Re: [PATCH 2/5] block: add function to issue compare and write

[Christoph Hellwig <hch@infradead.org>]

On Thu, Oct 16, 2014 at 12:37:12AM -0500, michaelc@cs.wisc.edu wrote:
> @@ -160,7 +160,7 @@ enum rq_flag_bits {
>  	__REQ_DISCARD,		/* request to discard sectors */
>  	__REQ_SECURE,		/* secure discard (used with __REQ_DISCARD) */
>  	__REQ_WRITE_SAME,	/* write same block many times */
> -
> +	__REQ_CMP_AND_WRITE,	/* compare data and write if matched */

I think it's time that we stop overloading the request flags with
request types.

We already have req->cmd_type which actually is a fairly good
description of what we get except for REQ_TYPE_FS, which is a horrible
overload using req->cmd_flags.

Given that you're just one of many currently ongoing patches to add
more flags here I think you need to byte the bullet and fix this up
by replacing REQ_TYPE_FS with:

REQ_TYPE_WRITE
REQ_TYPE_READ
REQ_TYPE_FLUSH
REQ_TYPE_DISCARD
REQ_TYPE_WRITE_SAME
REQ_TYPE_CMP_AND_WRITE

sd.c is a nice guide of what should be a flag and what a type since my
last refactoring of the command_init function.