Re: [PATCH v4 2/2] ceph: add ceph specific member support for file_lock

[Xiubo Li]

On 14/12/2022 02:05, Ilya Dryomov wrote:
> On Tue, Dec 13, 2022 at 1:11 PM <xiubli@xxxxxxxxxx> wrote:
> > From: Xiubo Li <xiubli@xxxxxxxxxx>
> >
> > When ceph releasing the file_lock it will try to get the inode pointer
> > from the fl->fl_file, which the memory could already be released by
> > another thread in filp_close(). Because in VFS layer the fl->fl_file
> > doesn't increase the file's reference counter.
> >
> > Will switch to use ceph dedicate lock info to track the inode.
> >
> > And in ceph_fl_release_lock() we should skip all the operations if
> > the fl->fl_u.ceph_fl.fl_inode is not set, which should come from
> > the request file_lock. And we will set fl->fl_u.ceph_fl.fl_inode when
> > inserting it to the inode lock list, which is when copying the lock.
> >
> > Cc: stable@xxxxxxxxxxxxxxx
> > Cc: Jeff Layton <jlayton@xxxxxxxxxx>
> > URL: https://tracker.ceph.com/issues/57986
> > Signed-off-by: Xiubo Li <xiubli@xxxxxxxxxx>
> > ---
> >   fs/ceph/locks.c    | 20 ++++++++++++++++++--
> >   include/linux/fs.h |  3 +++
> >   2 files changed, 21 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/ceph/locks.c b/fs/ceph/locks.c
> > index b191426bf880..cf78608a3f9a 100644
> > --- a/fs/ceph/locks.c
> > +++ b/fs/ceph/locks.c
> > @@ -34,18 +34,34 @@ static void ceph_fl_copy_lock(struct file_lock *dst, struct file_lock *src)
> >   {
> >          struct inode *inode = file_inode(dst->fl_file);
> >          atomic_inc(&ceph_inode(inode)->i_filelock_ref);
> > +       dst->fl_u.ceph.fl_inode = igrab(inode);
> >   }
> >
> > +/*
> > + * Do not use the 'fl->fl_file' in release function, which
> > + * is possibly already released by another thread.
> > + */
> >   static void ceph_fl_release_lock(struct file_lock *fl)
> >   {
> > -       struct inode *inode = file_inode(fl->fl_file);
> > -       struct ceph_inode_info *ci = ceph_inode(inode);
> > +       struct inode *inode = fl->fl_u.ceph.fl_inode;
> > +       struct ceph_inode_info *ci;
> > +
> > +       /*
> > +        * If inode is NULL it should be a request file_lock,
> > +        * nothing we can do.
> > +        */
> > +       if (!inode)
> > +               return;
> > +
> > +       ci = ceph_inode(inode);
> >          if (atomic_dec_and_test(&ci->i_filelock_ref)) {
> >                  /* clear error when all locks are released */
> >                  spin_lock(&ci->i_ceph_lock);
> >                  ci->i_ceph_flags &= ~CEPH_I_ERROR_FILELOCK;
> >                  spin_unlock(&ci->i_ceph_lock);
> >          }
> > +       fl->fl_u.ceph.fl_inode = NULL;
> > +       iput(inode);
> >   }
> >
> >   static const struct file_lock_operations ceph_fl_lock_ops = {
> > diff --git a/include/linux/fs.h b/include/linux/fs.h
> > index 7b52fdfb6da0..6106374f5257 100644
> > --- a/include/linux/fs.h
> > +++ b/include/linux/fs.h
> > @@ -1119,6 +1119,9 @@ struct file_lock {
> >                          int state;              /* state of grant or error if -ve */
> >                          unsigned int    debug_id;
> >                  } afs;
> > +               struct {
> > +                       struct inode *fl_inode;
> Hi Xiubo,
>
> Nit: I think it could be just "inode", without the prefix which is
> already present in the union field name.

Okay, I can fix this in the next version.

Thanks.

- Xiubo


> Thanks,
>
>                  Ilya