afs: Simplify error handling

Simplify error handling a bit by moving it from the afs_addr_cursor struct
to the afs_operation and afs_vl_cursor structs and using the error
prioritisation function for accumulating errors from multiple sources (AFS
tries to rotate between multiple fileservers, some of which may be
inaccessible or in some state of offlinedness).

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

fs/afs/addr_list.c

@@ -386,26 +386,24 @@ bool afs_iterate_addresses(struct afs_addr_cursor *ac)
 selected:
 	ac->index = index;
 	set_bit(index, &ac->tried);
-	ac->responded = false;
+	ac->call_responded = false;
 	return true;
 }
 
 /*
  * Release an address list cursor.
  */
-int afs_end_cursor(struct afs_addr_cursor *ac)
+void afs_end_cursor(struct afs_addr_cursor *ac)
 {
 	struct afs_addr_list *alist;
 
 	alist = ac->alist;
 	if (alist) {
-		if (ac->responded &&
+		if (ac->call_responded &&
 		    ac->index != alist->preferred &&
 		    test_bit(ac->alist->preferred, &ac->tried))
 			WRITE_ONCE(alist->preferred, ac->index);
 		afs_put_addrlist(alist);
 		ac->alist = NULL;
 	}
-
-	return ac->error;
 }

fs/afs/dir.c

@@ -693,8 +693,9 @@ static void afs_do_lookup_success(struct afs_operation *op)
 			vp = &op->file[0];
 			abort_code = vp->scb.status.abort_code;
 			if (abort_code != 0) {
-				op->ac.abort_code = abort_code;
-				op->error = afs_abort_to_error(abort_code);
+				op->call_abort_code = abort_code;
+				afs_op_set_error(op, afs_abort_to_error(abort_code));
+				op->cumul_error.abort_code = abort_code;
 			}
 			break;
 
@@ -846,13 +847,14 @@ static struct inode *afs_do_lookup(struct inode *dir, struct dentry *dentry,
 	_debug("nr_files %u", op->nr_files);
 
 	/* Need space for examining all the selected files */
-	op->error = -ENOMEM;
 	if (op->nr_files > 2) {
 		op->more_files = kvcalloc(op->nr_files - 2,
 					  sizeof(struct afs_vnode_param),
 					  GFP_KERNEL);
-		if (!op->more_files)
+		if (!op->more_files) {
+			afs_op_nomem(op);
 			goto out_op;
+		}
 
 		for (i = 2; i < op->nr_files; i++) {
 			vp = &op->more_files[i - 2];
@@ -1255,7 +1257,7 @@ void afs_check_for_remote_deletion(struct afs_operation *op)
 {
 	struct afs_vnode *vnode = op->file[0].vnode;
 
-	switch (op->ac.abort_code) {
+	switch (afs_op_abort_code(op)) {
 	case VNOVNODE:
 		set_bit(AFS_VNODE_DELETED, &vnode->flags);
 		afs_break_callback(vnode, afs_cb_break_for_deleted);
@@ -1280,7 +1282,7 @@ static void afs_vnode_new_inode(struct afs_operation *op)
 		/* ENOMEM or EINTR at a really inconvenient time - just abandon
 		 * the new directory on the server.
 		 */
-		op->error = PTR_ERR(inode);
+		afs_op_accumulate_error(op, PTR_ERR(inode), 0);
 		return;
 	}
 

fs/afs/dir_silly.c

@@ -218,7 +218,7 @@ static int afs_do_silly_unlink(struct afs_vnode *dvnode, struct afs_vnode *vnode
 	/* If there was a conflict with a third party, check the status of the
 	 * unlinked vnode.
 	 */
-	if (op->error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
+	if (op->cumul_error.error == 0 && (op->flags & AFS_OPERATION_DIR_CONFLICT)) {
 		op->file[1].update_ctime = false;
 		op->fetch_status.which = 1;
 		op->ops = &afs_fetch_status_operation;

fs/afs/file.c

@@ -245,10 +245,7 @@ static void afs_fetch_data_notify(struct afs_operation *op)
 	struct netfs_io_subrequest *subreq = req->subreq;
 	int error = afs_op_error(op);
 
