[PATCH 29/60] dm: limit the max bio size as BIO_SP_MAX_SECTORS << SECTOR_SHIFT

From: Ming Lei
Date: Sat Oct 29 2016 - 04:27:57 EST


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

Signed-off-by: Ming Lei <tom.leiming@xxxxxxxxx>
---
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 ef7bf1dd6900..ce454c6c1a4e 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -899,7 +899,16 @@ 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 and log write.
+ *
+ * When these targets are ready for the big bio, we can remove
+ * the limit.
+ */
+ ti->max_io_len = min_t(uint32_t, len,
+ BIO_SP_MAX_SECTORS << SECTOR_SHIFT);

return 0;
}
--
2.7.4