On 8/14/18 10:22 AM, Linus Torvalds wrote: > On Tue, Aug 14, 2018 at 8:24 AM Ilya Dryomov <idryo...@gmail.com> wrote: >> >> Looks like it's coming from that fsync(): >> >> sys_fsync >> do_fsync >> vfs_fsync_range >> blkdev_fsync >> blkdev_issue_flush >> >> I think we need to teach blkdev_issue_flush() to bail out if the bdev >> is read-only, similar to blkdev_issue_discard(), _write_zeroes(), etc. >> The question is which error code to use. blkdev_fsync() already skips >> over EOPNOTSUPP, so it is a (no-so-good) option. Other blkdev_issue_ >> functions return EPERM. > > Oh, just make issue_flush() return EROFS for a read-only device. > > Or maybe we should even just consider the flush to be a read operation? > > But I guess the error code gets percolated all the way to user space? > The safest option might just be to return 0.
We probably just want to special case a flush for this check. In other situations, like resource allocation and issue, we'd want to consider it a write. -- Jens Axboe
