[PATCH 03/16] iomap: don't try to poll multi-bio I/Os in __iomap_dio_rw

[Christoph Hellwig]

If an iocb is split into multiple bios we can't poll for both.  So don't
bother to even try to poll in that case.

Signed-off-by: Christoph Hellwig <hch at lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich at intel.com>
---
 fs/iomap/direct-io.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/fs/iomap/direct-io.c b/fs/iomap/direct-io.c
index 9398b8c31323..d5637f467109 100644
--- a/fs/iomap/direct-io.c
+++ b/fs/iomap/direct-io.c
@@ -282,6 +282,13 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 	if (!iov_iter_count(dio->submit.iter))
 		goto out;
 
+	/*
+	 * We can only poll for single bio I/Os.
+	 */
+	if (need_zeroout ||
+	    ((dio->flags & IOMAP_DIO_WRITE) && pos >= i_size_read(inode)))
+		dio->iocb->ki_flags &= ~IOCB_HIPRI;
+
 	if (need_zeroout) {
 		/* zero out from the start of the block to the write offset */
 		pad = pos & (fs_block_size - 1);
@@ -339,6 +346,11 @@ iomap_dio_bio_actor(struct inode *inode, loff_t pos, loff_t length,
 
 		nr_pages = bio_iov_vecs_to_alloc(dio->submit.iter,
 						 BIO_MAX_VECS);
+		/*
+		 * We can only poll for single bio I/Os.
+		 */
+		if (nr_pages)
+			dio->iocb->ki_flags &= ~IOCB_HIPRI;
 		iomap_dio_submit_bio(dio, iomap, bio, pos);
 		pos += n;
 	} while (nr_pages);
@@ -579,6 +591,11 @@ __iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter,
 			iov_iter_revert(iter, pos - dio->i_size);
 			break;
 		}
+
+		/*
+		 * We can only poll for single bio I/Os.
+		 */
+		iocb->ki_flags &= ~IOCB_HIPRI;
 	} while ((count = iov_iter_count(iter)) > 0);
 	blk_finish_plug(&plug);
 
-- 
2.30.2