Commit 270a1c91 authored Aug 12, 2021 by Jens Axboe

block: provide bio_clear_hipri() helper



Any case that turns off REQ_HIPRI must also clear BIO_PERCPU_CACHE,
as non-polled IO may complete through hard/soft IRQ and hence isn't
safe for our polled bio alloc cache.

Provide a helper that does just that, and use it in the merging code as
well if we split a bio and turn off polling.

Fixes: be863b9e ("block: clear BIO_PERCPU_CACHE flag if polling isn't supported")
Reported-by: Keith Busch <kbusch@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

parent 01cfa28a

block/blk-core.c

+2 −5

Original line number	Diff line number	Diff line
		@@ -832,11 +832,8 @@ static noinline_for_stack bool submit_bio_checks(struct bio *bio)
		}
		}

		if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags)) {
		/* can't support alloc cache if we turn off polling */
		bio_clear_flag(bio, BIO_PERCPU_CACHE);
		bio->bi_opf &= ~REQ_HIPRI;
		}
		if (!test_bit(QUEUE_FLAG_POLL, &q->queue_flags))
		bio_clear_hipri(bio);

		switch (bio_op(bio)) {
		case REQ_OP_DISCARD:

block/blk-merge.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -285,7 +285,7 @@ static struct bio blk_bio_segment_split(struct request_queue q,
		* iopoll in direct IO routine. Given performance gain of iopoll for
		* big IO can be trival, disable iopoll when split needed.
		*/
		bio->bi_opf &= ~REQ_HIPRI;
		bio_clear_hipri(bio);

		return bio_split(bio, sectors, GFP_NOIO, bs);
		}

block/blk.h

+7 −0

Original line number	Diff line number	Diff line
		@@ -364,4 +364,11 @@ extern struct device_attribute dev_attr_events;
		extern struct device_attribute dev_attr_events_async;
		extern struct device_attribute dev_attr_events_poll_msecs;

		static inline void bio_clear_hipri(struct bio *bio)
		{
		/* can't support alloc cache if we turn off polling */
		bio_clear_flag(bio, BIO_PERCPU_CACHE);
		bio->bi_opf &= ~REQ_HIPRI;
		}

		#endif /* BLK_INTERNAL_H */