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In-Reply-To: <28572446-B32A-461F-A9C1-E60F79B985D3@oracle.com>
From:   Olga Kornievskaia <aglo@umich.edu>
Date:   Thu, 5 Jan 2023 11:10:14 -0500
Message-ID: <CAN-5tyEL1FvvCMgg=NWrHcAvLdXFKZQ_p1T8gRhH9hUoD3jPhA@mail.gmail.com>
Subject: Re: [PATCH v2 1/1] NFSD: enhance inter-server copy cleanup
To:     Chuck Lever III <chuck.lever@oracle.com>
Cc:     Dai Ngo <dai.ngo@oracle.com>,
        "jlayton@kernel.org" <jlayton@kernel.org>,
        Olga Kornievskaia <kolga@netapp.com>,
        Linux NFS Mailing List <linux-nfs@vger.kernel.org>
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On Tue, Jan 3, 2023 at 11:14 AM Chuck Lever III <chuck.lever@oracle.com> wrote:
>
>
>
> > On Dec 18, 2022, at 7:55 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
> >
> > Currently nfsd4_setup_inter_ssc returns the vfsmount of the source
> > server's export when the mount completes. After the copy is done
> > nfsd4_cleanup_inter_ssc is called with the vfsmount of the source
> > server and it searches nfsd_ssc_mount_list for a matching entry
> > to do the clean up.
> >
> > The problems with this approach are (1) the need to search the
> > nfsd_ssc_mount_list and (2) the code has to handle the case where
> > the matching entry is not found which looks ugly.
> >
> > The enhancement is instead of nfsd4_setup_inter_ssc returning the
> > vfsmount, it returns the nfsd4_ssc_umount_item which has the
> > vfsmount embedded in it. When nfsd4_cleanup_inter_ssc is called
> > it's passed with the nfsd4_ssc_umount_item directly to do the
> > clean up so no searching is needed and there is no need to handle
> > the 'not found' case.
> >
> > Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> > ---
> > V2: fix compile error when CONFIG_NFSD_V4_2_INTER_SSC not defined.
> >    Reported by kernel test robot.
>
> Hello Dai - I've looked at this, nothing to comment on so far. I
> plan to go over it again sometime this week.
>
> I'd like to hear from others before applying it.

I have looked at it and logically it seems ok to me. I have tested it
(sorta. i'm rarely able to finish). But I keep running into the other
problem (nfsd4_state_shrinker_count soft lockup that's been already
reported). I find it interesting that only my destination server hits
the problem (but not the source server). I don't believe this patch
has anything to do with this problem, but I found it interesting that
ssc testing seems to trigger it 100%.


> > fs/nfsd/nfs4proc.c      | 94 +++++++++++++++++++------------------------------
> > fs/nfsd/xdr4.h          |  2 +-
> > include/linux/nfs_ssc.h |  2 +-
> > 3 files changed, 38 insertions(+), 60 deletions(-)
> >
> > diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
> > index b79ee65ae016..6515b00520bc 100644
> > --- a/fs/nfsd/nfs4proc.c
> > +++ b/fs/nfsd/nfs4proc.c
> > @@ -1295,15 +1295,15 @@ extern void nfs_sb_deactive(struct super_block *sb);
> >  * setup a work entry in the ssc delayed unmount list.
