On Tue, Aug 02, 2016 at 02:15:29PM -0400, Jeff Layton wrote:
> Create a new per-lockowner+per-inode structure that contains a
> file_lock. Have nfsd4_lock add this structure to the lockowner's list
> prior to setting the lock. Then call the vfs and request a blocking lock
> (by setting FL_SLEEP). If we get anything besides FILE_LOCK_DEFERRED
> back, then we dequeue the block structure and free it. When the next
> lock request comes in, we'll look for an existing block for the same
> filehandle and dequeue and reuse it if there is one.
I'm probably just missing it because I only skimmed the patch quickly,
but I don't see you distinguishing the blocking and non-blocking case.
I think we only want to do this in the {READ,WRITE}W_LT case, as
{READ,WRITE}_LT is a hint from the client that it's not going to wait
for the lock. Sending a notify without a preceding blocking request is
probably a (relatively harmless) protocol bug.
--b.
>
> When the lock comes free (a'la an lm_notify call), we dequeue it
> from the lockowner's list and kick off a CB_NOTIFY_LOCK callback to
> inform the client that it should retry the lock request.
>
> Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxx>
> ---
> fs/nfsd/nfs4state.c | 152 +++++++++++++++++++++++++++++++++++++++++++++++-----
> fs/nfsd/state.h | 12 +++--
> 2 files changed, 147 insertions(+), 17 deletions(-)
>
> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> index 70d0b9b33031..38367201c14f 100644
> --- a/fs/nfsd/nfs4state.c
> +++ b/fs/nfsd/nfs4state.c
> @@ -99,6 +99,7 @@ static struct kmem_cache *odstate_slab;
> static void free_session(struct nfsd4_session *);
>
> static const struct nfsd4_callback_ops nfsd4_cb_recall_ops;
> +static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops;
>
> static bool is_session_dead(struct nfsd4_session *ses)
> {
> @@ -210,6 +211,84 @@ static void nfsd4_put_session(struct nfsd4_session *ses)
> spin_unlock(&nn->client_lock);
> }
>
> +static struct nfsd4_blocked_lock *
> +find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
> + struct nfsd_net *nn)
> +{
> + struct nfsd4_blocked_lock *cur, *found = NULL;
> +
> + spin_lock(&nn->client_lock);
> + list_for_each_entry(cur, &lo->lo_blocked, nbl_list) {
> + if (fh_match(fh, &cur->nbl_fh)) {
> + list_del_init(&cur->nbl_list);
> + found = cur;
> + break;
> + }
> + }
> + spin_unlock(&nn->client_lock);
> + if (found)
> + posix_unblock_lock(&found->nbl_lock);
> + return found;
> +}
> +
> +static struct nfsd4_blocked_lock *
> +find_or_allocate_block(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
> + struct nfsd_net *nn)
> +{
> + struct nfsd4_blocked_lock *nbl;
> +
> + nbl = find_blocked_lock(lo, fh, nn);
> + if (!nbl) {
> + nbl= kmalloc(sizeof(*nbl), GFP_KERNEL);
> + if (nbl) {
> + fh_copy_shallow(&nbl->nbl_fh, fh);
> + locks_init_lock(&nbl->nbl_lock);
> + nfsd4_init_cb(&nbl->nbl_cb, lo->lo_owner.so_client,
> + &nfsd4_cb_notify_lock_ops,
> + NFSPROC4_CLNT_CB_NOTIFY_LOCK);
> + }
> + }
> + return nbl;
> +}
> +
> +static void
> +free_blocked_lock(struct nfsd4_blocked_lock *nbl)
> +{
> + locks_release_private(&nbl->nbl_lock);
> + kfree(nbl);
> +}
> +
> +static int
> +nfsd4_cb_notify_lock_done(struct nfsd4_callback *cb, struct rpc_task *task)
> +{
> + /*
> + * Since this is just an optimization, we don't try very hard if it
> + * turns out not to succeed. We'll requeue it on NFS4ERR_DELAY, and
> + * just quit trying on anything else.
