Use ioemu block drivers through blktap.

Add support for a tap:ioemu pseudo driver. Devices using this driver
won't use tapdisk (containing the code duplication) any more, but will
connect to the qemu-dm of the domain. In this way no working
configuration should be broken right now as you can still choose to
use the tapdisk drivers.

Signed-off-by: Kevin Wolf <kwolf@suse.de>

3 files changed, 92 insertions, 32 deletions

diff --git a/tools/blktap/drivers/blktapctrl.c b/tools/blktap/drivers/blktapctrl.c
index 8cbf185f03..8825e919c4 100644
--- a/tools/blktap/drivers/blktapctrl.c
+++ b/tools/blktap/drivers/blktapctrl.c
@@ -501,6 +501,80 @@ int launch_tapdisk(char *wrctldev, char *rdctldev)
 	return 0;
 }
 
+/* Connect to qemu-dm */
+static int connect_qemu(blkif_t *blkif)
+{
+	char *rdctldev, *wrctldev;
+	
+	if (asprintf(&rdctldev, BLKTAP_CTRL_DIR "/qemu-read-%d", 
+			blkif->domid) < 0)
+		return -1;
+
+	if (asprintf(&wrctldev, BLKTAP_CTRL_DIR "/qemu-write-%d", 
+			blkif->domid) < 0) {
+		free(rdctldev);
+		return -1;
+	}
+
+	DPRINTF("Using qemu blktap pipe: %s\n", rdctldev);
+	
+	blkif->fds[READ] = open_ctrl_socket(wrctldev);
+	blkif->fds[WRITE] = open_ctrl_socket(rdctldev);
+	
+	free(rdctldev);
+	free(wrctldev);
+	
+	if (blkif->fds[READ] == -1 || blkif->fds[WRITE] == -1)
+		return -1;
+
+	DPRINTF("Attached to qemu blktap pipes\n");
+	return 0;
+}
+
+/* Launch tapdisk instance */
+static int connect_tapdisk(blkif_t *blkif, int minor)
+{
+	char *rdctldev = NULL, *wrctldev = NULL;
+	int ret = -1;
+
+	DPRINTF("tapdisk process does not exist:\n");
+
+	if (asprintf(&rdctldev,
+		     "%s/tapctrlread%d", BLKTAP_CTRL_DIR, minor) == -1)
+		goto fail;
+
+	if (asprintf(&wrctldev,
+		     "%s/tapctrlwrite%d", BLKTAP_CTRL_DIR, minor) == -1)
+		goto fail;
+	
+	blkif->fds[READ] = open_ctrl_socket(rdctldev);
+	blkif->fds[WRITE] = open_ctrl_socket(wrctldev);
+	
+	if (blkif->fds[READ] == -1 || blkif->fds[WRITE] == -1)
+		goto fail;
+
+	/*launch the new process*/
+	DPRINTF("Launching process, CMDLINE [tapdisk %s %s]\n",
+			wrctldev, rdctldev);
+
+	if (launch_tapdisk(wrctldev, rdctldev) == -1) {
+		DPRINTF("Unable to fork, cmdline: [tapdisk %s %s]\n",
+				wrctldev, rdctldev);
+		goto fail;
+	}
+
+	ret = 0;
+	
+fail:
+	if (rdctldev)
+		free(rdctldev);
+
+	if (wrctldev)
+		free(wrctldev);
+
+	return ret;
+}
+
 int blktapctrl_new_blkif(blkif_t *blkif)
 {
 	blkif_info_t *blk;
@@ -524,30 +598,14 @@ int blktapctrl_new_blkif(blkif_t *blkif)
 		blkif->cookie = next_cookie++;
 
 		if (!exist) {
-			DPRINTF("Process does not exist:\n");
-			if (asprintf(&rdctldev,
-				     "%s/tapctrlread%d", BLKTAP_CTRL_DIR, minor) == -1)
-				goto fail;
-			if (asprintf(&wrctldev,
-				     "%s/tapctrlwrite%d", BLKTAP_CTRL_DIR, minor) == -1) {
-				free(rdctldev);
-				goto fail;
-			}
-			blkif->fds[READ] = open_ctrl_socket(rdctldev);
-			blkif->fds[WRITE] = open_ctrl_socket(wrctldev);
-			
-			if (blkif->fds[READ] == -1 || blkif->fds[WRITE] == -1) 
-				goto fail;
-
-			/*launch the new process*/
- 			DPRINTF("Launching process, CMDLINE [tapdisk %s %s]\n",wrctldev, rdctldev);
- 			if (launch_tapdisk(wrctldev, rdctldev) == -1) {
- 				DPRINTF("Unable to fork, cmdline: [tapdisk %s %s]\n",wrctldev, rdctldev);
-				goto fail;
+			if (type == DISK_TYPE_IOEMU) {
+				if (connect_qemu(blkif))
+					goto fail;
+			} else {
+				if (connect_tapdisk(blkif, minor))
+					goto fail;
 			}
 
-			free(rdctldev);
-			free(wrctldev);
 		} else {
 			DPRINTF("Process exists!\n");
 			blkif->fds[READ] = exist->fds[READ];
diff --git a/tools/blktap/drivers/tapdisk.h b/tools/blktap/drivers/tapdisk.h
index 7b11d775de..77b7fd8c83 100644
--- a/tools/blktap/drivers/tapdisk.h
+++ b/tools/blktap/drivers/tapdisk.h
@@ -167,6 +167,7 @@ extern struct tap_disk tapdisk_qcow2;
 #define DISK_TYPE_RAM      3
 #define DISK_TYPE_QCOW     4
 #define DISK_TYPE_QCOW2    5
+#define DISK_TYPE_IOEMU    6
 
 
 /*Define Individual Disk Parameters here */
@@ -230,6 +231,16 @@ static disk_info_t qcow2_disk = {
 #endif
 };
 
+static disk_info_t ioemu_disk = {
+	DISK_TYPE_IOEMU,
+	"ioemu disk",
+	"ioemu",
+	0,
+#ifdef TAPDISK
+	NULL
+#endif
+};
+
 /*Main disk info array */
 static disk_info_t *dtypes[] = {
 	&aio_disk,
@@ -238,6 +249,7 @@ static disk_info_t *dtypes[] = {
 	&ram_disk,
 	&qcow_disk,
 	&qcow2_disk,
+	&ioemu_disk,
 };
 
 typedef struct driver_list_entry {
diff --git a/tools/blktap/lib/blktaplib.h b/tools/blktap/lib/blktaplib.h
index d31a7fac92..77aca53651 100644
--- a/tools/blktap/lib/blktaplib.h
+++ b/tools/blktap/lib/blktaplib.h
@@ -221,15 +221,5 @@ int xs_fire_next_watch(struct xs_handle *h);
      ((_req) * BLKIF_MAX_SEGMENTS_PER_REQUEST * getpagesize()) +    \
      ((_seg) * getpagesize()))
 
-/* Defines that are only used by library clients */
-
-#ifndef __COMPILING_BLKTAP_LIB
-
-static char *blkif_op_name[] = {
-	[BLKIF_OP_READ]       = "READ",
-	[BLKIF_OP_WRITE]      = "WRITE",
-};
-
-#endif /* __COMPILING_BLKTAP_LIB */
 
 #endif /* __BLKTAPLIB_H__ */