nfsd: give block_delegation and delegation_blocked its own spinlock

The state lock can be fairly heavily contended, and there's no reason
that nfs4_file lookups and delegation_blocked should be mutually
exclusive.  Let's give the new block_delegation code its own spinlock.
It does mean that we'll need to take a different lock in the delegation
break code, but that's not generally as critical to performance.

Cc: Neil Brown <neilb@suse.de>
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 85d7ac6..ecfddca 100644 (file)
--- a/fs/nfsd/nfs4state.c
+++ b/fs/nfsd/nfs4state.c
@@ -517,10 +517,11 @@ static struct nfs4_ol_stateid * nfs4_alloc_stateid(struct nfs4_client *clp)
  * Each filter is 256 bits.  We hash the filehandle to 32bit and use the
  * low 3 bytes as hash-table indices.
  *
- * 'state_lock', which is always held when block_delegations() is called,
+ * 'blocked_delegations_lock', which is always taken in block_delegations(),
  * is used to manage concurrent access.  Testing does not need the lock
  * except when swapping the two filters.
  */
+static DEFINE_SPINLOCK(blocked_delegations_lock);
 static struct bloom_pair {
        int     entries, old_entries;
        time_t  swap_time;
@@ -536,7 +537,7 @@ static int delegation_blocked(struct knfsd_fh *fh)
        if (bd->entries == 0)
                return 0;
        if (seconds_since_boot() - bd->swap_time > 30) {
-               spin_lock(&state_lock);
+               spin_lock(&blocked_delegations_lock);
                if (seconds_since_boot() - bd->swap_time > 30) {
                        bd->entries -= bd->old_entries;
                        bd->old_entries = bd->entries;
@@ -545,7 +546,7 @@ static int delegation_blocked(struct knfsd_fh *fh)
                        bd->new = 1-bd->new;
                        bd->swap_time = seconds_since_boot();
                }
-               spin_unlock(&state_lock);
+               spin_unlock(&blocked_delegations_lock);
        }
        hash = arch_fast_hash(&fh->fh_base, fh->fh_size, 0);
        if (test_bit(hash&255, bd->set[0]) &&
@@ -566,16 +567,16 @@ static void block_delegations(struct knfsd_fh *fh)
        u32 hash;
        struct bloom_pair *bd = &blocked_delegations;
 
-       lockdep_assert_held(&state_lock);
-
        hash = arch_fast_hash(&fh->fh_base, fh->fh_size, 0);
 
+       spin_lock(&blocked_delegations_lock);
        __set_bit(hash&255, bd->set[bd->new]);
        __set_bit((hash>>8)&255, bd->set[bd->new]);
        __set_bit((hash>>16)&255, bd->set[bd->new]);
        if (bd->entries == 0)
                bd->swap_time = seconds_since_boot();
        bd->entries += 1;
+       spin_unlock(&blocked_delegations_lock);
 }
 
 static struct nfs4_delegation *
@@ -3096,16 +3097,16 @@ 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);
 
-       /*
-        * 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);
+
        /*
+        * We can't do this in nfsd_break_deleg_cb because it is
+        * already holding inode->i_lock.
+        *
         * If the dl_time != 0, then we know that it has already been
         * queued for a lease break. Don't queue it again.
         */
+       spin_lock(&state_lock);
        if (dp->dl_time == 0) {
                dp->dl_time = get_seconds();
                list_add_tail(&dp->dl_recall_lru, &nn->del_recall_lru);