afs: Fix cleanup of immediately failed async calls

JIRA: https://issues.redhat.com/browse/RHEL-78388

commit 9750be9
Author: David Howells <dhowells@redhat.com>
Date:   Mon Dec 16 20:41:14 2024 +0000

    afs: Fix cleanup of immediately failed async calls

    If we manage to begin an async call, but fail to transmit any data on it
    due to a signal, we then abort it which causes a race between the
    notification of call completion from rxrpc and our attempt to cancel the
    notification.  The notification will be necessary, however, for async
    FetchData to terminate the netfs subrequest.

    However, since we get a notification from rxrpc upon completion of a call
    (aborted or otherwise), we can just leave it to that.

    This leads to calls not getting cleaned up, but appearing in
    /proc/net/rxrpc/calls as being aborted with code 6.

    Fix this by making the "error_do_abort:" case of afs_make_call() abort the
    call and then abandon it to the notification handler.

    Fixes: 34fa476 ("afs: Fix race in async call refcounting")
    Reported-by: Marc Dionne <marc.dionne@auristor.com>
    Signed-off-by: David Howells <dhowells@redhat.com>
    Link: https://lore.kernel.org/r/20241216204124.3752367-25-dhowells@redhat.com
    cc: linux-afs@lists.infradead.org
    Signed-off-by: Christian Brauner <brauner@kernel.org>

Signed-off-by: Marc Dionne <mdionne@redhat.com>

Author: mdionne

fs/afs/internal.h

@@ -1346,6 +1346,15 @@ extern void afs_send_simple_reply(struct afs_call *, const void *, size_t);
 extern int afs_extract_data(struct afs_call *, bool);
 extern int afs_protocol_error(struct afs_call *, enum afs_eproto_cause);
 
+static inline void afs_see_call(struct afs_call *call, enum afs_call_trace why)
+{
+	int r = refcount_read(&call->ref);
+
+	trace_afs_call(call->debug_id, why, r,
+		       atomic_read(&call->net->nr_outstanding_calls),
+		       __builtin_return_address(0));
+}
+
 static inline void afs_make_op_call(struct afs_operation *op, struct afs_call *call,
 				    gfp_t gfp)
 {

fs/afs/rxrpc.c

@@ -430,11 +430,16 @@ void afs_make_call(struct afs_call *call, gfp_t gfp)
 	return;
 
 error_do_abort:
-	if (ret != -ECONNABORTED) {
+	if (ret != -ECONNABORTED)
 		rxrpc_kernel_abort_call(call->net->socket, rxcall,
 					RX_USER_ABORT, ret,
 					afs_abort_send_data_error);
-	} else {
+	if (call->async) {
+		afs_see_call(call, afs_call_trace_async_abort);
+		return;
+	}
+
+	if (ret == -ECONNABORTED) {
 		len = 0;
 		iov_iter_kvec(&msg.msg_iter, ITER_DEST, NULL, 0, 0);
 		rxrpc_kernel_recv_data(call->net->socket, rxcall,
@@ -445,6 +450,8 @@ void afs_make_call(struct afs_call *call, gfp_t gfp)
 	call->error = ret;
 	trace_afs_call_done(call);
 error_kill_call:
+	if (call->async)
+		afs_see_call(call, afs_call_trace_async_kill);
 	if (call->type->done)
 		call->type->done(call);
 
@@ -602,7 +609,6 @@ static void afs_deliver_to_call(struct afs_call *call)
 	abort_code = 0;
 call_complete:
 	afs_set_call_complete(call, ret, remote_abort);
-	state = AFS_CALL_COMPLETE;
 	goto done;
 }
 

include/trace/events/afs.h

@@ -118,6 +118,8 @@ enum yfs_cm_operation {
  */
 #define afs_call_traces \
 	EM(afs_call_trace_alloc,		"ALLOC") \
+	EM(afs_call_trace_async_abort,		"ASYAB") \
+	EM(afs_call_trace_async_kill,		"ASYKL") \
 	EM(afs_call_trace_free,			"FREE ") \
 	EM(afs_call_trace_get,			"GET  ") \
 	EM(afs_call_trace_put,			"PUT  ") \