by Jeff Layton

[permalink] [raw]

Subject: Re: [PATCH 13/13] nfsd: allow layout state to be admin-revoked.

On Wed, 2024-01-31 at 09:13 +1100, NeilBrown wrote:
> On Tue, 30 Jan 2024, Jeff Layton wrote:
> > On Tue, 2024-01-30 at 12:08 +1100, NeilBrown wrote:
> > > When there is layout state on a filesystem that is being "unlocked" that
> > > is now revoked, which involves closing the nfsd_file and releasing the
> > > vfs lease.
> > >
> > > To avoid races, ->ls_file can now be accessed either:
> > > - under ->fi_lock for the state's sc_file or
> > > - under rcu_read_lock() if nfsd_file_get() is used.
> > > To support this, ->fence_client and nfsd4_cb_layout_fail() now take a
> > > second argument being the nfsd_file.
> > >
> > > Signed-off-by: NeilBrown <[email protected]>
> > > ---
> > > fs/nfsd/blocklayout.c | 4 ++--
> > > fs/nfsd/nfs4layouts.c | 43 ++++++++++++++++++++++++++++++++-----------
> > > fs/nfsd/nfs4state.c | 11 +++++++++--
> > > fs/nfsd/pnfs.h | 8 +++++++-
> > > 4 files changed, 50 insertions(+), 16 deletions(-)
> > >
> > > diff --git a/fs/nfsd/blocklayout.c b/fs/nfsd/blocklayout.c
> > > index 46fd74d91ea9..3c040c81c77d 100644
> > > --- a/fs/nfsd/blocklayout.c
> > > +++ b/fs/nfsd/blocklayout.c
> > > @@ -328,10 +328,10 @@ nfsd4_scsi_proc_layoutcommit(struct inode *inode,
> > > }
> > >
> > > static void
> > > -nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls)
> > > +nfsd4_scsi_fence_client(struct nfs4_layout_stateid *ls, struct nfsd_file *file)
> > > {
> > > struct nfs4_client *clp = ls->ls_stid.sc_client;
> > > - struct block_device *bdev = ls->ls_file->nf_file->f_path.mnt->mnt_sb->s_bdev;
> > > + struct block_device *bdev = file->nf_file->f_path.mnt->mnt_sb->s_bdev;
> > >
> > > bdev->bd_disk->fops->pr_ops->pr_preempt(bdev, NFSD_MDS_PR_KEY,
> > > nfsd4_scsi_pr_key(clp), 0, true);
> > > diff --git a/fs/nfsd/nfs4layouts.c b/fs/nfsd/nfs4layouts.c
> > > index 857b822450b4..1cfd61db2472 100644
> > > --- a/fs/nfsd/nfs4layouts.c
> > > +++ b/fs/nfsd/nfs4layouts.c
> > > @@ -152,6 +152,23 @@ void nfsd4_setup_layout_type(struct svc_export *exp)
> > > #endif
> > > }
> > >
> > > +void nfsd4_close_layout(struct nfs4_layout_stateid *ls)
> > > +{
> > > + struct nfsd_file *fl;
> > > +
> > > + spin_lock(&ls->ls_stid.sc_file->fi_lock);
> > > + fl = ls->ls_file;
> > > + ls->ls_file = NULL;
> > > + spin_unlock(&ls->ls_stid.sc_file->fi_lock);
> > > +
> > > + if (fl) {
> > > + if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls)
> > > + vfs_setlease(fl->nf_file, F_UNLCK, NULL,
> > > + (void **)&ls);
> > > + nfsd_file_put(fl);
> > > + }
> > > +}
> > > +
> > > static void
> > > nfsd4_free_layout_stateid(struct nfs4_stid *stid)
> > > {
> > > @@ -169,9 +186,7 @@ nfsd4_free_layout_stateid(struct nfs4_stid *stid)
> > > list_del_init(&ls->ls_perfile);
> > > spin_unlock(&fp->fi_lock);
> > >
> > > - if (!nfsd4_layout_ops[ls->ls_layout_type]->disable_recalls)
> > > - vfs_setlease(ls->ls_file->nf_file, F_UNLCK, NULL, (void **)&ls);
> > > - nfsd_file_put(ls->ls_file);
> > > + nfsd4_close_layout(ls);
> > >
> > > if (ls->ls_recalled)
> > > atomic_dec(&ls->ls_stid.sc_file->fi_lo_recalls);
> > > @@ -605,7 +620,7 @@ nfsd4_return_all_file_layouts(struct nfs4_client *clp, struct nfs4_file *fp)
> > > }
> > >
> > > static void
> > > -nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
> > > +nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls, struct nfsd_file *file)
> > > {
> > > struct nfs4_client *clp = ls->ls_stid.sc_client;
> > > char addr_str[INET6_ADDRSTRLEN];
> > > @@ -627,7 +642,7 @@ nfsd4_cb_layout_fail(struct nfs4_layout_stateid *ls)
> > >
> > > argv[0] = (char *)nfsd_recall_failed;
> > > argv[1] = addr_str;
> > > - argv[2] = ls->ls_file->nf_file->f_path.mnt->mnt_sb->s_id;
> > > + argv[2] = file->nf_file->f_path.mnt->mnt_sb->s_id;
> > > argv[3] = NULL;
> > >
> > > error = call_usermodehelper(nfsd_recall_failed, argv, envp,
> > > @@ -657,6 +672,7 @@ nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
> > > struct nfsd_net *nn;
> > > ktime_t now, cutoff;
> > > const struct nfsd4_layout_ops *ops;
> > > + struct nfsd_file *fl;
> > >
> > > trace_nfsd_cb_layout_done(&ls->ls_stid.sc_stateid, task);
> > > switch (task->tk_status) {
> > > @@ -688,12 +704,17 @@ nfsd4_cb_layout_done(struct nfsd4_callback *cb, struct rpc_task *task)
> > > * Unknown error or non-responding client, we'll need to fence.
> > > */
> > > trace_nfsd_layout_recall_fail(&ls->ls_stid.sc_stateid);
> > > -
> > > - ops = nfsd4_layout_ops[ls->ls_layout_type];
> > > - if (ops->fence_client)
> > > - ops->fence_client(ls);
> > > - else
> > > - nfsd4_cb_layout_fail(ls);
> > > + rcu_read_lock();
> > > + fl = nfsd_file_get(ls->ls_file);
> > > + rcu_read_unlock();
> >
> > I'm still wondering about the rcu_read_lock above. It's probably
> > harmless, but it seems unnecessary since you already hold a reference to
> > "ls". Is there a reason for it?
>
> I replied !
>
> https://lore.kernel.org/linux-nfs/[email protected]/
>
> See nfsd4_close_layout(). A ref on ls doesn't guarantee a ref on
> ls->ls_file any more.
>
>

