On Tue, Oct 04, 2016 at 11:00:41AM +0200, Jan Kara wrote:
> Hi!
>
> On Mon 03-10-16 16:30:55, Tony Lindgren wrote:
> > I'm seeing a repeatable oops with Linux next while running
> > update-initramfs, see below. I tried reverting commit 59aa5a3aeead
> > ("fscrypto: make filename crypto functions return 0 on success")
> > as that's the only commit changing ext4_htree_store_dirent, but
> > that did not help.
> >
> > Anybody else seeing something like this?
>
> Never seen this but I suspect it is a fallout from Al's directory locking
> changes. In particular ext4_htree_fill_tree() builds rb-tree of found
> directory entries in file->private_data (and generally modifies the
> structure stored there) but after Al's changes we don't have exclusive
> access to struct file if I'm right so if two processes end up calling
> getdents() for the same 'struct file' we are doomed.
RTFS. We sure as hell *do* have exclusive access to struct file. See
/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
if (S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))
f->f_mode |= FMODE_ATOMIC_POS;
in do_dentry_open() as well as
if (file && (file->f_mode & FMODE_ATOMIC_POS)) {
if (file_count(file) > 1) {
v |= FDPUT_POS_UNLOCK;
mutex_lock(&file->f_pos_lock);
}
}
in __fdget_pos() and
f = fdget_pos(fd);
if (!f.file)
return -EBADF;
in getdents(2).
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