dm-ioctl: enhanced messages
This patch introduces enhanced message support that is needed for the
following statistics patch.
This patch allows processing of special messages in the device mapper in
the function "message_for_md". If the device mapper doesn't support the
message, it is passed to the target driver..
This patch allows two-way messages, that is messages that may return
some data. If the message returns data, the kernel signals it with
DM_MESSAGE_OUT_FLAG flag.
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
---
drivers/md/dm-ioctl.c | 55 +++++++++++++++++++++++++++++++++++++++++-
include/uapi/linux/dm-ioctl.h | 5 +++
2 files changed, 59 insertions(+), 1 deletion(-)
Index: linux-3.8-rc7-fast/drivers/md/dm-ioctl.c
===================================================================
--- linux-3.8-rc7-fast.orig/drivers/md/dm-ioctl.c 2013-02-14 23:31:21.000000000 +0100
+++ linux-3.8-rc7-fast/drivers/md/dm-ioctl.c 2013-02-14 23:42:59.000000000 +0100
@@ -1451,6 +1451,52 @@ static int table_status(struct dm_ioctl
return 0;
}
+struct dm_message_output_callback {
+ struct dm_ioctl *param;
+ size_t param_size;
+};
+
+static int dm_output_message_string(struct dm_message_output_callback *c,
+ const char *string)
+{
+ size_t len;
+ char *p;
+ if (c->param->flags & DM_BUFFER_FULL_FLAG)
+ return -1;
+ if (!(c->param->flags & DM_MESSAGE_OUT_FLAG)) {
+ p = get_result_buffer(c->param, c->param_size, &len);
+ if (!len) {
+ c->param->flags |= DM_BUFFER_FULL_FLAG;
+ return -1;
+ }
+ *p = 0;
+ c->param->data_size = c->param->data_start + 1;
+ c->param->flags |= DM_MESSAGE_OUT_FLAG;
+ }
+ p = (char *)c->param + c->param->data_size - 1;
+ len = strlen(string);
+ if (c->param->data_size + len > c->param_size) {
+ c->param->flags |= DM_BUFFER_FULL_FLAG;
+ c->param->flags &= ~DM_MESSAGE_OUT_FLAG;
+ return -1;
+ }
+ c->param->data_size += len;
+ strcpy(p, string);
+ return 0;
+}
+
+/*
+ * Process device-mapper dependent messages.
+ * Returns a number <= 0 if message was processed by device mapper.
+ * Returns 1 if message should be delivered to the target.
+ */
+static int message_for_md(struct mapped_device *md,
+ struct dm_message_output_callback *c,
+ unsigned argc, char **argv)
+{
+ return 1;
+}
+
/*
* Pass a message to the target that's at the supplied device offset.
*/
@@ -1463,6 +1509,7 @@ static int target_message(struct dm_ioct
struct dm_target *ti;
struct dm_target_msg *tmsg = (void *) param + param->data_start;
int srcu_idx;
+ struct dm_message_output_callback c = { param, param_size };
md = find_device(param);
if (!md)
@@ -1486,6 +1533,10 @@ static int target_message(struct dm_ioct
goto out_argv;
}
+ r = message_for_md(md, &c, argc, argv);
+ if (r <= 0)
+ goto out_argv;
+
table = dm_get_live_table(md, &srcu_idx);
if (!table)
goto out_table;
@@ -1511,7 +1562,8 @@ static int target_message(struct dm_ioct
out_argv:
kfree(argv);
out:
- param->data_size = 0;
+ if (!(param->flags & (DM_MESSAGE_OUT_FLAG | DM_BUFFER_FULL_FLAG)))
+ param->data_size = 0;
dm_put(md);
return r;
}
@@ -1685,6 +1737,7 @@ static int validate_params(uint cmd, str
param->flags &= ~DM_BUFFER_FULL_FLAG;
param->flags &= ~DM_UEVENT_GENERATED_FLAG;
param->flags &= ~DM_SECURE_DATA_FLAG;
+ param->flags &= ~DM_MESSAGE_OUT_FLAG;
/* Ignores parameters */
if (cmd == DM_REMOVE_ALL_CMD ||
Index: linux-3.8-rc7-fast/include/uapi/linux/dm-ioctl.h
===================================================================
--- linux-3.8-rc7-fast.orig/include/uapi/linux/dm-ioctl.h 2013-02-14 23:39:39.000000000 +0100
+++ linux-3.8-rc7-fast/include/uapi/linux/dm-ioctl.h 2013-02-14 23:40:39.000000000 +0100
@@ -336,4 +336,9 @@ enum {
*/
#define DM_SECURE_DATA_FLAG (1 << 15) /* In */
+/*
+ * If set, message generated output.
+ */
+#define DM_MESSAGE_OUT_FLAG (1 << 16) /* Out */
+
#endif /* _LINUX_DM_IOCTL_H */
--
dm-devel mailing list
dm-devel@xxxxxxxxxx
https://www.redhat.com/mailman/listinfo/dm-devel
