[PATCH] dax: fix assertion in dax_iomap_rw()
Gao Xiang
hsiangkao at linux.alibaba.com
Thu Oct 2 19:56:37 AEST 2025
Hi Jan,
On 2025/10/2 16:13, Jan Kara wrote:
> dax_iomap_rw() asserts that inode lock is held when reading from it. The
> assert triggers on erofs as it indeed doesn't hold any locks in this
> case - naturally because there's nothing to race against when the
> filesystem is read-only. Check the locking only if the filesystem is
> actually writeable.
>
> Reported-by: syzbot+47680984f2d4969027ea at syzkaller.appspotmail.com
> Signed-off-by: Jan Kara <jack at suse.cz>
> ---
> fs/dax.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/fs/dax.c b/fs/dax.c
> index 20ecf652c129..187f8c325744 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -1752,7 +1752,7 @@ dax_iomap_rw(struct kiocb *iocb, struct iov_iter *iter,
> if (iov_iter_rw(iter) == WRITE) {
> lockdep_assert_held_write(&iomi.inode->i_rwsem);
> iomi.flags |= IOMAP_WRITE;
> - } else {
> + } else if (!IS_RDONLY(iomi.inode)) {
Thanks, Yuezheng also wrote a similiar patch
days ago (but it seems he didn't cc more related
people),
https://lore.kernel.org/r/20250930054256.2461984-2-Yuezhang.Mo@sony.com
both patches look good to me, thanks for the fix.
Thanks,
Gao Xiang
> lockdep_assert_held(&iomi.inode->i_rwsem);
> }
>
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