> >  */
> > static __be32 nfsd4_ssc_setup_dul(struct nfsd_net *nn, char *ipaddr,
> > -             struct nfsd4_ssc_umount_item **retwork, struct vfsmount **ss_mnt)
> > +             struct nfsd4_ssc_umount_item **nsui)
> > {
> >       struct nfsd4_ssc_umount_item *ni = NULL;
> >       struct nfsd4_ssc_umount_item *work = NULL;
> >       struct nfsd4_ssc_umount_item *tmp;
> >       DEFINE_WAIT(wait);
> > +     __be32 status = 0;
> >
> > -     *ss_mnt = NULL;
> > -     *retwork = NULL;
> > +     *nsui = NULL;
> >       work = kzalloc(sizeof(*work), GFP_KERNEL);
> > try_again:
> >       spin_lock(&nn->nfsd_ssc_lock);
> > @@ -1326,12 +1326,12 @@ static __be32 nfsd4_ssc_setup_dul(struct nfsd_net *nn, char *ipaddr,
> >                       finish_wait(&nn->nfsd_ssc_waitq, &wait);
> >                       goto try_again;
> >               }
> > -             *ss_mnt = ni->nsui_vfsmount;
> > +             *nsui = ni;
> >               refcount_inc(&ni->nsui_refcnt);
> >               spin_unlock(&nn->nfsd_ssc_lock);
> >               kfree(work);
> >
> > -             /* return vfsmount in ss_mnt */
> > +             /* return vfsmount in (*nsui)->nsui_vfsmount */
> >               return 0;
> >       }
> >       if (work) {
> > @@ -1339,10 +1339,11 @@ static __be32 nfsd4_ssc_setup_dul(struct nfsd_net *nn, char *ipaddr,
> >               refcount_set(&work->nsui_refcnt, 2);
> >               work->nsui_busy = true;
> >               list_add_tail(&work->nsui_list, &nn->nfsd_ssc_mount_list);
> > -             *retwork = work;
> > -     }
> > +             *nsui = work;
> > +     } else
> > +             status = nfserr_resource;
> >       spin_unlock(&nn->nfsd_ssc_lock);
> > -     return 0;
> > +     return status;
> > }
> >
> > static void nfsd4_ssc_update_dul_work(struct nfsd_net *nn,
> > @@ -1371,7 +1372,7 @@ static void nfsd4_ssc_cancel_dul_work(struct nfsd_net *nn,
> >  */
> > static __be32
> > nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> > -                    struct vfsmount **mount)
> > +                     struct nfsd4_ssc_umount_item **nsui)
> > {
> >       struct file_system_type *type;
> >       struct vfsmount *ss_mnt;
> > @@ -1382,7 +1383,6 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> >       char *ipaddr, *dev_name, *raw_data;
> >       int len, raw_len;
> >       __be32 status = nfserr_inval;
> > -     struct nfsd4_ssc_umount_item *work = NULL;
> >       struct nfsd_net *nn = net_generic(SVC_NET(rqstp), nfsd_net_id);
> >
> >       naddr = &nss->u.nl4_addr;
> > @@ -1390,6 +1390,7 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> >                                        naddr->addr_len,
> >                                        (struct sockaddr *)&tmp_addr,
> >                                        sizeof(tmp_addr));
> > +     *nsui = NULL;
> >       if (tmp_addrlen == 0)
> >               goto out_err;
> >
> > @@ -1432,10 +1433,10 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> >               goto out_free_rawdata;
> >       snprintf(dev_name, len + 5, "%s%s%s:/", startsep, ipaddr, endsep);
> >
> > -     status = nfsd4_ssc_setup_dul(nn, ipaddr, &work, &ss_mnt);
> > +     status = nfsd4_ssc_setup_dul(nn, ipaddr, nsui);
> >       if (status)
> >               goto out_free_devname;
> > -     if (ss_mnt)
> > +     if ((*nsui)->nsui_vfsmount)
> >               goto out_done;
> >
