@@ -823,5 +823,19 @@ static inline int bio_integrity_add_page(struct bio *bio, struct page *page,
#endif /* CONFIG_BLK_DEV_INTEGRITY */
+/*
+ * Mark a bio as polled. Note that for async polled IO, the caller must
+ * expect -EWOULDBLOCK if we cannot allocate a request (or other resources).
+ * We cannot block waiting for requests on polled IO, as those completions
+ * must be found by the caller. This is different than IRQ driven IO, where
+ * it's safe to wait for IO to complete.
+ */
+static inline void bio_set_polled(struct bio *bio, struct kiocb *kiocb)
+{
+ bio->bi_opf |= REQ_HIPRI;
+ if (!is_sync_kiocb(kiocb))
+ bio->bi_opf |= REQ_NOWAIT;
+}
+
#endif /* CONFIG_BLOCK */
#endif /* __LINUX_BIO_H */
For the upcoming async polled IO, we can't sleep allocating requests. If we do, then we introduce a deadlock where the submitter already has async polled IO in-flight, but can't wait for them to complete since polled requests must be active found and reaped. Signed-off-by: Jens Axboe <axboe@kernel.dk> --- include/linux/bio.h | 14 ++++++++++++++ 1 file changed, 14 insertions(+)