state_lock is a heavily contended global lock. We don't want to grab
that while simultaneously holding the inode->i_lock. Avoid doing that in
the delegation break callback by ensuring that we add/remove the
dl_perfile under a new per-nfs4_file fi_lock, and hold that while walking
the fi_delegations list.
We still do need to queue the delegations to the global del_recall_lru
list. Do that in the rpc_prepare op for the delegation recall RPC. It's
possible though that the allocation of the rpc_task will fail, which
would cause the delegation to be leaked.
If that occurs rpc_release is still called, so we also do it there if
the rpc_task failed to run. This brings up another dilemma -- how do
we know whether it got queued in rpc_prepare or not?
In order to determine that, we set the dl_time to 0 in the delegation
break callback from the VFS and only set it when we queue it to the
list. If it's still zero by the time we get to rpc_release, then we know
that it never got queued and we can do it then.
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Signed-off-by: Jeff Layton <jlayton@xxxxxxxxxxxxxxx>
---
fs/nfsd/nfs4callback.c | 9 ++++--
fs/nfsd/nfs4state.c | 74 +++++++++++++++++++++++++++++++++++++-------------
fs/nfsd/state.h | 2 ++
3 files changed, 64 insertions(+), 21 deletions(-)
diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
index 2c73cae9899d..3d01637d950c 100644
--- a/fs/nfsd/nfs4callback.c
+++ b/fs/nfsd/nfs4callback.c
@@ -810,12 +810,15 @@ static bool nfsd41_cb_get_slot(struct nfs4_client *clp, struct rpc_task *task)
* TODO: cb_sequence should support referring call lists, cachethis, multiple
* slots, and mark callback channel down on communication errors.
*/
-static void nfsd4_cb_prepare(struct rpc_task *task, void *calldata)
+static void nfsd4_cb_recall_prepare(struct rpc_task *task, void *calldata)
{
struct nfsd4_callback *cb = calldata;
struct nfs4_client *clp = cb->cb_clp;
+ struct nfs4_delegation *dp = container_of(cb, struct nfs4_delegation, dl_recall);
u32 minorversion = clp->cl_minorversion;
+ nfsd4_queue_to_del_recall_lru(dp);
+
cb->cb_minorversion = minorversion;
if (minorversion) {
if (!nfsd41_cb_get_slot(clp, task))
@@ -900,6 +903,8 @@ static void nfsd4_cb_recall_release(void *calldata)
struct nfs4_client *clp = cb->cb_clp;
struct nfs4_delegation *dp = container_of(cb, struct nfs4_delegation, dl_recall);
+ nfsd4_queue_to_del_recall_lru(dp);
+
if (cb->cb_done) {
spin_lock(&clp->cl_lock);
list_del(&cb->cb_per_client);
@@ -909,7 +914,7 @@ static void nfsd4_cb_recall_release(void *calldata)
}
static const struct rpc_call_ops nfsd4_cb_recall_ops = {
- .rpc_call_prepare = nfsd4_cb_prepare,
+ .rpc_call_prepare = nfsd4_cb_recall_prepare,
.rpc_call_done = nfsd4_cb_recall_done,
.rpc_release = nfsd4_cb_recall_release,
};
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index cbec573e9445..f429883fb4bb 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -438,7 +438,9 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
lockdep_assert_held(&state_lock);
dp->dl_stid.sc_type = NFS4_DELEG_STID;
+ spin_lock(&fp->fi_lock);
list_add(&dp->dl_perfile, &fp->fi_delegations);
+ spin_unlock(&fp->fi_lock);
list_add(&dp->dl_perclnt, &dp->dl_stid.sc_client->cl_delegations);
}
@@ -446,14 +448,20 @@ hash_delegation_locked(struct nfs4_delegation *dp, struct nfs4_file *fp)
static void
unhash_delegation(struct nfs4_delegation *dp)
{
+ struct nfs4_file *fp = dp->dl_file;
+
spin_lock(&state_lock);
list_del_init(&dp->dl_perclnt);
- list_del_init(&dp->dl_perfile);
list_del_init(&dp->dl_recall_lru);
+ if (!list_empty(&dp->dl_perfile)) {
+ spin_lock(&fp->fi_lock);
+ list_del_init(&dp->dl_perfile);
+ spin_unlock(&fp->fi_lock);
+ }
spin_unlock(&state_lock);
- if (dp->dl_file) {
- nfs4_put_deleg_lease(dp->dl_file);
- put_nfs4_file(dp->dl_file);
+ if (fp) {
+ nfs4_put_deleg_lease(fp);
+ put_nfs4_file(fp);
dp->dl_file = NULL;
}
}
@@ -2522,6 +2530,7 @@ static void nfsd4_init_file(struct nfs4_file *fp, struct inode *ino)
lockdep_assert_held(&state_lock);
atomic_set(&fp->fi_ref, 1);
+ spin_lock_init(&fp->fi_lock);
INIT_LIST_HEAD(&fp->fi_stateids);
INIT_LIST_HEAD(&fp->fi_delegations);
ihold(ino);
@@ -2767,23 +2776,49 @@ out:
return ret;
}
+/*
+ * We use a dl_time of 0 as an indicator that the delegation is "disconnected"
+ * from the client lists. If we find that that's the case, set the dl_time and
+ * then queue it to the list.
