block: mark bio_wouldblock_error() bio with BIO_QUIET

We really don't care about triggering buffer errors for this condition.
This avoids a spew of:

Buffer I/O error on dev sdc, logical block 785929, async page read
Buffer I/O error on dev sdc, logical block 759095, async page read
Buffer I/O error on dev sdc, logical block 766922, async page read
Buffer I/O error on dev sdc, logical block 17659, async page read
Buffer I/O error on dev sdc, logical block 637571, async page read
Buffer I/O error on dev sdc, logical block 39241, async page read
Buffer I/O error on dev sdc, logical block 397241, async page read
Buffer I/O error on dev sdc, logical block 763992, async page read

from -EAGAIN conditions on request allocation for async reads.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

include/linux/bio.h

@@ -417,6 +417,7 @@ static inline void bio_io_error(struct bio *bio)
 
 static inline void bio_wouldblock_error(struct bio *bio)
 {
+	bio_set_flag(bio, BIO_QUIET);
 	bio->bi_status = BLK_STS_AGAIN;
 	bio_endio(bio);
 }