[RFC Patch v3 14/22] switch to unprotected mode before closing

[Wen Congyang <wency@cn.fujitsu.com>]

If the user wants to stop tapdisk2, he will do
the following thing:
1. close the image
2. detach from blktap device

If there is some pending I/O request, close will
fail. But the I/O request is pended in remus until
the connection is established. Introduce a new
callback td_pre_close() to flush these I/O requests.

Signed-off-by: Wen Congyang <wency@cn.fujitsu.com>
Cc: Shriram Rajagopalan <rshriram@cs.ubc.ca>
---
 tools/blktap2/drivers/block-remus.c       | 15 +++++++++++++++
 tools/blktap2/drivers/tapdisk-control.c   |  6 ++++++
 tools/blktap2/drivers/tapdisk-interface.c | 18 ++++++++++++++++++
 tools/blktap2/drivers/tapdisk-interface.h |  1 +
 tools/blktap2/drivers/tapdisk-vbd.c       |  9 +++++++++
 tools/blktap2/drivers/tapdisk-vbd.h       |  1 +
 tools/blktap2/drivers/tapdisk.h           |  1 +
 7 files changed, 51 insertions(+)

diff --git a/tools/blktap2/drivers/block-remus.c b/tools/blktap2/drivers/block-remus.c
index c21f851..5d27d41 100644
--- a/tools/blktap2/drivers/block-remus.c
+++ b/tools/blktap2/drivers/block-remus.c
@@ -96,6 +96,7 @@ enum {
 	ERROR_INTERNAL = -1,
 	ERROR_IO = -2,
 	ERROR_CONNECTION = -3,
+	ERROR_CLOSE = -4,
 };
 
 struct tdremus_req {
@@ -810,6 +811,8 @@ static void primary_failed(struct tdremus_state *s, int rc)
 	close_stream_fd(s);
 	if (rc == ERROR_INTERNAL)
 		RPRINTF("switch to unprotected mode due to internal error");
+	if (rc == ERROR_CLOSE)
+		RPRINTF("switch to unprotected mode before closing");
 	switch_mode(s->tdremus_driver, mode_unprotected);
 }
 
@@ -1910,6 +1913,17 @@ static int tdremus_open(td_driver_t *driver, td_image_t *image, td_uuid_t uuid)
 	return -EIO;
 }
 
+static int tdremus_pre_close(td_driver_t *driver)
+{
+	struct tdremus_state *s = (struct tdremus_state *)driver->data;
+
+	if (s->mode != mode_primary)
+		return 0;
+
+	primary_failed(s, ERROR_CLOSE);
+	return 0;
+}
+
 static int tdremus_close(td_driver_t *driver)
 {
 	struct tdremus_state *s = (struct tdremus_state *)driver->data;
@@ -1944,6 +1958,7 @@ struct tap_disk tapdisk_remus = {
 	.td_open            = tdremus_open,
 	.td_queue_read      = unprotected_queue_read,
 	.td_queue_write     = unprotected_queue_write,
+	.td_pre_close       = tdremus_pre_close,
 	.td_close           = tdremus_close,
 	.td_get_parent_id   = tdremus_get_parent_id,
 	.td_validate_parent = tdremus_validate_parent,
diff --git a/tools/blktap2/drivers/tapdisk-control.c b/tools/blktap2/drivers/tapdisk-control.c
index 4e5f748..2fa4cbe 100644
--- a/tools/blktap2/drivers/tapdisk-control.c
+++ b/tools/blktap2/drivers/tapdisk-control.c
@@ -508,6 +508,12 @@ tapdisk_control_close_image(struct tapdisk_control_connection *connection,
 		goto out;
 	}
 
