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/drivers/md/dm-snap.c b/drivers/md/dm-snap.c
index a228c20..6c0f3e3 100644
--- a/drivers/md/dm-snap.c
+++ b/drivers/md/dm-snap.c
@@ -691,7 +691,7 @@
* Return a minimum chunk size of all snapshots that have the specified origin.
* Return zero if the origin has no snapshots.
*/
-static sector_t __minimum_chunk_size(struct origin *o)
+static uint32_t __minimum_chunk_size(struct origin *o)
{
struct dm_snapshot *snap;
unsigned chunk_size = 0;
@@ -701,7 +701,7 @@
chunk_size = min_not_zero(chunk_size,
snap->store->chunk_size);
- return chunk_size;
+ return (uint32_t) chunk_size;
}
/*
@@ -1172,7 +1172,10 @@
ti->error = "Chunk size not set";
goto bad_read_metadata;
}
- ti->split_io = s->store->chunk_size;
+
+ r = dm_set_target_max_io_len(ti, s->store->chunk_size);
+ if (r)
+ goto bad_read_metadata;
return 0;
@@ -1239,7 +1242,7 @@
snap_dest->store->snap = snap_dest;
snap_src->store->snap = snap_src;
- snap_dest->ti->split_io = snap_dest->store->chunk_size;
+ snap_dest->ti->max_io_len = snap_dest->store->chunk_size;
snap_dest->valid = snap_src->valid;
/*
@@ -1817,9 +1820,9 @@
up_write(&s->lock);
}
-static sector_t get_origin_minimum_chunksize(struct block_device *bdev)
+static uint32_t get_origin_minimum_chunksize(struct block_device *bdev)
{
- sector_t min_chunksize;
+ uint32_t min_chunksize;
down_read(&_origins_lock);
min_chunksize = __minimum_chunk_size(__lookup_origin(bdev));
@@ -1838,9 +1841,9 @@
snapshot_resume(ti);
/*
- * snapshot-merge acts as an origin, so set ti->split_io
+ * snapshot-merge acts as an origin, so set ti->max_io_len
*/
- ti->split_io = get_origin_minimum_chunksize(s->origin->bdev);
+ ti->max_io_len = get_origin_minimum_chunksize(s->origin->bdev);
start_merge(s);
}
@@ -2073,12 +2076,12 @@
struct origin *o;
/*
- * The origin's __minimum_chunk_size() got stored in split_io
+ * The origin's __minimum_chunk_size() got stored in max_io_len
* by snapshot_merge_resume().
*/
down_read(&_origins_lock);
o = __lookup_origin(merging_snap->origin->bdev);
- for (n = 0; n < size; n += merging_snap->ti->split_io)
+ for (n = 0; n < size; n += merging_snap->ti->max_io_len)
if (__origin_write(&o->snapshots, sector + n, NULL) ==
DM_MAPIO_SUBMITTED)
must_wait = 1;
@@ -2138,14 +2141,14 @@
}
/*
- * Set the target "split_io" field to the minimum of all the snapshots'
+ * Set the target "max_io_len" field to the minimum of all the snapshots'
* chunk sizes.
*/
static void origin_resume(struct dm_target *ti)
{
struct dm_dev *dev = ti->private;
- ti->split_io = get_origin_minimum_chunksize(dev->bdev);
+ ti->max_io_len = get_origin_minimum_chunksize(dev->bdev);
}
static int origin_status(struct dm_target *ti, status_type_t type, char *result,