From c834a7854be580c3b63d512b72eadcc8fd948c3e Mon Sep 17 00:00:00 2001
From: Fabian Keil <fk@fabiankeil.de>
Date: Tue, 5 May 2015 17:39:16 +0200
Subject: [PATCH 033/257] ggate[cd]: Add BIO_DELETE support

On the ggated side the requests are translated into writes of
zero which ZFS will convert into BIO_DELETE requests again when
zle compression is enabled.


Obtained from: ElectroBSD
---
 sbin/ggate/ggatec/ggatec.c |  5 +++++
 sbin/ggate/ggated/ggated.c | 47 +++++++++++++++++++++++++++++++++++++++-------
 sbin/ggate/shared/ggate.c  |  2 ++
 sbin/ggate/shared/ggate.h  |  1 +
 4 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/sbin/ggate/ggatec/ggatec.c b/sbin/ggate/ggatec/ggatec.c
index 4d0b12f940ee..e70cf553f359 100644
--- a/sbin/ggate/ggatec/ggatec.c
+++ b/sbin/ggate/ggatec/ggatec.c
@@ -146,6 +146,10 @@ send_thread(void *arg __unused)
 		case BIO_WRITE:
 			hdr.gh_cmd = GGATE_CMD_WRITE;
 			break;
+		case BIO_DELETE:
+			g_gate_log(LOG_DEBUG, "DELETE request");
+			hdr.gh_cmd = GGATE_CMD_DELETE;
+			break;
 		case BIO_FLUSH:
 			g_gate_log(LOG_DEBUG, "FLUSH request");
 			hdr.gh_cmd = GGATE_CMD_FLUSH;
@@ -237,6 +241,7 @@ recv_thread(void *arg __unused)
 
 		if (ggio.gctl_cmd != GGATE_CMD_READ &&
 		    ggio.gctl_cmd != GGATE_CMD_WRITE &&
+		    ggio.gctl_cmd != GGATE_CMD_DELETE &&
 		    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 fa11d8b90d13..c640b5798f69 100644
--- a/sbin/ggate/ggated/ggated.c
+++ b/sbin/ggate/ggated/ggated.c
@@ -636,6 +636,7 @@ recv_thread(void *arg)
 		 * Get header packet.
 		 */
 		req = malloc_waitok(sizeof(*req));
+		memset(req, 0, sizeof(*req));
 		data = g_gate_recv(fd, &req->r_hdr, sizeof(req->r_hdr),
 		    MSG_WAITALL);
 		if (data == 0) {
@@ -658,6 +659,7 @@ recv_thread(void *arg)
 		 */
 		if (req->r_cmd != GGATE_CMD_READ &&
 		    req->r_cmd != GGATE_CMD_WRITE &&
+		    req->r_cmd != GGATE_CMD_DELETE &&
 		    req->r_cmd != GGATE_CMD_FLUSH) {
 			g_gate_xlog("Request contains invalid command: %d",
 			    req->r_cmd);
@@ -677,21 +679,16 @@ recv_thread(void *arg)
 		 * the client. MAXPHYS is the hard limit in ggatec,
 		 * values above it are thus pretty suspicious.
 		 */
-		if (req->r_length > MAXPHYS) {
+		if (req->r_length > MAXPHYS && req->r_cmd != GGATE_CMD_DELETE) {
 			g_gate_xlog("Request length above MAXPHYS: %u > %u",
 			    (unsigned)req->r_length, MAXPHYS);
 		}
 
 		/*
-		 * Allocate memory for data, except when flushing.
-		 */
-		req->r_data = req->r_cmd != GGATE_CMD_FLUSH ?
-                    malloc_waitok(req->r_length) : NULL;
-
-		/*
 		 * Receive data to write for WRITE request.
 		 */
 		if (req->r_cmd == GGATE_CMD_WRITE) {
+			req->r_data = malloc_waitok(req->r_length);
 			g_gate_log(LOG_DEBUG, "Waiting for %u bytes of data...",
 			    req->r_length);
 			data = g_gate_recv(fd, req->r_data, req->r_length,
@@ -718,6 +715,34 @@ recv_thread(void *arg)
 	}
 }
 
+static ssize_t
+delete_range(int fd, size_t length, off_t offset)
+{
+	static char zeros[MAXPHYS];
+	size_t written;
+
+        written = 0;
+
+	do
+	{
+		int ret;
+		size_t bytes_left;
+		size_t chunk_size;
+
+		bytes_left = length - written;
+		chunk_size = bytes_left > MAXPHYS ? MAXPHYS : bytes_left;
+		ret = pwrite(fd, zeros, chunk_size, offset + written);
+		if (ret == -1)
+			return (written);
+		written += ret;
+	} while (written < length);
+
+	g_gate_log(LOG_DEBUG, "Overwritten %u bytes at offset %jd with zeros",
+	    written, (intmax_t)offset);
+
+	return (written);
+}
+
 static void *
 disk_thread(void *arg)
 {
@@ -748,6 +773,7 @@ disk_thread(void *arg)
 		 */
 		assert(req->r_cmd == GGATE_CMD_READ ||
 		    req->r_cmd == GGATE_CMD_WRITE ||
+		    req->r_cmd == GGATE_CMD_DELETE ||
 		    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);
@@ -763,9 +789,16 @@ disk_thread(void *arg)
 		data = 0;
 		switch (req->r_cmd) {
 		case GGATE_CMD_READ:
+			assert(req->r_data == NULL);
+			req->r_data = malloc_waitok(req->r_length);
 			data = pread(fd, req->r_data, req->r_length,
 			    req->r_offset);
 			break;
+		case GGATE_CMD_DELETE:
+			data = delete_range(fd, req->r_length,
+			    req->r_offset);
+			assert((size_t)data <= req->r_length);
+			break;
 		case GGATE_CMD_WRITE:
 			data = pwrite(fd, req->r_data, req->r_length,
 			    req->r_offset);
diff --git a/sbin/ggate/shared/ggate.c b/sbin/ggate/shared/ggate.c
index 05fc25a9afc0..7fe37cc0bc91 100644
--- a/sbin/ggate/shared/ggate.c
+++ b/sbin/ggate/shared/ggate.c
@@ -417,6 +417,8 @@ g_gate_cmd2str(int cmd)
 		return ("GGATE_CMD_READ");
 	case GGATE_CMD_WRITE:
 		return ("GGATE_CMD_WRITE");
+	case GGATE_CMD_DELETE:
+		return ("GGATE_CMD_DELETE");
 	case GGATE_CMD_FLUSH:
 		return ("GGATE_CMD_FLUSH");
 	}
diff --git a/sbin/ggate/shared/ggate.h b/sbin/ggate/shared/ggate.h
index 36565192a1a8..e5792e3c41e3 100644
--- a/sbin/ggate/shared/ggate.h
+++ b/sbin/ggate/shared/ggate.h
@@ -56,6 +56,7 @@
 #define	GGATE_CMD_READ		0
 #define	GGATE_CMD_WRITE		1
 #define	GGATE_CMD_FLUSH		2
+#define	GGATE_CMD_DELETE	3
 
 extern int g_gate_devfd;
 extern int g_gate_verbose;
-- 
2.11.0