dm: introduce merge_bvec_fn
Introduce a bvec merge function for device mapper devices
for dynamic size restrictions.
This code ensures the requested biovec lies within a single
target and then calls a target-specific function to check
against any constraints imposed by underlying devices.
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 0d8d419..a90222e 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -9,11 +9,13 @@
#define _LINUX_DEVICE_MAPPER_H
#include <linux/bio.h>
+#include <linux/blkdev.h>
struct dm_target;
struct dm_table;
struct dm_dev;
struct mapped_device;
+struct bio_vec;
typedef enum { STATUSTYPE_INFO, STATUSTYPE_TABLE } status_type_t;
@@ -72,6 +74,9 @@
struct file *filp, unsigned int cmd,
unsigned long arg);
+typedef int (*dm_merge_fn) (struct dm_target *ti, struct bvec_merge_data *bvm,
+ struct bio_vec *biovec, int max_size);
+
void dm_error(const char *message);
/*
@@ -107,6 +112,7 @@
dm_status_fn status;
dm_message_fn message;
dm_ioctl_fn ioctl;
+ dm_merge_fn merge;
};
struct io_restrictions {