From owner-svn-src-all@FreeBSD.ORG  Sat Mar 23 16:55:08 2013
Return-Path: <owner-svn-src-all@FreeBSD.ORG>
Delivered-To: svn-src-all@freebsd.org
Received: from mx1.freebsd.org (mx1.FreeBSD.org [8.8.178.115])
 by hub.freebsd.org (Postfix) with ESMTP id 9474F2989;
 Sat, 23 Mar 2013 16:55:08 +0000 (UTC)
 (envelope-from will@FreeBSD.org)
Received: from svn.freebsd.org (svn.freebsd.org
 [IPv6:2001:1900:2254:2068::e6a:0])
 by mx1.freebsd.org (Postfix) with ESMTP id 87467E28;
 Sat, 23 Mar 2013 16:55:08 +0000 (UTC)
Received: from svn.freebsd.org ([127.0.1.70])
 by svn.freebsd.org (8.14.6/8.14.6) with ESMTP id r2NGt83P005590;
 Sat, 23 Mar 2013 16:55:08 GMT (envelope-from will@svn.freebsd.org)
Received: (from will@localhost)
 by svn.freebsd.org (8.14.6/8.14.5/Submit) id r2NGt8uK005589;
 Sat, 23 Mar 2013 16:55:08 GMT (envelope-from will@svn.freebsd.org)
Message-Id: <201303231655.r2NGt8uK005589@svn.freebsd.org>
From: Will Andrews <will@FreeBSD.org>
Date: Sat, 23 Mar 2013 16:55:08 +0000 (UTC)
To: src-committers@freebsd.org, svn-src-all@freebsd.org,
 svn-src-head@freebsd.org
Subject: svn commit: r248654 - head/sys/sys
X-SVN-Group: head
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
X-BeenThere: svn-src-all@freebsd.org
X-Mailman-Version: 2.1.14
Precedence: list
List-Id: "SVN commit messages for the entire src tree \(except for &quot;
 user&quot; and &quot; projects&quot; \)" <svn-src-all.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/svn-src-all>
List-Post: <mailto:svn-src-all@freebsd.org>
List-Help: <mailto:svn-src-all-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/svn-src-all>,
 <mailto:svn-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Sat, 23 Mar 2013 16:55:08 -0000

Author: will
Date: Sat Mar 23 16:55:07 2013
New Revision: 248654
URL: http://svnweb.freebsd.org/changeset/base/248654

Log:
  Be more explicit about what each bio_cmd & bio_flags value means.
  
  Reviewed by:	ken (mentor)

Modified:
  head/sys/sys/bio.h

Modified: head/sys/sys/bio.h
==============================================================================
--- head/sys/sys/bio.h	Sat Mar 23 16:34:56 2013	(r248653)
+++ head/sys/sys/bio.h	Sat Mar 23 16:55:07 2013	(r248654)
@@ -41,19 +41,23 @@
 #include <sys/queue.h>
 
 /* bio_cmd */
-#define BIO_READ	0x01
-#define BIO_WRITE	0x02
-#define BIO_DELETE	0x04
-#define BIO_GETATTR	0x08
-#define BIO_FLUSH	0x10
+#define BIO_READ	0x01	/* Read I/O data */
+#define BIO_WRITE	0x02	/* Write I/O data */
+#define BIO_DELETE	0x04	/* TRIM or free blocks, i.e. mark as unused */
+#define BIO_GETATTR	0x08	/* Get GEOM attributes of object */
+#define BIO_FLUSH	0x10	/* Commit outstanding I/O now */
 #define BIO_CMD0	0x20	/* Available for local hacks */
 #define BIO_CMD1	0x40	/* Available for local hacks */
 #define BIO_CMD2	0x80	/* Available for local hacks */
 
 /* bio_flags */
-#define BIO_ERROR	0x01
-#define BIO_DONE	0x02
-#define BIO_ONQUEUE	0x04
+#define BIO_ERROR	0x01	/* An error occurred processing this bio. */
+#define BIO_DONE	0x02	/* This bio is finished. */
+#define BIO_ONQUEUE	0x04	/* This bio is in a queue & not yet taken. */
+/*
+ * This bio must be executed after all previous bios in the queue have been
+ * executed, and before any successive bios can be executed.
+ */
 #define BIO_ORDERED	0x08
 #define	BIO_UNMAPPED	0x10
 #define	BIO_TRANSIENT_MAPPING	0x20