Hmmm... I never received that reply.

The answer makes sense though, thanks. You can add my Reviewed-by to
13/13 as well.

Cheers,

> >
> > > + if (fl) {
> > > + ops = nfsd4_layout_ops[ls->ls_layout_type];
> > > + if (ops->fence_client)
> > > + ops->fence_client(ls, fl);
> > > + else
> > > + nfsd4_cb_layout_fail(ls, fl);
> > > + nfsd_file_put(fl);
> > > + }
> > > return 1;
> > > case -NFS4ERR_NOMATCHING_LAYOUT:
> > > trace_nfsd_layout_recall_done(&ls->ls_stid.sc_stateid);
> > > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > > index fe21af8dfc68..a66d66b9f769 100644
> > > --- a/fs/nfsd/nfs4state.c
> > > +++ b/fs/nfsd/nfs4state.c
> > > @@ -1721,7 +1721,7 @@ void nfsd4_revoke_states(struct net *net, struct super_block *sb)
> > > unsigned int idhashval;
> > > unsigned int sc_types;
> > >
> > > - sc_types = SC_TYPE_OPEN | SC_TYPE_LOCK | SC_TYPE_DELEG;
> > > + sc_types = SC_TYPE_OPEN | SC_TYPE_LOCK | SC_TYPE_DELEG | SC_TYPE_LAYOUT;
> > >
> > > spin_lock(&nn->client_lock);
> > > for (idhashval = 0; idhashval < CLIENT_HASH_MASK; idhashval++) {
> > > @@ -1734,6 +1734,7 @@ void nfsd4_revoke_states(struct net *net, struct super_block *sb)
> > > if (stid) {
> > > struct nfs4_ol_stateid *stp;
> > > struct nfs4_delegation *dp;
> > > + struct nfs4_layout_stateid *ls;
> > >
> > > spin_unlock(&nn->client_lock);
> > > switch (stid->sc_type) {
> > > @@ -1789,6 +1790,10 @@ void nfsd4_revoke_states(struct net *net, struct super_block *sb)
> > > if (dp)
> > > revoke_delegation(dp);
> > > break;
> > > + case SC_TYPE_LAYOUT:
> > > + ls = layoutstateid(stid);
> > > + nfsd4_close_layout(ls);
> > > + break;
> > > }
> > > nfs4_put_stid(stid);
> > > spin_lock(&nn->client_lock);
> > > @@ -2868,7 +2873,6 @@ static int nfs4_show_layout(struct seq_file *s, struct nfs4_stid *st)
> > > struct nfsd_file *file;
> > >
> > > ls = container_of(st, struct nfs4_layout_stateid, ls_stid);
> > > - file = ls->ls_file;
> > >
> > > seq_puts(s, "- ");
> > > nfs4_show_stateid(s, &st->sc_stateid);
> > > @@ -2876,12 +2880,15 @@ static int nfs4_show_layout(struct seq_file *s, struct nfs4_stid *st)
> > >
> > > /* XXX: What else would be useful? */
> > >
> > > + spin_lock(&ls->ls_stid.sc_file->fi_lock);
> > > + file = ls->ls_file;
> > > if (file) {
> > > seq_puts(s, ", ");
> > > nfs4_show_superblock(s, file);
> > > seq_puts(s, ", ");
> > > nfs4_show_fname(s, file);
> > > }
> > > + spin_unlock(&ls->ls_stid.sc_file->fi_lock);
> > > if (st->sc_status & SC_STATUS_ADMIN_REVOKED)
> > > seq_puts(s, ", admin-revoked");
> > > seq_puts(s, " }\n");
> > > diff --git a/fs/nfsd/pnfs.h b/fs/nfsd/pnfs.h
> > > index de1e0dfed06a..925817f66917 100644
> > > --- a/fs/nfsd/pnfs.h
> > > +++ b/fs/nfsd/pnfs.h
> > > @@ -37,7 +37,8 @@ struct nfsd4_layout_ops {
