linux-ext4 - Re: [syzbot] [ext4?] WARNING in ext4_file_write

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Date:   Fri, 4 Aug 2023 10:15:07 -0400
From:   Brian Foster <bfoster@...hat.com>
To:     syzbot <syzbot+5050ad0fb47527b1808a@...kaller.appspotmail.com>
Cc:     syzkaller-bugs@...glegroups.com, linux-ext4@...r.kernel.org
Subject: Re: [syzbot] [ext4?] WARNING in ext4_file_write_iter

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/fs/ext4/file.c b/fs/ext4/file.c
index c457c8517f0f..5642a3466c5d 100644
--- a/fs/ext4/file.c
+++ b/fs/ext4/file.c
@@ -504,9 +504,7 @@ static ssize_t ext4_dio_write_checks(struct kiocb *iocb, struct iov_iter *from,
 	 * non-overwrite or extending, so drain all outstanding dio and set the
 	 * force wait dio flag.
 	 */
-	if (*ilock_shared && unaligned_io) {
-		*dio_flags = IOMAP_DIO_OVERWRITE_ONLY;
-	} else if (!*ilock_shared && (unaligned_io || *extend)) {
+	if (!*ilock_shared && (unaligned_io || *extend)) {
 		if (iocb->ki_flags & IOCB_NOWAIT) {
 			ret = -EAGAIN;
 			goto out;
@@ -608,7 +606,6 @@ static ssize_t ext4_dio_write_iter(struct kiocb *iocb, struct iov_iter *from)
 		iomap_ops = &ext4_iomap_overwrite_ops;
 	ret = iomap_dio_rw(iocb, from, iomap_ops, &ext4_dio_write_ops,
 			   dio_flags, NULL, 0);
-	WARN_ON_ONCE(ret == -EAGAIN && !(iocb->ki_flags & IOCB_NOWAIT));
 	if (ret == -ENOTBLK)
 		ret = 0;