+	/*
+	 * Some I/O requests are pended in the driver, and
+	 * flush these requests first.
+	 */
+	tapdisk_vbd_pre_close_vdi(vbd);
+
 	if (!list_empty(&vbd->pending_requests)) {
 		err = -EAGAIN;
 		goto out;
diff --git a/tools/blktap2/drivers/tapdisk-interface.c b/tools/blktap2/drivers/tapdisk-interface.c
index a29de64..ed92e12 100644
--- a/tools/blktap2/drivers/tapdisk-interface.c
+++ b/tools/blktap2/drivers/tapdisk-interface.c
@@ -105,6 +105,24 @@ td_open(td_image_t *image)
 }
 
 int
+td_pre_close(td_image_t *image)
+{
+	td_driver_t *driver;
+
+	driver = image->driver;
+	if (!driver)
+		return -ENODEV;
+
+	if (!driver->ops->td_pre_close)
+		return 0;
+
+	if (driver->refcnt && td_flag_test(driver->state, TD_DRIVER_OPEN))
+		driver->ops->td_pre_close(driver);
+
+	return 0;
+}
+
+int
 td_close(td_image_t *image)
 {
 	td_driver_t *driver;
diff --git a/tools/blktap2/drivers/tapdisk-interface.h b/tools/blktap2/drivers/tapdisk-interface.h
index adc4376..ba9b3ea 100644
--- a/tools/blktap2/drivers/tapdisk-interface.h
+++ b/tools/blktap2/drivers/tapdisk-interface.h
@@ -34,6 +34,7 @@
 int td_open(td_image_t *);
 int __td_open(td_image_t *, td_disk_info_t *);
 int td_load(td_image_t *);
+int td_pre_close(td_image_t *);
 int td_close(td_image_t *);
 int td_get_parent_id(td_image_t *, td_disk_id_t *);
 int td_validate_parent(td_image_t *, td_image_t *);
diff --git a/tools/blktap2/drivers/tapdisk-vbd.c b/tools/blktap2/drivers/tapdisk-vbd.c
index c665f27..aba545b 100644
--- a/tools/blktap2/drivers/tapdisk-vbd.c
+++ b/tools/blktap2/drivers/tapdisk-vbd.c
@@ -180,6 +180,15 @@ tapdisk_vbd_validate_chain(td_vbd_t *vbd)
 }
 
 void
+tapdisk_vbd_pre_close_vdi(td_vbd_t *vbd)
+{
+	td_image_t *image, *tmp;
+
+	tapdisk_vbd_for_each_image(vbd, image, tmp)
+		td_pre_close(image);
+}
+
+void
 tapdisk_vbd_close_vdi(td_vbd_t *vbd)
 {
 	td_image_t *image, *tmp;
diff --git a/tools/blktap2/drivers/tapdisk-vbd.h b/tools/blktap2/drivers/tapdisk-vbd.h
index be084b2..040f2b8 100644
--- a/tools/blktap2/drivers/tapdisk-vbd.h
+++ b/tools/blktap2/drivers/tapdisk-vbd.h
@@ -181,6 +181,7 @@ void tapdisk_vbd_free_stack(td_vbd_t *);
 int tapdisk_vbd_open_stack(td_vbd_t *, uint16_t, td_flag_t);
 int tapdisk_vbd_open_vdi(td_vbd_t *, const char *,
 			 uint16_t, uint16_t, td_flag_t);
+void tapdisk_vbd_pre_close_vdi(td_vbd_t *);
 void tapdisk_vbd_close_vdi(td_vbd_t *);
 
 int tapdisk_vbd_attach(td_vbd_t *, const char *, int);
diff --git a/tools/blktap2/drivers/tapdisk.h b/tools/blktap2/drivers/tapdisk.h
index 3c3b51d..16efd07 100644
--- a/tools/blktap2/drivers/tapdisk.h
+++ b/tools/blktap2/drivers/tapdisk.h
@@ -158,6 +158,7 @@ struct tap_disk {
 	td_flag_t                    flags;
 	int                          private_data_size;
 	int (*td_open)               (td_driver_t *, td_image_t *, td_uuid_t);
+	int (*td_pre_close)          (td_driver_t *);
 	int (*td_close)              (td_driver_t *);
 	int (*td_get_parent_id)      (td_driver_t *, td_disk_id_t *);
 	int (*td_validate_parent)    (td_driver_t *, td_driver_t *, td_flag_t);
-- 
1.9.3