afs: Add some callback management tracepoints

Add a couple of tracepoints to track callback management:

 (1) afs_cb_miss - Logs when we were unable to apply a callback, either due
     to the inode being discarded or due to a competing thread applying a
     callback first.

 (2) afs_cb_break - Logs when we attempted to clear the noted callback
     promise, either due to the server explicitly breaking the callback,
     the callback promise lapsing or a local event obsoleting it.

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

1 files changed, 10 insertions, 7 deletions

diff --git a/fs/afs/inode.c b/fs/afs/inode.c
index 18a50d4febcf..7b1c18c32f48 100644
--- a/fs/afs/inode.c
+++ b/fs/afs/inode.c
@@ -283,7 +283,7 @@ void afs_vnode_commit_status(struct afs_fs_cursor *fc,
 		if (scb->status.abort_code == VNOVNODE) {
 			set_bit(AFS_VNODE_DELETED, &vnode->flags);
 			clear_nlink(&vnode->vfs_inode);
-			__afs_break_callback(vnode);
+			__afs_break_callback(vnode, afs_cb_break_for_deleted);
 		}
 	} else {
 		if (scb->have_status)
@@ -594,8 +594,9 @@ 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();
-	bool valid, need_clear = false;
+	bool valid;
 	unsigned int cb_break, cb_s_break, cb_v_break;
 	int seq = 0;
 
@@ -613,13 +614,13 @@ bool afs_check_validity(struct afs_vnode *vnode)
 			    vnode->cb_v_break != cb_v_break) {
 				vnode->cb_s_break = cb_s_break;
 				vnode->cb_v_break = cb_v_break;
-				need_clear = true;
+				need_clear = afs_cb_break_for_vsbreak;
 				valid = false;
 			} else if (test_bit(AFS_VNODE_ZAP_DATA, &vnode->flags)) {
-				need_clear = true;
+				need_clear = afs_cb_break_for_zap;
 				valid = false;
 			} else if (vnode->cb_expires_at - 10 <= now) {
-				need_clear = true;
+				need_clear = afs_cb_break_for_lapsed;
 				valid = false;
 			} else {
 				valid = true;
@@ -635,10 +636,12 @@ bool afs_check_validity(struct afs_vnode *vnode)
 
 	done_seqretry(&vnode->cb_lock, seq);
 
-	if (need_clear) {
+	if (need_clear != afs_cb_break_no_break) {
 		write_seqlock(&vnode->cb_lock);
 		if (cb_break == vnode->cb_break)
-			__afs_break_callback(vnode);
+			__afs_break_callback(vnode, need_clear);
+		else
+			trace_afs_cb_miss(&vnode->fid, need_clear);
 		write_sequnlock(&vnode->cb_lock);
 		valid = false;
 	}