afs: Reorganise volume and server trees to be rooted on the cell

Reorganise afs_volume objects such that they're in a tree keyed on volume
ID, rooted at on an afs_cell object rather than being in multiple trees,
each of which is rooted on an afs_server object.

afs_server structs become per-cell and acquire a pointer to the cell.

The process of breaking a callback then starts with finding the server by
its network address, following that to the cell and then looking up each
volume ID in the volume tree.

This is simpler than the afs_vol_interest/afs_cb_interest N:M mapping web
and allows those structs and the code for maintaining them to be simplified
or removed.

It does make a couple of things a bit more tricky, though:

 (1) Operations now start with a volume, not a server, so there can be more
     than one answer as to whether or not the server we'll end up using
     supports the FS.InlineBulkStatus RPC.

 (2) CB RPC operations that specify the server UUID.  There's still a tree
     of servers by UUID on the afs_net struct, but the UUIDs in it aren't
     guaranteed unique.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 25 insertions, 34 deletions

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 94675acb6a3a..7dde703df40c 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -71,7 +71,6 @@ static int afs_inode_init_from_status(struct afs_operation *op,
 				      struct afs_vnode_param *vp,
 				      struct afs_vnode *vnode)
 {
-	struct afs_cb_interest *old_cbi = NULL;
 	struct afs_file_status *status = &vp->scb.status;
 	struct inode *inode = AFS_VNODE_TO_I(vnode);
 	struct timespec64 t;
@@ -150,18 +149,11 @@ static int afs_inode_init_from_status(struct afs_operation *op,
 		vnode->cb_expires_at = ktime_get_real_seconds();
 	} else {
 		vnode->cb_expires_at = vp->scb.callback.expires_at;
-		old_cbi = rcu_dereference_protected(vnode->cb_interest,
-						    lockdep_is_held(&vnode->cb_lock.lock));
-		if (op->cbi != old_cbi)
-			rcu_assign_pointer(vnode->cb_interest,
-					   afs_get_cb_interest(op->cbi));
-		else
-			old_cbi = NULL;
+		vnode->cb_server = op->server;
 		set_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
 	}
 
 	write_sequnlock(&vnode->cb_lock);
-	afs_put_cb_interest(afs_v2net(vnode), old_cbi);
 	return 0;
 }
 
@@ -255,18 +247,12 @@ static void afs_apply_status(struct afs_operation *op,
 static void afs_apply_callback(struct afs_operation *op,
 			       struct afs_vnode_param *vp)
 {
-	struct afs_cb_interest *old;
 	struct afs_callback *cb = &vp->scb.callback;
 	struct afs_vnode *vnode = vp->vnode;
 
-	if (!afs_cb_is_broken(vp->cb_break_before, vnode, op->cbi)) {
+	if (!afs_cb_is_broken(vp->cb_break_before, vnode)) {
 		vnode->cb_expires_at	= cb->expires_at;
-		old = rcu_dereference_protected(vnode->cb_interest,
-						lockdep_is_held(&vnode->cb_lock.lock));
-		if (old != op->cbi) {
-			rcu_assign_pointer(vnode->cb_interest, afs_get_cb_interest(op->cbi));
-			afs_put_cb_interest(afs_v2net(vnode), old);
-		}
+		vnode->cb_server	= op->server;
 		set_bit(AFS_VNODE_CB_PROMISED, &vnode->flags);
 	}
 }
@@ -570,12 +556,30 @@ void afs_zap_data(struct afs_vnode *vnode)
 }
 
 /*
+ * Get the server reinit counter for a vnode's current server.
+ */
+static bool afs_get_s_break_rcu(struct afs_vnode *vnode, unsigned int *_s_break)
+{
+	struct afs_server_list *slist = rcu_dereference(vnode->volume->servers);
+	struct afs_server *server;
+	int i;
+
+	for (i = 0; i < slist->nr_servers; i++) {
+		server = slist->servers[i].server;
+		if (server == vnode->cb_server) {
+			*_s_break = READ_ONCE(server->cb_s_break);
+			return true;
+		}
+	}
+
+	return false;
+}
+
+/*
  * Check the validity of a vnode/inode.
  */
 bool afs_check_validity(struct afs_vnode *vnode)
 {
-	struct afs_cb_interest *cbi;
-	struct afs_server *server;
 	struct afs_volume *volume = vnode->volume;
 	enum afs_cb_break_reason need_clear = afs_cb_break_no_break;
 	time64_t now = ktime_get_real_seconds();
@@ -588,11 +592,8 @@ bool afs_check_validity(struct afs_vnode *vnode)
 		cb_v_break = READ_ONCE(volume->cb_v_break);
 		cb_break = vnode->cb_break;
 
-		if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags)) {
-			cbi = rcu_dereference(vnode->cb_interest);
-			server = rcu_dereference(cbi->server);
-			cb_s_break = READ_ONCE(server->cb_s_break);
-
+		if (test_bit(AFS_VNODE_CB_PROMISED, &vnode->flags) &&
+		    afs_get_s_break_rcu(vnode, &cb_s_break)) {
 			if (vnode->cb_s_break != cb_s_break ||
 			    vnode->cb_v_break != cb_v_break) {
 				vnode->cb_s_break = cb_s_break;
@@ -739,7 +740,6 @@ int afs_drop_inode(struct inode *inode)
  */
 void afs_evict_inode(struct inode *inode)
 {
-	struct afs_cb_interest *cbi;
 	struct afs_vnode *vnode;
 
 	vnode = AFS_FS_I(inode);
@@ -756,15 +756,6 @@ void afs_evict_inode(struct inode *inode)
 	truncate_inode_pages_final(&inode->i_data);
 	clear_inode(inode);
 
-	write_seqlock(&vnode->cb_lock);
-	cbi = rcu_dereference_protected(vnode->cb_interest,
-					lockdep_is_held(&vnode->cb_lock.lock));
-	if (cbi) {
-		afs_put_cb_interest(afs_i2net(inode), cbi);
-		rcu_assign_pointer(vnode->cb_interest, NULL);
-	}
-	write_sequnlock(&vnode->cb_lock);
-
 	while (!list_empty(&vnode->wb_keys)) {
 		struct afs_wb_key *wbk = list_entry(vnode->wb_keys.next,
 						    struct afs_wb_key, vnode_link);