From 0f5d690f7bf1b1a5354c61ac5b9d69a4329e218f Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Wed, 5 Apr 2017 19:21:04 +0200 Subject: [PATCH] dm io: discards don't take a payload Fix up do_region to not allocate a bio_vec for discards. We've got rid of the discard payload allocated by the caller years ago. Obviously this wasn't actually harmful given how long it's been there, but it's still good to avoid the pointless allocation. Signed-off-by: Christoph Hellwig Reviewed-by: Hannes Reinecke Signed-off-by: Jens Axboe --- drivers/md/dm-io.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c index 03940bf36f6c..b808cbe22678 100644 --- a/drivers/md/dm-io.c +++ b/drivers/md/dm-io.c @@ -328,11 +328,17 @@ static void do_region(int op, int op_flags, unsigned region, /* * Allocate a suitably sized-bio. */ - if ((op == REQ_OP_DISCARD) || (op == REQ_OP_WRITE_SAME)) + switch (op) { + case REQ_OP_DISCARD: + num_bvecs = 0; + break; + case REQ_OP_WRITE_SAME: num_bvecs = 1; - else + break; + default: num_bvecs = min_t(int, BIO_MAX_PAGES, dm_sector_div_up(remaining, (PAGE_SIZE >> SECTOR_SHIFT))); + } bio = bio_alloc_bioset(GFP_NOIO, num_bvecs, io->client->bios); bio->bi_iter.bi_sector = where->sector + (where->count - remaining);