+ */
+void
+nfsd4_queue_to_del_recall_lru(struct nfs4_delegation *dp)
+{
+ struct nfs4_file *fp = dp->dl_file;
+ struct nfsd_net *nn = net_generic(dp->dl_stid.sc_client->net, nfsd_net_id);
+
+ spin_lock(&fp->fi_lock);
+ if (dp->dl_time) {
+ dp->dl_time = get_seconds();
+ spin_unlock(&fp->fi_lock);
+ spin_lock(&state_lock);
+ list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
+ spin_unlock(&state_lock);
+ } else {
+ spin_unlock(&fp->fi_lock);
+ }
+}
+
static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
{
- struct nfs4_client *clp = dp->dl_stid.sc_client;
- struct nfsd_net *nn = net_generic(clp->net, nfsd_net_id);
+ lockdep_assert_held(&dp->dl_file->fi_lock);
- lockdep_assert_held(&state_lock);
- /* We're assuming the state code never drops its reference
+ /*
+ * We're assuming the state code never drops its reference
* without first removing the lease. Since we're in this lease
- * callback (and since the lease code is serialized by the kernel
- * lock) we know the server hasn't removed the lease yet, we know
- * it's safe to take a reference: */
+ * callback (and since the lease code is serialized by the i_lock
+ * we know the server hasn't removed the lease yet, we know it's
+ * safe to take a reference.
+ */
atomic_inc(&dp->dl_count);
- list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
-
- /* Only place dl_time is set; protected by i_lock: */
- dp->dl_time = get_seconds();
+ /*
+ * We use a dl_time of 0 to indicate that the delegation has
+ * not yet been queued to the nn->del_recall_lru list. That's
+ * done in the rpc_prepare or rpc_release operations (depending
+ * on which one gets there first).
+ */
+ dp->dl_time = 0;
nfsd4_cb_recall(dp);
}
@@ -2809,11 +2844,11 @@ static void nfsd_break_deleg_cb(struct file_lock *fl)
*/
fl->fl_break_time = 0;
- spin_lock(&state_lock);
+ spin_lock(&fp->fi_lock);
fp->fi_had_conflict = true;
list_for_each_entry(dp, &fp->fi_delegations, dl_perfile)
nfsd_break_one_deleg(dp);
- spin_unlock(&state_lock);
+ spin_unlock(&fp->fi_lock);
}
static
@@ -3454,8 +3489,9 @@ nfs4_laundromat(struct nfsd_net *nn)
dp = list_entry (pos, struct nfs4_delegation, dl_recall_lru);
if (net_generic(dp->dl_stid.sc_client->net, nfsd_net_id) != nn)
continue;
- if (time_after((unsigned long)dp->dl_time, (unsigned long)cutoff)) {
- t = dp->dl_time - cutoff;
+ t = dp->dl_time;
+ if (time_after((unsigned long)t, (unsigned long)cutoff)) {
+ t -= cutoff;
new_timeo = min(new_timeo, t);
break;
}
diff --git a/fs/nfsd/state.h b/fs/nfsd/state.h
index 374c66283ac5..eae4fcaa5fd4 100644
--- a/fs/nfsd/state.h
+++ b/fs/nfsd/state.h
@@ -382,6 +382,7 @@ static inline struct nfs4_lockowner * lockowner(struct nfs4_stateowner *so)
/* nfs4_file: a file opened by some number of (open) nfs4_stateowners. */
struct nfs4_file {
atomic_t fi_ref;
+ spinlock_t fi_lock;
struct hlist_node fi_hash; /* hash by "struct inode *" */
struct list_head fi_stateids;
struct list_head fi_delegations;
@@ -472,6 +473,7 @@ extern void nfsd4_cb_recall(struct nfs4_delegation *dp);
extern int nfsd4_create_callback_queue(void);
extern void nfsd4_destroy_callback_queue(void);
extern void nfsd4_shutdown_callback(struct nfs4_client *);
+extern void nfsd4_queue_to_del_recall_lru(struct nfs4_delegation *);
extern void nfs4_put_delegation(struct nfs4_delegation *dp);
extern struct nfs4_client_reclaim *nfs4_client_to_reclaim(const char *name,
struct nfsd_net *nn);
--
1.9.3
--
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