NFSv4.1: Convert pNFS deviceid to use kfree_rcu()

Use of synchronize_rcu() when unmounting and potentially freeing a lot
of deviceids is problematic. There really is no reason why we can't just
use kfree_rcu() here.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

6 files changed, 7 insertions, 8 deletions

diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c
index 5aed4f98df41..e535599a0719 100644
--- a/fs/nfs/blocklayout/dev.c
+++ b/fs/nfs/blocklayout/dev.c
@@ -33,7 +33,7 @@ bl_free_deviceid_node(struct nfs4_deviceid_node *d)
                 container_of(d, struct pnfs_block_dev, node);
 
         bl_free_device(dev);
-        kfree(dev);
+        kfree_rcu(dev, node.rcu);
 }
 
 static int
diff --git a/fs/nfs/filelayout/filelayoutdev.c b/fs/nfs/filelayout/filelayoutdev.c
index 4f372e224603..4946ef40ba87 100644
--- a/fs/nfs/filelayout/filelayoutdev.c
+++ b/fs/nfs/filelayout/filelayoutdev.c
@@ -55,7 +55,7 @@ nfs4_fl_free_deviceid(struct nfs4_file_layout_dsaddr *dsaddr)
                         nfs4_pnfs_ds_put(ds);
         }
         kfree(dsaddr->stripe_indices);
-        kfree(dsaddr);
+        kfree_rcu(dsaddr, id_node.rcu);
 }
 
 /* Decode opaque device data and return the result */
diff --git a/fs/nfs/flexfilelayout/flexfilelayoutdev.c b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
index e2c01f204a95..77a2d026aa12 100644
--- a/fs/nfs/flexfilelayout/flexfilelayoutdev.c
+++ b/fs/nfs/flexfilelayout/flexfilelayoutdev.c
@@ -30,7 +30,7 @@ void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
 {
         nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
         nfs4_pnfs_ds_put(mirror_ds->ds);
-        kfree(mirror_ds);
+        kfree_rcu(mirror_ds, id_node.rcu);
 }
 
 /* Decode opaque device data and construct new_ds using it */
diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index 24e1d7403c0b..8b5e0e687d5e 100644
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -57,7 +57,7 @@ objio_free_deviceid_node(struct nfs4_deviceid_node *d)
 
         dprintk("%s: free od=%p\n", __func__, de->od.od);
         osduld_put_device(de->od.od);
-        kfree(de);
+        kfree_rcu(d, rcu);
 }
 
 struct objio_segment {
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 635f0865671c..a1fc16c971a7 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -302,6 +302,7 @@ struct nfs4_deviceid_node {
         unsigned long                   flags;
         unsigned long                   timestamp_unavailable;
         struct nfs4_deviceid            deviceid;
+        struct rcu_head                 rcu;
         atomic_t                        ref;
 };
 
diff --git a/fs/nfs/pnfs_dev.c b/fs/nfs/pnfs_dev.c
index aa2ec0015183..bf23ac97d57d 100644
--- a/fs/nfs/pnfs_dev.c
+++ b/fs/nfs/pnfs_dev.c
@@ -175,8 +175,8 @@ __nfs4_find_get_deviceid(struct nfs_server *server,
         rcu_read_lock();
         d = _lookup_deviceid(server->pnfs_curr_ld, server->nfs_client, id,
                         hash);
-        if (d != NULL)
-                atomic_inc(&d->ref);
+        if (d != NULL && !atomic_inc_not_zero(&d->ref))
+                d = NULL;
         rcu_read_unlock();
         return d;
 }
@@ -236,7 +236,6 @@ nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
         }
         hlist_del_init_rcu(&d->node);
         spin_unlock(&nfs4_deviceid_lock);
-        synchronize_rcu();
 
         /* balance the initial ref set in pnfs_insert_deviceid */
         if (atomic_dec_and_test(&d->ref))
@@ -321,7 +320,6 @@ _deviceid_purge_client(const struct nfs_client *clp, long hash)
         if (hlist_empty(&tmp))
                 return;
 
-        synchronize_rcu();
         while (!hlist_empty(&tmp)) {
                 d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
                 hlist_del(&d->tmpnode);