On Thu, Dec 07, 2017 at 01:30:03PM +0800, Matthew Wilcox wrote: > On Thu, Dec 07, 2017 at 10:46:22AM +0800, 穆阿浩(姜弋) wrote: > > This issue is found when creating /dev/sdtest with flags (O_CREAT | > > O_DIRECT). The file still can be retrieved even after system reports > > failure (-EINVAL) for it. Reporting error on creating the file is > > correct behaviour because either devtmpfs or tmpfs doesn't support > > O_DIRECT for regular file. However, it's incorrect that the file is > > still existing. The cause is the newly allocated dentry and inode > > aren't released on failure in do_last(). > > Previously reported: > > https://www.spinics.net/lists/linux-fsdevel/msg89317.html > https://www.spinics.net/lists/linux-fsdevel/msg113680.html > http://lkml.iu.edu/hypermail/linux/kernel/1609.0/04556.html > Thanks, Matthew. I start to realize it's a long-standing issue :) > > +++ b/fs/namei.c > > @@ -3382,6 +3382,8 @@ static int do_last(struct nameidata *nd, > > *opened |= FILE_OPENED; > > opened: > > error = open_check_o_direct(file); > > + if (error && (*opened & FILE_OPENED)) > > + dput(path.dentry); > > if (!error) > > error = ima_file_check(file, op->acc_mode, *opened); > > if (!error && will_truncate) > > Umm ... I think it's too late. This will work well enough for in-memory > filesystems, but if you have a real filesystem, there's no call back to > the filesystem to remove the directory entry, right? Yeah, it's late to roll back on real filesystem like ext4. As I replied to Al Viro in another thread, the doable fix would be pass O_DIRECT down to struct inode_operations::create() and the specific filesystem rejects creating inode if O_DIRECT isn't supported there. Cheers, Gavin