> >       /* Use an 'internal' mount: SB_KERNMOUNT -> MNT_INTERNAL */
> > @@ -1443,15 +1444,12 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> >       module_put(type->owner);
> >       if (IS_ERR(ss_mnt)) {
> >               status = nfserr_nodev;
> > -             if (work)
> > -                     nfsd4_ssc_cancel_dul_work(nn, work);
> > +             nfsd4_ssc_cancel_dul_work(nn, *nsui);
> >               goto out_free_devname;
> >       }
> > -     if (work)
> > -             nfsd4_ssc_update_dul_work(nn, work, ss_mnt);
> > +     nfsd4_ssc_update_dul_work(nn, *nsui, ss_mnt);
> > out_done:
> >       status = 0;
> > -     *mount = ss_mnt;
> >
> > out_free_devname:
> >       kfree(dev_name);
> > @@ -1474,8 +1472,7 @@ nfsd4_interssc_connect(struct nl4_server *nss, struct svc_rqst *rqstp,
> >  */
> > static __be32
> > nfsd4_setup_inter_ssc(struct svc_rqst *rqstp,
> > -                   struct nfsd4_compound_state *cstate,
> > -                   struct nfsd4_copy *copy, struct vfsmount **mount)
> > +             struct nfsd4_compound_state *cstate, struct nfsd4_copy *copy)
> > {
> >       struct svc_fh *s_fh = NULL;
> >       stateid_t *s_stid = &copy->cp_src_stateid;
> > @@ -1488,7 +1485,8 @@ nfsd4_setup_inter_ssc(struct svc_rqst *rqstp,
> >       if (status)
> >               goto out;
> >
> > -     status = nfsd4_interssc_connect(copy->cp_src, rqstp, mount);
> > +     status = nfsd4_interssc_connect(copy->cp_src, rqstp,
> > +                             &copy->ss_nsui);
> >       if (status)
> >               goto out;
> >
> > @@ -1506,61 +1504,42 @@ nfsd4_setup_inter_ssc(struct svc_rqst *rqstp,
> > }
> >
> > static void
> > -nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
> > +nfsd4_cleanup_inter_ssc(struct nfsd4_ssc_umount_item *ni, struct file *filp,
> >                       struct nfsd_file *dst)
> > {
> > -     bool found = false;
> >       long timeout;
> > -     struct nfsd4_ssc_umount_item *tmp;
> > -     struct nfsd4_ssc_umount_item *ni = NULL;
> >       struct nfsd_net *nn = net_generic(dst->nf_net, nfsd_net_id);
> >
> >       nfs42_ssc_close(filp);
> >       nfsd_file_put(dst);
> >       fput(filp);
> >
> > -     if (!nn) {
> > -             mntput(ss_mnt);
> > -             return;
> > -     }
> >       spin_lock(&nn->nfsd_ssc_lock);
> >       timeout = msecs_to_jiffies(nfsd4_ssc_umount_timeout);
> > -     list_for_each_entry_safe(ni, tmp, &nn->nfsd_ssc_mount_list, nsui_list) {
> > -             if (ni->nsui_vfsmount->mnt_sb == ss_mnt->mnt_sb) {
> > -                     list_del(&ni->nsui_list);
> > -                     /*
> > -                      * vfsmount can be shared by multiple exports,
> > -                      * decrement refcnt. If the count drops to 1 it
> > -                      * will be unmounted when nsui_expire expires.
> > -                      */
> > -                     refcount_dec(&ni->nsui_refcnt);
> > -                     ni->nsui_expire = jiffies + timeout;
> > -                     list_add_tail(&ni->nsui_list, &nn->nfsd_ssc_mount_list);
> > -                     found = true;
> > -                     break;
> > -             }
> > -     }
> > +     list_del(&ni->nsui_list);
> > +     /*
> > +      * vfsmount can be shared by multiple exports,
> > +      * decrement refcnt. If the count drops to 1 it
> > +      * will be unmounted when nsui_expire expires.
