From 01345021a4a9800f1248bd37036ccd5edfb009c9 Mon Sep 17 00:00:00 2001
From: Fabian Keil <fk@fabiankeil.de>
Date: Mon, 27 Apr 2015 19:53:30 +0200
Subject: [PATCH 030/257] ggate[cd]: Add BIO_FLUSH support

Let ggated transform BIO_FLUSH requests into fsync() calls.


Obtained from: ElectroBSD
---
 sbin/ggate/ggatec/ggatec.c |  8 +++++++-
 sbin/ggate/ggated/ggated.c | 23 ++++++++++++++++++-----
 sbin/ggate/shared/ggate.h  |  1 +
 3 files changed, 26 insertions(+), 6 deletions(-)

diff --git a/sbin/ggate/ggatec/ggatec.c b/sbin/ggate/ggatec/ggatec.c
index 650e4f585d54..f91c172effb2 100644
--- a/sbin/ggate/ggatec/ggatec.c
+++ b/sbin/ggate/ggatec/ggatec.c
@@ -146,6 +146,11 @@ send_thread(void *arg __unused)
 		case BIO_WRITE:
 			hdr.gh_cmd = GGATE_CMD_WRITE;
 			break;
+		case BIO_FLUSH:
+			g_gate_log(LOG_DEBUG, "FLUSH request");
+			hdr.gh_cmd = GGATE_CMD_FLUSH;
+			assert(ggio.gctl_length == 0);
+			break;
 		default:
 			g_gate_log(LOG_ERR,
 			    "Rejecting unsupported BIO command: %d",
@@ -228,7 +233,8 @@ recv_thread(void *arg __unused)
 		ggio.gctl_error = hdr.gh_error;
 
 		if (ggio.gctl_cmd != GGATE_CMD_READ &&
-		    ggio.gctl_cmd != GGATE_CMD_WRITE) {
+		    ggio.gctl_cmd != GGATE_CMD_WRITE &&
+		    ggio.gctl_cmd != GGATE_CMD_FLUSH) {
 			g_gate_xlog("Unexpected GGATE_CMD: %d", ggio.gctl_cmd);
 		}
 
diff --git a/sbin/ggate/ggated/ggated.c b/sbin/ggate/ggated/ggated.c
index 22810b0a00fd..2adbb68f7a83 100644
--- a/sbin/ggate/ggated/ggated.c
+++ b/sbin/ggate/ggated/ggated.c
@@ -657,8 +657,10 @@ recv_thread(void *arg)
 		 * Reject requests that violate assertions in disk_thread().
 		 */
 		if (req->r_cmd != GGATE_CMD_READ &&
-		    req->r_cmd != GGATE_CMD_WRITE) {
-			g_gate_xlog("Request contains invalid command.");
+		    req->r_cmd != GGATE_CMD_WRITE &&
+		    req->r_cmd != GGATE_CMD_FLUSH) {
+			g_gate_xlog("Request contains invalid command: %d",
+			    req->r_cmd);
 		}
 		if (req->r_offset + req->r_length >
 		    (uintmax_t)conn->c_mediasize) {
@@ -681,9 +683,10 @@ recv_thread(void *arg)
 		}
 
 		/*
-		 * Allocate memory for data.
+		 * Allocate memory for data, except when flushing.
 		 */
-		req->r_data = malloc_waitok(req->r_length);
+		req->r_data = req->r_cmd != GGATE_CMD_FLUSH ?
+                    malloc_waitok(req->r_length) : NULL;
 
 		/*
 		 * Receive data to write for WRITE request.
@@ -743,7 +746,9 @@ disk_thread(void *arg)
 		/*
 		 * Check the request.
 		 */
-		assert(req->r_cmd == GGATE_CMD_READ || req->r_cmd == GGATE_CMD_WRITE);
+		assert(req->r_cmd == GGATE_CMD_READ ||
+		    req->r_cmd == GGATE_CMD_WRITE ||
+		    req->r_cmd == GGATE_CMD_FLUSH);
 		assert(req->r_offset + req->r_length <= (uintmax_t)conn->c_mediasize);
 		assert((req->r_offset % conn->c_sectorsize) == 0);
 		assert((req->r_length % conn->c_sectorsize) == 0);
@@ -767,6 +772,14 @@ disk_thread(void *arg)
 			free(req->r_data);
 			req->r_data = NULL;
 			break;
+		case GGATE_CMD_FLUSH:
+			g_gate_log(LOG_DEBUG, "Flushing");
+			if (fsync(fd)) {
+				req->r_error = errno;
+				g_gate_log(LOG_ERR, "Flushing failed: %s",
+				    strerror(errno));
+			}
+			break;
 		}
 		if (data != (ssize_t)req->r_length) {
 			/* Report short reads/writes as I/O errors. */
diff --git a/sbin/ggate/shared/ggate.h b/sbin/ggate/shared/ggate.h
index 898efea6507e..52985660def6 100644
--- a/sbin/ggate/shared/ggate.h
+++ b/sbin/ggate/shared/ggate.h
@@ -55,6 +55,7 @@
 
 #define	GGATE_CMD_READ		0
 #define	GGATE_CMD_WRITE		1
+#define	GGATE_CMD_FLUSH		2
 
 extern int g_gate_devfd;
 extern int g_gate_verbose;
-- 
2.11.0