dm: factor out max_io_len_target_boundary
Split max_io_len_target_boundary out of max_io_len so that the discard
support can make use of it without duplicating max_io_len code.
Avoiding max_io_len's split_io logic enables DM's discard support to
submit the entire discard request to a target. But discards must still
be split on target boundaries.
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 3dd846e..561313a 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -1030,17 +1030,27 @@
dm_complete_request(clone, error);
}
-static sector_t max_io_len(struct mapped_device *md,
- sector_t sector, struct dm_target *ti)
+/*
+ * Return maximum size of I/O possible at the supplied sector up to the current
+ * target boundary.
+ */
+static sector_t max_io_len_target_boundary(sector_t sector, struct dm_target *ti)
{
- sector_t offset = sector - ti->begin;
- sector_t len = ti->len - offset;
+ sector_t target_offset = dm_target_offset(ti, sector);
+
+ return ti->len - target_offset;
+}
+
+static sector_t max_io_len(sector_t sector, struct dm_target *ti)
+{
+ sector_t len = max_io_len_target_boundary(sector, ti);
/*
* Does the target need to split even further ?
*/
if (ti->split_io) {
sector_t boundary;
+ sector_t offset = dm_target_offset(ti, sector);
boundary = ((offset + ti->split_io) & ~(ti->split_io - 1))
- offset;
if (len > boundary)
@@ -1258,7 +1268,7 @@
if (!ti->num_discard_requests)
return -EOPNOTSUPP;
- max = max_io_len(ci->md, ci->sector, ti);
+ max = max_io_len(ci->sector, ti);
if (ci->sector_count > max)
/*
@@ -1290,7 +1300,7 @@
if (!dm_target_is_valid(ti))
return -EIO;
- max = max_io_len(ci->md, ci->sector, ti);
+ max = max_io_len(ci->sector, ti);
if (ci->sector_count <= max) {
/*
@@ -1341,7 +1351,7 @@
if (!dm_target_is_valid(ti))
return -EIO;
- max = max_io_len(ci->md, ci->sector, ti);
+ max = max_io_len(ci->sector, ti);
}
len = min(remaining, max);
@@ -1428,7 +1438,7 @@
/*
* Find maximum amount of I/O that won't need splitting
*/
- max_sectors = min(max_io_len(md, bvm->bi_sector, ti),
+ max_sectors = min(max_io_len(bvm->bi_sector, ti),
(sector_t) BIO_MAX_SECTORS);
max_size = (max_sectors << SECTOR_SHIFT) - bvm->bi_size;
if (max_size < 0)