Skip to content

Commit

Permalink
nfsd: have nfsd4_lock use blocking locks for v4.1+ locks
Browse files Browse the repository at this point in the history 
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.

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@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
  • Loading branch information
Jeff Layton authored and J. Bruce Fields committed Sep 26, 2016
1 parent a188620 commit 76d348f
Show file tree
Hide file tree
Showing 2 changed files with 156 additions and 20 deletions.
164 changes: 147 additions & 17 deletions fs/nfsd/nfs4state.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
{
Expand Down Expand Up @@ -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)
{
Expand Down Expand Up @@ -5309,7 +5388,29 @@ 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,
};
Expand Down Expand Up @@ -5407,6 +5508,7 @@ 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;
Expand Down Expand Up @@ -5588,12 +5690,15 @@ 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;
unsigned int fl_flags = FL_POSIX;
struct net *net = SVC_NET(rqstp);
struct nfsd_net *nn = net_generic(net, nfsd_net_id);

Expand Down Expand Up @@ -5658,46 +5763,55 @@ 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:
case NFS4_READW_LT:
if (nfsd4_has_session(cstate))
fl_flags |= FL_SLEEP;
/* Fallthrough */
case NFS4_READ_LT:
spin_lock(&fp->fi_lock);
filp = find_readable_file_locked(fp);
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:
if (nfsd4_has_session(cstate))
fl_flags |= FL_SLEEP;
/* Fallthrough */
case NFS4_WRITE_LT:
spin_lock(&fp->fi_lock);
filp = find_writeable_file_locked(fp);
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;
file_lock->fl_flags = FL_POSIX;
file_lock->fl_flags = fl_flags;
file_lock->fl_lmops = &nfsd_posix_mng_ops;
file_lock->fl_start = lock->lk_offset;
file_lock->fl_end = last_byte_offset(lock->lk_offset, lock->lk_length);
Expand All @@ -5710,18 +5824,27 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
goto out;
}

if (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:
Expand All @@ -5730,6 +5853,15 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
break;
}
out:
if (nbl) {
/* dequeue it if we queued it before */
if (fl_flags & FL_SLEEP) {
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) {
Expand All @@ -5753,8 +5885,6 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
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;
Expand Down
12 changes: 9 additions & 3 deletions fs/nfsd/state.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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)
Expand Down Expand Up @@ -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;
Expand Down

0 comments on commit 76d348f

Please sign in to comment.