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nfsd: move blocked lock handling under a dedicated spinlock

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Bruce was hitting some lockdep warnings in testing, showing that we
could hit a deadlock with the new CB_NOTIFY_LOCK handling, involving a
rather complex situation involving four different spinlocks.

The crux of the matter is that we end up taking the nn->client_lock in
the lm_notify handler. The simplest fix is to just declare a new
per-nfsd_net spinlock to protect the new CB_NOTIFY_LOCK structures.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
This commit is contained in:
Jeff Layton 2016-10-20 09:34:31 -04:00 committed by J. Bruce Fields
parent 07d9a38068
commit 0cc11a61b8
2 changed files with 20 additions and 13 deletions
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5
fs/nfsd/netns.h
View File

@ -84,6 +84,8 @@ struct nfsd_net {
struct list_head client_lru;
struct list_head close_lru;
struct list_head del_recall_lru;
/* protected by blocked_locks_lock */
struct list_head blocked_locks_lru;
struct delayed_work laundromat_work;
@ -91,6 +93,9 @@ struct nfsd_net {
/* client_lock protects the client lru list and session hash table */
spinlock_t client_lock;
/* protects blocked_locks_lru */
spinlock_t blocked_locks_lock;
struct file *rec_file;
bool in_grace;
const struct nfsd4_client_tracking_ops *client_tracking_ops;

28
fs/nfsd/nfs4state.c
View File

@ -217,7 +217,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
{
struct nfsd4_blocked_lock *cur, *found = NULL;
spin_lock(&nn->client_lock);
spin_lock(&nn->blocked_locks_lock);
list_for_each_entry(cur, &lo->lo_blocked, nbl_list) {
if (fh_match(fh, &cur->nbl_fh)) {
list_del_init(&cur->nbl_list);
@ -226,7 +226,7 @@ find_blocked_lock(struct nfs4_lockowner *lo, struct knfsd_fh *fh,
break;
}
}
spin_unlock(&nn->client_lock);
spin_unlock(&nn->blocked_locks_lock);
if (found)
posix_unblock_lock(&found->nbl_lock);
return found;
@ -4665,7 +4665,7 @@ nfs4_laundromat(struct nfsd_net *nn)
* indefinitely once the lock does become free.
*/
BUG_ON(!list_empty(&reaplist));
spin_lock(&nn->client_lock);
spin_lock(&nn->blocked_locks_lock);
while (!list_empty(&nn->blocked_locks_lru)) {
nbl = list_first_entry(&nn->blocked_locks_lru,
struct nfsd4_blocked_lock, nbl_lru);
@ -4678,7 +4678,7 @@ nfs4_laundromat(struct nfsd_net *nn)
list_move(&nbl->nbl_lru, &reaplist);
list_del_init(&nbl->nbl_list);
}
spin_unlock(&nn->client_lock);
spin_unlock(&nn->blocked_locks_lock);
while (!list_empty(&reaplist)) {
nbl = list_first_entry(&nn->blocked_locks_lru,
@ -5439,13 +5439,13 @@ nfsd4_lm_notify(struct file_lock *fl)
bool queue = false;
/* An empty list means that something else is going to be using it */
spin_lock(&nn->client_lock);
spin_lock(&nn->blocked_locks_lock);
if (!list_empty(&nbl->nbl_list)) {
list_del_init(&nbl->nbl_list);
list_del_init(&nbl->nbl_lru);
queue = true;
}
spin_unlock(&nn->client_lock);
spin_unlock(&nn->blocked_locks_lock);
if (queue)
nfsd4_run_cb(&nbl->nbl_cb);
@ -5868,10 +5868,10 @@ nfsd4_lock(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
if (fl_flags & FL_SLEEP) {
nbl->nbl_time = jiffies;
spin_lock(&nn->client_lock);
spin_lock(&nn->blocked_locks_lock);
list_add_tail(&nbl->nbl_list, &lock_sop->lo_blocked);
list_add_tail(&nbl->nbl_lru, &nn->blocked_locks_lru);
spin_unlock(&nn->client_lock);
spin_unlock(&nn->blocked_locks_lock);
}
err = vfs_lock_file(filp, F_SETLK, file_lock, conflock);
@ -5900,10 +5900,10 @@ out:
if (nbl) {
/* dequeue it if we queued it before */
if (fl_flags & FL_SLEEP) {
spin_lock(&nn->client_lock);
spin_lock(&nn->blocked_locks_lock);
list_del_init(&nbl->nbl_list);
list_del_init(&nbl->nbl_lru);
spin_unlock(&nn->client_lock);
spin_unlock(&nn->blocked_locks_lock);
}
free_blocked_lock(nbl);
}
@ -6943,9 +6943,11 @@ static int nfs4_state_create_net(struct net *net)
INIT_LIST_HEAD(&nn->client_lru);
INIT_LIST_HEAD(&nn->close_lru);
INIT_LIST_HEAD(&nn->del_recall_lru);
INIT_LIST_HEAD(&nn->blocked_locks_lru);
spin_lock_init(&nn->client_lock);
spin_lock_init(&nn->blocked_locks_lock);
INIT_LIST_HEAD(&nn->blocked_locks_lru);
INIT_DELAYED_WORK(&nn->laundromat_work, laundromat_main);
get_net(net);
@ -7063,14 +7065,14 @@ nfs4_state_shutdown_net(struct net *net)
}
BUG_ON(!list_empty(&reaplist));
spin_lock(&nn->client_lock);
spin_lock(&nn->blocked_locks_lock);
while (!list_empty(&nn->blocked_locks_lru)) {
nbl = list_first_entry(&nn->blocked_locks_lru,
struct nfsd4_blocked_lock, nbl_lru);
list_move(&nbl->nbl_lru, &reaplist);
list_del_init(&nbl->nbl_list);
}
spin_unlock(&nn->client_lock);
spin_unlock(&nn->blocked_locks_lock);
while (!list_empty(&reaplist)) {
nbl = list_first_entry(&nn->blocked_locks_lru,