/fs/btrfs/file.c
index cdc801c..691a84a 100644
--- a/fs/btrfs/file.c
+++ b/fs/btrfs/file.c
@@ -1747,7 +1747,7 @@
 	mutex_lock(&inode->i_mutex);
 
 	current->backing_dev_info = inode_to_bdi(inode);
-	err = generic_write_checks(file, &pos, &count, S_ISBLK(inode->i_mode));
+	err = generic_write_checks(file, &pos, &count);
 	if (err) {
 		mutex_unlock(&inode->i_mutex);
 		goto out;