On Tue, Dec 27 2016 at 10:56am -0500, Ming Lei <tom.leim...@gmail.com> wrote:
> For BIO based DM, some targets aren't ready for dealing with > bigger incoming bio than 1Mbyte, such as crypt target. > > Signed-off-by: Ming Lei <tom.leim...@gmail.com> > --- > 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 3086da5664f3..6139bf7623f7 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. > + * > + * 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; > } > -- > 2.7.4 dm_set_target_max_io_len() is already meant to be called by the .ctr hook for each DM target. So why not just have the dm-crypt target (and other targets if needed) pass your reduced $len? That way only targets that need to be fixed (e.g. dm-crypt) impose this limit.