> > > __be32 (*proc_layoutcommit)(struct inode *inode,
> > > struct nfsd4_layoutcommit *lcp);
> > >
> > > - void (*fence_client)(struct nfs4_layout_stateid *ls);
> > > + void (*fence_client)(struct nfs4_layout_stateid *ls,
> > > + struct nfsd_file *file);
> > > };
> > >
> > > extern const struct nfsd4_layout_ops *nfsd4_layout_ops[];
> > > @@ -72,11 +73,13 @@ void nfsd4_setup_layout_type(struct svc_export *exp);
> > > void nfsd4_return_all_client_layouts(struct nfs4_client *);
> > > void nfsd4_return_all_file_layouts(struct nfs4_client *clp,
> > > struct nfs4_file *fp);
> > > +void nfsd4_close_layout(struct nfs4_layout_stateid *ls);
> > > int nfsd4_init_pnfs(void);
> > > void nfsd4_exit_pnfs(void);
> > > #else
> > > struct nfs4_client;
> > > struct nfs4_file;
> > > +struct nfs4_layout_stateid;
> > >
> > > static inline void nfsd4_setup_layout_type(struct svc_export *exp)
> > > {
> > > @@ -89,6 +92,9 @@ static inline void nfsd4_return_all_file_layouts(struct nfs4_client *clp,
> > > struct nfs4_file *fp)
> > > {
> > > }
> > > +static inline void nfsd4_close_layout(struct nfs4_layout_stateid *ls)
> > > +{
> > > +}
> > > static inline void nfsd4_exit_pnfs(void)
> > > {
> > > }
> >
> > --
> > Jeff Layton <[email protected]>
> >
> >
>

--
Jeff Layton <[email protected]>

2024-01-31 15:36:27

by Chuck Lever III

[permalink] [raw]

Subject: Re: [PATCH 00/13 v5] nfsd: support admin-revocation of v4 state

> On Jan 29, 2024, at 8:08 PM, NeilBrown <[email protected]> wrote:
>
> Changes compared to V4:
> - rebased on nfsd-next. There was a new trace point which caused a conflict
> - added some reviewed-by from Jeff
> - Fix the new kdoc comment - kernel test robot reported I had the wrong
> syntax for documenting function parameters.
>
> Thanks,
> NeilBrown
>
> [PATCH 01/13] nfsd: remove stale comment in nfs4_show_deleg()
> [PATCH 02/13] nfsd: hold ->cl_lock for hash_delegation_locked()
> [PATCH 03/13] nfsd: don't call functions with side-effecting inside
> [PATCH 04/13] nfsd: avoid race after unhash_delegation_locked()
> [PATCH 05/13] nfsd: split sc_status out of sc_type
> [PATCH 06/13] nfsd: prepare for supporting admin-revocation of state
> [PATCH 07/13] nfsd: allow state with no file to appear in
> [PATCH 08/13] nfsd: report in /proc/fs/nfsd/clients/*/states when
> [PATCH 09/13] nfsd: allow admin-revoked NFSv4.0 state to be freed.
> [PATCH 10/13] nfsd: allow lock state ids to be revoked and then freed
> [PATCH 11/13] nfsd: allow open state ids to be revoked and then freed
> [PATCH 12/13] nfsd: allow delegation state ids to be revoked and then
> [PATCH 13/13] nfsd: allow layout state to be admin-revoked.

Applied to nfsd-next (for v6.9). Review comments still welcome.

--
Chuck Lever