-	if (error == -ECONNABORTED)
-		error = afs_abort_to_error(op->ac.abort_code);
 	req->error = error;
-
 	if (subreq) {
 		__set_bit(NETFS_SREQ_CLEAR_TAIL, &subreq->flags);
 		netfs_subreq_terminated(subreq, error ?: req->actual_len, false);

fs/afs/fs_operation.c

@@ -169,9 +169,6 @@ static void afs_end_vnode_operation(struct afs_operation *op)
 	}
 
 	afs_drop_io_locks(op);
-
-	if (op->error == -ECONNABORTED)
-		op->error = afs_abort_to_error(op->ac.abort_code);
 }
 
 /*
@@ -182,35 +179,38 @@ void afs_wait_for_operation(struct afs_operation *op)
 	_enter("");
 
 	while (afs_select_fileserver(op)) {
+		op->call_error = 0;
+		op->call_abort_code = 0;
 		op->cb_s_break = op->server->cb_s_break;
 		if (test_bit(AFS_SERVER_FL_IS_YFS, &op->server->flags) &&
 		    op->ops->issue_yfs_rpc)
 			op->ops->issue_yfs_rpc(op);
 		else if (op->ops->issue_afs_rpc)
 			op->ops->issue_afs_rpc(op);
 		else
-			op->ac.error = -ENOTSUPP;
+			op->call_error = -ENOTSUPP;
 
 		if (op->call) {
 			afs_wait_for_call_to_complete(op->call, &op->ac);
-			op->error = op->ac.error;
+			op->call_abort_code = op->call->abort_code;
+			op->call_error = op->call->error;
+			op->call_responded = op->call->responded;
+			op->ac.call_responded = true;
+			WRITE_ONCE(op->ac.alist->addrs[op->ac.index].last_error,
+				   op->call_error);
 			afs_put_call(op->call);
 		}
 	}
 
-	switch (op->error) {
-	case 0:
+	if (!afs_op_error(op)) {
 		_debug("success");
 		op->ops->success(op);
-		break;
-	case -ECONNABORTED:
+	} else if (op->cumul_error.aborted) {
 		if (op->ops->aborted)
 			op->ops->aborted(op);
-		fallthrough;
-	default:
+	} else {
 		if (op->ops->failed)
 			op->ops->failed(op);
-		break;
 	}
 
 	afs_end_vnode_operation(op);

fs/afs/fsclient.c

@@ -1629,6 +1629,7 @@ int afs_fs_give_up_all_callbacks(struct afs_net *net,
 	call->server = afs_use_server(server, afs_server_trace_give_up_cb);
 	afs_make_call(ac, call, GFP_NOFS);
 	afs_wait_for_call_to_complete(call, ac);
+	ret = call->error;
 	afs_put_call(call);
 	return ret;
 }

fs/afs/internal.h

@@ -75,6 +75,7 @@ enum afs_call_state {
 struct afs_address {
 	struct rxrpc_peer	*peer;
 	u16			service_id;
+	short			last_error;	/* Last error from this address */
 };
 
 /*
@@ -121,7 +122,6 @@ struct afs_call {
 	};
 	void			*buffer;	/* reply receive buffer */
 	union {
-		long			ret0;	/* Value to reply with instead of 0 */
 		struct afs_addr_list	*ret_alist;
 		struct afs_vldb_entry	*ret_vldb;
 		char			*ret_str;
@@ -145,6 +145,7 @@ struct afs_call {
 	bool			upgrade;	/* T to request service upgrade */
 	bool			intr;		/* T if interruptible */
 	bool			unmarshalling_error; /* T if an unmarshalling error occurred */
+	bool			responded;	/* Got a response from the call (may be abort) */
 	u16			service_id;	/* Actual service ID (after upgrade) */
 	unsigned int		debug_id;	/* Trace ID */
 	u32			operation_ID;	/* operation ID for an incoming call */
@@ -719,8 +720,10 @@ struct afs_permits {
  * Error prioritisation and accumulation.
  */
 struct afs_error {
-	short	error;			/* Accumulated error */
+	s32	abort_code;		/* Cumulative abort code */
+	short	error;			/* Cumulative error */
 	bool	responded;		/* T if server responded */
+	bool	aborted;		/* T if ->error is from an abort */
 };
 
