Add .io_hints to 'struct target_type' to allow the I/O hints portion
(io_min and io_opt) of the 'struct queue_limits' to be set by each
target.
Expose dm-stripe target's topology I/O hints. This fix enables striped
DM devices to properly expose their I/O hints to userland via /sys.
Without this fix tools would not be able to reliably depend on the I/O
hints that the I/O topology infrastructure added in 2.6.31-rcX provides.
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Index: linux-2.6/drivers/md/dm-stripe.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-stripe.c
+++ linux-2.6/drivers/md/dm-stripe.c
@@ -329,6 +329,16 @@ static int stripe_iterate_devices(struct
return ret;
}
+static void stripe_io_hints(struct dm_target *ti,
+ struct queue_limits *limits)
+{
+ struct stripe_c *sc = ti->private;
+ unsigned chunk_size = (sc->chunk_mask + 1) << 9;
+
+ blk_limits_io_min(limits, chunk_size);
+ limits->io_opt = chunk_size * sc->stripes;
+}
+
static struct target_type stripe_target = {
.name = "striped",
.version = {1, 2, 0},
@@ -339,6 +349,7 @@ static struct target_type stripe_target
.end_io = stripe_end_io,
.status = stripe_status,
.iterate_devices = stripe_iterate_devices,
+ .io_hints = stripe_io_hints,
};
int __init dm_stripe_init(void)
Index: linux-2.6/drivers/md/dm-table.c
===================================================================
--- linux-2.6.orig/drivers/md/dm-table.c
+++ linux-2.6/drivers/md/dm-table.c
@@ -996,6 +996,10 @@ int dm_calculate_queue_limits(struct dm_
ti->type->iterate_devices(ti, dm_set_device_limits,
&ti_limits);
+ /* Set I/O hints portion of queue limits */
+ if (ti->type->io_hints)
+ ti->type->io_hints(ti, &ti_limits);
+
/*
* Check each device area is consistent with the target's
* overall queue limits.
Index: linux-2.6/include/linux/device-mapper.h
===================================================================
--- linux-2.6.orig/include/linux/device-mapper.h
+++ linux-2.6/include/linux/device-mapper.h
@@ -91,6 +91,9 @@ typedef int (*dm_iterate_devices_fn) (st
iterate_devices_callout_fn fn,
void *data);
+typedef void (*dm_io_hints_fn) (struct dm_target *ti,
+ struct queue_limits *limits);
+
/*
* Returns:
* 0: The target can handle the next I/O immediately.
@@ -151,6 +154,7 @@ struct target_type {
dm_merge_fn merge;
dm_busy_fn busy;
dm_iterate_devices_fn iterate_devices;
+ dm_io_hints_fn io_hints;
/* For internal device-mapper use. */
struct list_head list;
--
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