> + */
> + switch (task->tk_status) {
> + case -NFS4ERR_DELAY:
> + rpc_delay(task, 1 * HZ);
> + return 0;
> + default:
> + return 1;
> + }
> +}
> +
> +static void
> +nfsd4_cb_notify_lock_release(struct nfsd4_callback *cb)
> +{
> + struct nfsd4_blocked_lock *nbl = container_of(cb,
> + struct nfsd4_blocked_lock, nbl_cb);
> +
> + free_blocked_lock(nbl);
> +}
> +
> +static const struct nfsd4_callback_ops nfsd4_cb_notify_lock_ops = {
> + .done = nfsd4_cb_notify_lock_done,
> + .release = nfsd4_cb_notify_lock_release,
> +};
> +
> static inline struct nfs4_stateowner *
> nfs4_get_stateowner(struct nfs4_stateowner *sop)
> {
> @@ -5296,7 +5375,29 @@ nfsd4_fl_put_owner(fl_owner_t owner)
> nfs4_put_stateowner(&lo->lo_owner);
> }
>
> +static void
> +nfsd4_lm_notify(struct file_lock *fl)
> +{
> + struct nfs4_lockowner *lo = (struct nfs4_lockowner *)fl->fl_owner;
> + struct net *net = lo->lo_owner.so_client->net;
> + struct nfsd_net *nn = net_generic(net, nfsd_net_id);
> + struct nfsd4_blocked_lock *nbl = container_of(fl,
> + struct nfsd4_blocked_lock, nbl_lock);
> + bool queue = false;
> +
> + spin_lock(&nn->client_lock);
> + if (!list_empty(&nbl->nbl_list)) {
> + list_del_init(&nbl->nbl_list);
> + queue = true;
> + }
> + spin_unlock(&nn->client_lock);
> +
> + if (queue)
> + nfsd4_run_cb(&nbl->nbl_cb);
> +}
> +
> static const struct lock_manager_operations nfsd_posix_mng_ops = {
> + .lm_notify = nfsd4_lm_notify,
> .lm_get_owner = nfsd4_fl_get_owner,
> .lm_put_owner = nfsd4_fl_put_owner,
> };
> @@ -5394,6 +5495,7 @@ alloc_init_lock_stateowner(unsigned int strhashval, struct nfs4_client *clp,
> lo = alloc_stateowner(lockowner_slab, &lock->lk_new_owner, clp);
> if (!lo)
> return NULL;
> + INIT_LIST_HEAD(&lo->lo_blocked);
> INIT_LIST_HEAD(&lo->lo_owner.so_stateids);
> lo->lo_owner.so_is_open_owner = 0;
> lo->lo_owner.so_seqid = lock->lk_new_lock_seqid;
> @@ -5558,12 +5660,14 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> struct nfs4_ol_stateid *open_stp = NULL;
> struct nfs4_file *fp;
> struct file *filp = NULL;
> + struct nfsd4_blocked_lock *nbl = NULL;
> struct file_lock *file_lock = NULL;
> struct file_lock *conflock = NULL;
> __be32 status = 0;
> int lkflg;
> int err;
> bool new = false;
> + unsigned char fl_type;
> struct net *net = SVC_NET(rqstp);
> struct nfsd_net *nn = net_generic(net, nfsd_net_id);
>
> @@ -5630,13 +5734,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> if (!locks_in_grace(net) && lock->lk_reclaim)
> goto out;
>
> - file_lock = locks_alloc_lock();
> - if (!file_lock) {
> - dprintk("NFSD: %s: unable to allocate lock!\n", __func__);
> - status = nfserr_jukebox;
> - goto out;
> - }
> -
> fp = lock_stp->st_stid.sc_file;
> switch (lock->lk_type) {
> case NFS4_READ_LT:
> @@ -5646,7 +5743,7 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> if (filp)
> get_lock_access(lock_stp, NFS4_SHARE_ACCESS_READ);
> spin_unlock(&fp->fi_lock);
> - file_lock->fl_type = F_RDLCK;
> + fl_type = F_RDLCK;
> break;
> case NFS4_WRITE_LT:
> case NFS4_WRITEW_LT:
> @@ -5655,17 +5752,27 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> if (filp)
> get_lock_access(lock_stp, NFS4_SHARE_ACCESS_WRITE);
> spin_unlock(&fp->fi_lock);
> - file_lock->fl_type = F_WRLCK;
> + fl_type = F_WRLCK;
> break;
> default:
> status = nfserr_inval;
> goto out;
> }
> +
> if (!filp) {
> status = nfserr_openmode;
> goto out;
> }
>
