On Thu, 2020-01-09 at 10:05 +0800, Xiubo Li wrote:
> On 2020/1/6 23:35, Jeff Layton wrote:
> > Currently, we just assume that it will stick around by virtue of the
> > submitter's reference, but later patches will allow the syscall to
> > return early and we can't rely on that reference at that point.
> >
> > Take an extra reference to the inode when setting r_parent and release
> > it when releasing the request.
> >
> > Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> > ---
> > fs/ceph/mds_client.c | 8 ++++++--
> > 1 file changed, 6 insertions(+), 2 deletions(-)
> >
> > diff --git a/fs/ceph/mds_client.c b/fs/ceph/mds_client.c
> > index 94cce2ab92c4..b7122f682678 100644
> > --- a/fs/ceph/mds_client.c
> > +++ b/fs/ceph/mds_client.c
> > @@ -708,8 +708,10 @@ void ceph_mdsc_release_request(struct kref *kref)
> > /* avoid calling iput_final() in mds dispatch threads */
> > ceph_async_iput(req->r_inode);
> > }
> > - if (req->r_parent)
> > + if (req->r_parent) {
> > ceph_put_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
> > + ceph_async_iput(req->r_parent);
> > + }
> > ceph_async_iput(req->r_target_inode);
> > if (req->r_dentry)
> > dput(req->r_dentry);
> > @@ -2706,8 +2708,10 @@ int ceph_mdsc_submit_request(struct ceph_mds_client *mdsc, struct inode *dir,
> > /* take CAP_PIN refs for r_inode, r_parent, r_old_dentry */
> > if (req->r_inode)
> > ceph_get_cap_refs(ceph_inode(req->r_inode), CEPH_CAP_PIN);
> > - if (req->r_parent)
> > + if (req->r_parent) {
> > ceph_get_cap_refs(ceph_inode(req->r_parent), CEPH_CAP_PIN);
> > + ihold(req->r_parent);
> > + }
>
> This might also fix another issue when the mdsc request is timedout and
> returns to the vfs, then the r_parent maybe released in vfs. And then if
> we reference it again in mdsc handle_reply() -->
> ceph_mdsc_release_request(), some unknown issues may happen later ??
>
AIUI, when a timeout occurs, the req is unhashed such that handle_reply
can't find it. So, I doubt this affects that one way or another.
> > if (req->r_old_dentry_dir)
> > ceph_get_cap_refs(ceph_inode(req->r_old_dentry_dir),
> > CEPH_CAP_PIN);
>
>
--
Jeff Layton <jlayton@xxxxxxxxxx>