> > +      */
> > +     refcount_dec(&ni->nsui_refcnt);
> > +     ni->nsui_expire = jiffies + timeout;
> > +     list_add_tail(&ni->nsui_list, &nn->nfsd_ssc_mount_list);
> >       spin_unlock(&nn->nfsd_ssc_lock);
> > -     if (!found) {
> > -             mntput(ss_mnt);
> > -             return;
> > -     }
> > }
> >
> > #else /* CONFIG_NFSD_V4_2_INTER_SSC */
> >
> > static __be32
> > nfsd4_setup_inter_ssc(struct svc_rqst *rqstp,
> > -                   struct nfsd4_compound_state *cstate,
> > -                   struct nfsd4_copy *copy,
> > -                   struct vfsmount **mount)
> > +                     struct nfsd4_compound_state *cstate,
> > +                     struct nfsd4_copy *copy)
> > {
> > -     *mount = NULL;
> >       return nfserr_inval;
> > }
> >
> > static void
> > -nfsd4_cleanup_inter_ssc(struct vfsmount *ss_mnt, struct file *filp,
> > +nfsd4_cleanup_inter_ssc(struct nfsd4_ssc_umount_item *ni, struct file *filp,
> >                       struct nfsd_file *dst)
> > {
> > }
> > @@ -1700,7 +1679,7 @@ static void dup_copy_fields(struct nfsd4_copy *src, struct nfsd4_copy *dst)
> >       memcpy(dst->cp_src, src->cp_src, sizeof(struct nl4_server));
> >       memcpy(&dst->stateid, &src->stateid, sizeof(src->stateid));
> >       memcpy(&dst->c_fh, &src->c_fh, sizeof(src->c_fh));
> > -     dst->ss_mnt = src->ss_mnt;
> > +     dst->ss_nsui = src->ss_nsui;
> > }
> >
> > static void cleanup_async_copy(struct nfsd4_copy *copy)
> > @@ -1749,8 +1728,8 @@ static int nfsd4_do_async_copy(void *data)
> >       if (nfsd4_ssc_is_inter(copy)) {
> >               struct file *filp;
> >
> > -             filp = nfs42_ssc_open(copy->ss_mnt, &copy->c_fh,
> > -                                   &copy->stateid);
> > +             filp = nfs42_ssc_open(copy->ss_nsui->nsui_vfsmount,
> > +                             &copy->c_fh, &copy->stateid);
> >               if (IS_ERR(filp)) {
> >                       switch (PTR_ERR(filp)) {
> >                       case -EBADF:
> > @@ -1764,7 +1743,7 @@ static int nfsd4_do_async_copy(void *data)
> >               }
> >               nfserr = nfsd4_do_copy(copy, filp, copy->nf_dst->nf_file,
> >                                      false);
> > -             nfsd4_cleanup_inter_ssc(copy->ss_mnt, filp, copy->nf_dst);
> > +             nfsd4_cleanup_inter_ssc(copy->ss_nsui, filp, copy->nf_dst);
> >       } else {
> >               nfserr = nfsd4_do_copy(copy, copy->nf_src->nf_file,
> >                                      copy->nf_dst->nf_file, false);
> > @@ -1790,8 +1769,7 @@ nfsd4_copy(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> >                       status = nfserr_notsupp;
> >                       goto out;
> >               }
> > -             status = nfsd4_setup_inter_ssc(rqstp, cstate, copy,
> > -                             &copy->ss_mnt);
> > +             status = nfsd4_setup_inter_ssc(rqstp, cstate, copy);
> >               if (status)
> >                       return nfserr_offload_denied;
> >       } else {
> > diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
> > index 0eb00105d845..36c3340c1d54 100644
> > --- a/fs/nfsd/xdr4.h
> > +++ b/fs/nfsd/xdr4.h
> > @@ -571,7 +571,7 @@ struct nfsd4_copy {
> >       struct task_struct      *copy_task;
> >       refcount_t              refcount;
> >
> > -     struct vfsmount         *ss_mnt;
> > +     struct nfsd4_ssc_umount_item *ss_nsui;
> >       struct nfs_fh           c_fh;
> >       nfs4_stateid            stateid;
> > };
> > diff --git a/include/linux/nfs_ssc.h b/include/linux/nfs_ssc.h
> > index 75843c00f326..22265b1ff080 100644
> > --- a/include/linux/nfs_ssc.h
> > +++ b/include/linux/nfs_ssc.h
> > @@ -53,6 +53,7 @@ static inline void nfs42_ssc_close(struct file *filep)
> >       if (nfs_ssc_client_tbl.ssc_nfs4_ops)
> >               (*nfs_ssc_client_tbl.ssc_nfs4_ops->sco_close)(filep);
> > }
> > +#endif
> >
> > struct nfsd4_ssc_umount_item {
> >       struct list_head nsui_list;
> > @@ -66,7 +67,6 @@ struct nfsd4_ssc_umount_item {
> >       struct vfsmount *nsui_vfsmount;
> >       char nsui_ipaddr[RPC_MAX_ADDRBUFLEN + 1];
> > };
> > -#endif
> >
> > /*
> >  * NFS_FS
> > --
> > 2.9.5
> >
>
> --
> Chuck Lever
>
>
>