> + nbl = find_or_allocate_block(lock_sop, &fp->fi_fhandle, nn);
> + if (!nbl) {
> + dprintk("NFSD: %s: unable to allocate block!\n", __func__);
> + status = nfserr_jukebox;
> + goto out;
> + }
> +
> + file_lock = &nbl->nbl_lock;
> + file_lock->fl_type = fl_type;
> file_lock->fl_owner = (fl_owner_t)lockowner(nfs4_get_stateowner(&lock_sop->lo_owner));
> file_lock->fl_pid = current->tgid;
> file_lock->fl_file = filp;
> @@ -5682,18 +5789,28 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> goto out;
> }
>
> + if (nfsd4_has_session(cstate)) {
> + file_lock->fl_flags |= FL_SLEEP;
> + spin_lock(&nn->client_lock);
> + list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked);
> + spin_unlock(&nn->client_lock);
> + }
> +
> err = vfs_lock_file(filp, F_SETLK, file_lock, conflock);
> - switch (-err) {
> + switch (err) {
> case 0: /* success! */
> nfs4_inc_and_copy_stateid(&lock->lk_resp_stateid, &lock_stp->st_stid);
> status = 0;
> break;
> - case (EAGAIN): /* conflock holds conflicting lock */
> + case FILE_LOCK_DEFERRED:
> + nbl = NULL;
> + /* Fallthrough */
> + case EAGAIN: /* conflock holds conflicting lock */
> status = nfserr_denied;
> dprintk("NFSD: nfsd4_lock: conflicting lock found!\n");
> nfs4_set_lock_denied(conflock, &lock->lk_denied);
> break;
> - case (EDEADLK):
> + case EDEADLK:
> status = nfserr_deadlock;
> break;
> default:
> @@ -5702,6 +5819,15 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
> break;
> }
> out:
> + if (nbl) {
> + /* dequeue it if we queued it before */
> + if (nfsd4_has_session(cstate)) {
> + spin_lock(&nn->client_lock);
> + list_del_init(&nbl->nbl_list);
> + spin_unlock(&nn->client_lock);
> + }
> + free_blocked_lock(nbl);
> + }
> if (filp)
> fput(filp);
> if (lock_stp) {
> @@ -5725,8 +5851,6 @@ out:
> if (open_stp)
> nfs4_put_stid(&open_stp->st_stid);
> nfsd4_bump_seqid(cstate, status);
> - if (file_lock)
> - locks_free_lock(file_lock);
> if (conflock)
> locks_free_lock(conflock);
> return status;
> diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
> index ecf3f4671654..056b0e4c485b 100644
> --- a/fs/nfsd/state.h
> +++ b/fs/nfsd/state.h
> @@ -440,11 +440,11 @@ struct nfs4_openowner {
> /*
> * Represents a generic "lockowner". Similar to an openowner. References to it
> * are held by the lock stateids that are created on its behalf. This object is
> - * a superset of the nfs4_stateowner struct (or would be if it needed any extra
> - * fields).
> + * a superset of the nfs4_stateowner struct.
> */
> struct nfs4_lockowner {
> - struct nfs4_stateowner lo_owner; /* must be first element */
> + struct nfs4_stateowner lo_owner; /* must be first element */
> + struct list_head lo_blocked; /* blocked file_locks */
> };
>
> static inline struct nfs4_openowner * openowner(struct nfs4_stateowner *so)
> @@ -580,7 +580,13 @@ static inline bool nfsd4_stateid_generation_after(stateid_t *a, stateid_t *b)
> return (s32)(a->si_generation - b->si_generation) > 0;
> }
>
> +/*
> + * When a client tries to get a lock on a file, we set one of these objects
> + * on the blocking lock. When the lock becomes free, we can then issue a
> + * CB_NOTIFY_LOCK to the server.
> + */
> struct nfsd4_blocked_lock {
> + struct list_head nbl_list;
> struct file_lock nbl_lock;
> struct knfsd_fh nbl_fh;
> struct nfsd4_callback nbl_cb;
> --
> 2.7.4
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