[PATCH v2 10/51] dm: limit the max bio size as BIO_MAX_PAGES * PAGE_SIZE

From: Ming Lei
Date: Mon Jun 26 2017 - 08:14:52 EST


For BIO based DM, some targets aren't ready for dealing with
bigger incoming bio than 1Mbyte, such as crypt target.

Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
Cc:dm-devel@xxxxxxxxxx
Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
---
drivers/md/dm.c | 11 ++++++++++-
1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index 96bd13e581cd..49583c623cdd 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -921,7 +921,16 @@ int dm_set_target_max_io_len(struct dm_target *ti, sector_t len)
return -EINVAL;
}

- ti->max_io_len = (uint32_t) len;
+ /*
+ * BIO based queue uses its own splitting. When multipage bvecs
+ * is switched on, size of the incoming bio may be too big to
+ * be handled in some targets, such as crypt.
+ *
+ * When these targets are ready for the big bio, we can remove
+ * the limit.
+ */
+ ti->max_io_len = min_t(uint32_t, len,
+ (BIO_MAX_PAGES * PAGE_SIZE));

return 0;
}
--
2.9.4