acme: add comment for aligned writes
TBR=r
https://codereview.appspot.com/89510044
diff --git a/src/cmd/acme/exec.c b/src/cmd/acme/exec.c
index 0ef6684..6f8bf3f 100644
--- a/src/cmd/acme/exec.c
+++ b/src/cmd/acme/exec.c
@@ -662,6 +662,11 @@
warning(nil, "can't create file %s: %r\n", name);
goto Rescue1;
}
+ // Use bio in order to force the writes to be large and
+ // block-aligned (bio's default is 8K). This is not strictly
+ // necessary; it works around some buggy underlying
+ // file systems that mishandle unaligned writes.
+ // https://codereview.appspot.com/89550043/
b = emalloc(sizeof *b);
Binit(b, fd, OWRITE);
r = fbufalloc();
