afs: Apply server breaks to mmap'd files in the call processor

Apply server breaks to mmap'd files that are being used from that server
from the call processor work function rather than punting it off to a
workqueue.  The work item, afs_server_init_callback(), then bumps each
individual inode off to its own work item introducing a potentially lengthy
delay.  This reduces that delay at the cost of extending the amount of time
we delay replying to the CB.InitCallBack3 notification RPC from the server.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org

1 files changed, 19 insertions, 14 deletions

diff --git a/fs/afs/callback.c b/fs/afs/callback.c
index 90f9b2a46ff4..f67e88076761 100644
--- a/fs/afs/callback.c
+++ b/fs/afs/callback.c
@@ -33,9 +33,8 @@ void afs_invalidate_mmap_work(struct work_struct *work)
 	unmap_mapping_pages(vnode->netfs.inode.i_mapping, 0, 0, false);
 }
 
-void afs_server_init_callback_work(struct work_struct *work)
+static void afs_server_init_callback(struct afs_server *server)
 {
-	struct afs_server *server = container_of(work, struct afs_server, initcb_work);
 	struct afs_vnode *vnode;
 	struct afs_cell *cell = server->cell;
 
@@ -57,15 +56,19 @@ void afs_server_init_callback_work(struct work_struct *work)
  */
 void afs_init_callback_state(struct afs_server *server)
 {
-	rcu_read_lock();
+	struct afs_cell *cell = server->cell;
+
+	down_read(&cell->vs_lock);
+
 	do {
 		server->cb_s_break++;
 		atomic_inc(&server->cell->fs_s_break);
 		if (!list_empty(&server->cell->fs_open_mmaps))
-			queue_work(system_unbound_wq, &server->initcb_work);
+			afs_server_init_callback(server);
 
 	} while ((server = rcu_dereference(server->uuid_next)));
-	rcu_read_unlock();
+
+	up_read(&cell->vs_lock);
 }
 
 /*
@@ -112,7 +115,7 @@ static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell,
 	struct rb_node *p;
 	int seq = 1;
 
-	do {
+	for (;;) {
 		/* Unfortunately, rbtree walking doesn't give reliable results
 		 * under just the RCU read lock, so we have to check for
 		 * changes.
@@ -133,7 +136,12 @@ static struct afs_volume *afs_lookup_volume_rcu(struct afs_cell *cell,
 			volume = NULL;
 		}
 
-	} while (need_seqretry(&cell->volume_lock, seq));
+		if (volume && afs_try_get_volume(volume, afs_volume_trace_get_callback))
+			break;
+		if (!need_seqretry(&cell->volume_lock, seq))
+			break;
+		seq |= 1; /* Want a lock next time */
+	}
 
 	done_seqretry(&cell->volume_lock, seq);
 	return volume;
@@ -188,12 +196,11 @@ static void afs_break_some_callbacks(struct afs_server *server,
 	afs_volid_t vid = cbb->fid.vid;
 	size_t i;
 
+	rcu_read_lock();
 	volume = afs_lookup_volume_rcu(server->cell, vid);
-
 	/* TODO: Find all matching volumes if we couldn't match the server and
 	 * break them anyway.
 	 */
-
 	for (i = *_count; i > 0; cbb++, i--) {
 		if (cbb->fid.vid == vid) {
 			_debug("- Fid { vl=%08llx n=%llu u=%u }",
@@ -207,6 +214,9 @@ static void afs_break_some_callbacks(struct afs_server *server,
 			*residue++ = *cbb;
 		}
 	}
+
+	rcu_read_unlock();
+	afs_put_volume(volume, afs_volume_trace_put_callback);
 }
 
 /*
@@ -219,11 +229,6 @@ void afs_break_callbacks(struct afs_server *server, size_t count,
 
 	ASSERT(server != NULL);
 
-	rcu_read_lock();
-
 	while (count > 0)
 		afs_break_some_callbacks(server, callbacks, &count);
-
-	rcu_read_unlock();
-	return;
 }