block/bio: Do not zero user pages

Keith Busch · axboe · commit f55adad601c6 · 2018-12-10T13:37:20.000-07:00
We don't need to zero fill the bio if not using kernel allocated pages. Fixes: f3587d7 ("block: Clear kernel memory before copying to user") # v4.20-rc2 Reported-by: Todd Aiken <taiken@mvtech.ca> Cc: Laurence Oberman <loberman@redhat.com> Cc: stable@vger.kernel.org Cc: Bart Van Assche <bvanassche@acm.org> Tested-by: Laurence Oberman <loberman@redhat.com> Signed-off-by: Keith Busch <keith.busch@intel.com> Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/block/bio.c b/block/bio.c
@@ -1261,7 +1261,8 @@ struct bio *bio_copy_user_iov(struct request_queue *q,
 		if (ret)
 			goto cleanup;
 	} else {
-		zero_fill_bio(bio);
+		if (bmd->is_our_pages)
+			zero_fill_bio(bio);
 		iov_iter_advance(iter, bio->bi_iter.bi_size);
 	}
 

Original file line number	Diff line number	Diff line change
`@@ -1261,7 +1261,8 @@ struct bio bio_copy_user_iov(struct request_queue q,`
`1261`	`1261`	`if (ret)`
`1262`	`1262`	`goto cleanup;`
`1263`	`1263`	`} else {`
`1264`		`- zero_fill_bio(bio);`
	`1264`	`+ if (bmd->is_our_pages)`
	`1265`	`+ zero_fill_bio(bio);`
`1265`	`1266`	`iov_iter_advance(iter, bio->bi_iter.bi_size);`
`1266`	`1267`	`}`
`1267`	`1268`