nfsd: Avoid taking state_lock while holding inode lock in nfsd_break_one_deleg
state_lock is a heavily contended global lock. We don't want to grab
that while simultaneously holding the inode->i_lock.
Add a new per-nfs4_file lock that we can use to protect the
per-nfs4_file delegation list. Hold that while walking the list in the
break_deleg callback and queue the workqueue job for each one.
The workqueue job can then take the state_lock and do the list
manipulations without the i_lock being held prior to starting the
rpc call.
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@primarydata.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
index 56ea4f1..bdf8ac3 100644
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -254,6 +254,8 @@
static inline void
put_nfs4_file(struct nfs4_file *fi)
{
+ might_lock(&state_lock);
+
if (atomic_dec_and_lock(&fi->fi_ref, &state_lock)) {
hlist_del(&fi->fi_hash);
spin_unlock(&state_lock);
@@ -554,6 +556,8 @@
u32 hash;
struct bloom_pair *bd = &blocked_delegations;
+ lockdep_assert_held(&state_lock);
+
hash = arch_fast_hash(&fh->fh_base, fh->fh_size, 0);
__set_bit(hash&255, bd->set[bd->new]);
@@ -592,7 +596,7 @@
fh_copy_shallow(&dp->dl_fh, ¤t_fh->fh_handle);
dp->dl_time = 0;
atomic_set(&dp->dl_count, 1);
- INIT_WORK(&dp->dl_recall.cb_work, nfsd4_do_callback_rpc);
+ INIT_WORK(&dp->dl_recall.cb_work, nfsd4_run_cb_recall);
return dp;
}
@@ -640,7 +644,9 @@
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);
}
@@ -648,14 +654,18 @@
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);
+ 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;
}
}
@@ -1677,7 +1687,7 @@
spin_unlock(&nn->client_lock);
return NULL;
}
- INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_do_callback_rpc);
+ INIT_WORK(&clp->cl_cb_null.cb_work, nfsd4_run_cb_null);
clp->cl_time = get_seconds();
clear_bit(0, &clp->cl_cb_slot_busy);
copy_verf(clp, verf);
@@ -3079,30 +3089,38 @@
return ret;
}
-static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
+void nfsd4_prepare_cb_recall(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(&state_lock);
- /* 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: */
- atomic_inc(&dp->dl_count);
-
+ /*
+ * We can't do this in nfsd_break_deleg_cb because it is
+ * already holding inode->i_lock
+ */
+ spin_lock(&state_lock);
+ block_delegations(&dp->dl_fh);
/*
* If the dl_time != 0, then we know that it has already been
* queued for a lease break. Don't queue it again.
*/
if (dp->dl_time == 0) {
- list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
dp->dl_time = get_seconds();
+ list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);
}
+ spin_unlock(&state_lock);
+}
- block_delegations(&dp->dl_fh);
-
+static void nfsd_break_one_deleg(struct nfs4_delegation *dp)
+{
+ /*
+ * 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.
+ */
+ atomic_inc(&dp->dl_count);
nfsd4_cb_recall(dp);
}
@@ -3127,11 +3145,11 @@
*/
fl->fl_break_time = 0;
- spin_lock(&state_lock);
fp->fi_had_conflict = true;
+ spin_lock(&fp->fi_lock);
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