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

Christoph Hellwig
2021-06-15T14:44:58Z

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@lst.de>
Tested-by: Mark Wunderlich <mark.wunderlich@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);