From:   George Kennedy <george.kennedy@oracle.com>
To:     gregkh@linuxfoundation.org, axboe@kernel.dk, asml.silence@gmail.com
Cc:     george.kennedy@oracle.com, linux-block@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] Revert "block: avoid extra iter advance with async iocb"
Date:   Tue,  7 Dec 2021 10:51:41 -0500
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This reverts commit 1bb6b81029456f4e2e6727c5167f43bdfc34bee5.

Revert this commit in order to be able to revert
commit 54a88eb838d3 ("block: add single bio async direct IO helper")

Reported-by: syzkaller <syzkaller@googlegroups.com>
Signed-off-by: George Kennedy <george.kennedy@oracle.com>
---
 block/bio.c         |  2 +-
 block/fops.c        | 20 +++++---------------
 include/linux/bio.h |  1 -
 3 files changed, 6 insertions(+), 17 deletions(-)

diff --git a/block/bio.c b/block/bio.c
index 15ab0d6..ead1f8a 100644
--- a/block/bio.c
+++ b/block/bio.c
@@ -1046,7 +1046,7 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty)
 }
 EXPORT_SYMBOL_GPL(__bio_release_pages);
 
-void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter)
+static void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter)
 {
 	size_t size = iov_iter_count(iter);
 
diff --git a/block/fops.c b/block/fops.c
index ad732a3..e73167b 100644
--- a/block/fops.c
+++ b/block/fops.c
@@ -329,21 +329,11 @@ static ssize_t __blkdev_direct_IO_async(struct kiocb *iocb,
 	bio->bi_end_io = blkdev_bio_end_io_async;
 	bio->bi_ioprio = iocb->ki_ioprio;
 
-	if (iov_iter_is_bvec(iter)) {
-		/*
-		 * Users don't rely on the iterator being in any particular
-		 * state for async I/O returning -EIOCBQUEUED, hence we can
-		 * avoid expensive iov_iter_advance(). Bypass
-		 * bio_iov_iter_get_pages() and set the bvec directly.
-		 */
-		bio_iov_bvec_set(bio, iter);
-	} else {
-		ret = bio_iov_iter_get_pages(bio, iter);
-		if (unlikely(ret)) {
-			bio->bi_status = BLK_STS_IOERR;
-			bio_endio(bio);
-			return ret;
-		}
+	ret = bio_iov_iter_get_pages(bio, iter);
+	if (unlikely(ret)) {
+		bio->bi_status = BLK_STS_IOERR;
+		bio_endio(bio);
+		return ret;
 	}
 	dio->size = bio->bi_iter.bi_size;
 
diff --git a/include/linux/bio.h b/include/linux/bio.h
index fe6bdfb..c88700d 100644
--- a/include/linux/bio.h
+++ b/include/linux/bio.h
@@ -417,7 +417,6 @@ int bio_add_zone_append_page(struct bio *bio, struct page *page,
 void __bio_add_page(struct bio *bio, struct page *page,
 		unsigned int len, unsigned int off);
 int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter);
-void bio_iov_bvec_set(struct bio *bio, struct iov_iter *iter);
 void __bio_release_pages(struct bio *bio, bool mark_dirty);
 extern void bio_set_pages_dirty(struct bio *bio);
 extern void bio_check_pages_dirty(struct bio *bio);
-- 
1.8.3.1