dm: support non power of two target max_io_len
Remove the restriction that limits a target's specified maximum incoming
I/O size to be a power of 2.
Rename this setting from 'split_io' to the less-ambiguous 'max_io_len'.
Change it from sector_t to uint32_t, which is plenty big enough, and
introduce a wrapper function dm_set_target_max_io_len() to set it.
Use sector_div() to process it now that it is not necessarily a power of 2.
Signed-off-by: Mike Snitzer <snitzer@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 d70cbb2..b19c1e1 100644
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -186,8 +186,8 @@
sector_t begin;
sector_t len;
- /* Always a power of 2 */
- sector_t split_io;
+ /* If non-zero, maximum size of I/O submitted to a target. */
+ uint32_t max_io_len;
/*
* A number of zero-length barrier requests that will be submitted
@@ -358,6 +358,11 @@
int dm_table_complete(struct dm_table *t);
/*
+ * Target may require that it is never sent I/O larger than len.
+ */
+int __must_check dm_set_target_max_io_len(struct dm_target *ti, sector_t len);
+
+/*
* Table reference counting.
*/
struct dm_table *dm_get_live_table(struct mapped_device *md);
diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index 75fd557..3ece4ee 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -268,8 +268,8 @@
#define DM_VERSION_MAJOR 4
#define DM_VERSION_MINOR 22
-#define DM_VERSION_PATCHLEVEL 0
-#define DM_VERSION_EXTRA "-ioctl (2011-10-19)"
+#define DM_VERSION_PATCHLEVEL 1
+#define DM_VERSION_EXTRA "-ioctl (2012-06-01)"
/* Status bits */
#define DM_READONLY_FLAG (1 << 0) /* In/Out */