dm stripe: expose correct io hints

Set sensible I/O hints for striped DM devices in the topology
infrastructure added for 2.6.31 for userspace tools to
obtain via sysfs.

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 and implement this for dm-stripe.

Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>

diff --git a/drivers/md/dm-stripe.c b/drivers/md/dm-stripe.c
index 4e0e593..3e563d2 100644 (file)
--- a/drivers/md/dm-stripe.c
+++ b/drivers/md/dm-stripe.c
@@ -329,9 +329,19 @@ static int stripe_iterate_devices(struct dm_target *ti,
        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},
+       .version = {1, 3, 0},
        .module = THIS_MODULE,
        .ctr    = stripe_ctr,
        .dtr    = stripe_dtr,
@@ -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)

diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
index c90e662..1a6cb3c 100644 (file)
--- a/drivers/md/dm-table.c
+++ b/drivers/md/dm-table.c
@@ -1007,6 +1007,10 @@ int dm_calculate_queue_limits(struct dm_table *table,
                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.

diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h
index 655e772..df7607e 100644 (file)
--- a/include/linux/device-mapper.h
+++ b/include/linux/device-mapper.h
@@ -91,6 +91,9 @@ typedef int (*dm_iterate_devices_fn) (struct dm_target *ti,
                                      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;