 /*
@@ -730,10 +733,8 @@ struct afs_addr_cursor {
 	struct afs_addr_list	*alist;		/* Current address list (pins ref) */
 	unsigned long		tried;		/* Tried addresses */
 	signed char		index;		/* Current address */
-	bool			responded;	/* T if the current address responded */
 	unsigned short		nr_iterations;	/* Number of address iterations */
-	short			error;
-	u32			abort_code;
+	bool			call_responded;
 };
 
 /*
@@ -746,13 +747,16 @@ struct afs_vl_cursor {
 	struct afs_vlserver	*server;	/* Server on which this resides */
 	struct key		*key;		/* Key for the server */
 	unsigned long		untried;	/* Bitmask of untried servers */
+	struct afs_error	cumul_error;	/* Cumulative error */
+	s32			call_abort_code;
 	short			index;		/* Current server */
-	short			error;
+	short			call_error;	/* Error from single call */
 	unsigned short		flags;
 #define AFS_VL_CURSOR_STOP	0x0001		/* Set to cease iteration */
 #define AFS_VL_CURSOR_RETRY	0x0002		/* Set to do a retry */
 #define AFS_VL_CURSOR_RETRIED	0x0004		/* Set if started a retry */
-	unsigned short		nr_iterations;	/* Number of server iterations */
+	short			nr_iterations;	/* Number of server iterations */
+	bool			call_responded;	/* T if the current address responded */
 };
 
 /*
@@ -803,8 +807,10 @@ struct afs_operation {
 	struct dentry		*dentry_2;	/* Second dentry to be altered */
 	struct timespec64	mtime;		/* Modification time to record */
 	struct timespec64	ctime;		/* Change time to set */
+	struct afs_error	cumul_error;	/* Cumulative error */
 	short			nr_files;	/* Number of entries in file[], more_files */
-	short			error;
+	short			call_error;	/* Error from single call */
+	s32			call_abort_code; /* Abort code from single call */
 	unsigned int		debug_id;
 
 	unsigned int		cb_v_break;	/* Volume break counter before op */
@@ -860,6 +866,8 @@ struct afs_operation {
 	unsigned long		untried;	/* Bitmask of untried servers */
 	short			index;		/* Current server */
 	short			nr_iterations;	/* Number of server iterations */
+	bool			call_responded;	/* T if the current address responded */
+
 
 	unsigned int		flags;
 #define AFS_OPERATION_STOP		0x0001	/* Set to cease iteration */
@@ -976,7 +984,7 @@ bool afs_addr_list_same(const struct afs_addr_list *a,
 			const struct afs_addr_list *b);
 extern struct afs_vlserver_list *afs_dns_query(struct afs_cell *, time64_t *);
 extern bool afs_iterate_addresses(struct afs_addr_cursor *);
-extern int afs_end_cursor(struct afs_addr_cursor *);
+extern void afs_end_cursor(struct afs_addr_cursor *ac);
 
 extern int afs_merge_fs_addr4(struct afs_net *net, struct afs_addr_list *addr,
 			      __be32 xdr, u16 port);
@@ -1235,17 +1243,27 @@ extern void afs_prioritise_error(struct afs_error *, int, u32);
 
 static inline void afs_op_nomem(struct afs_operation *op)
 {
-	op->error = -ENOMEM;
+	op->cumul_error.error = -ENOMEM;
 }
 
 static inline int afs_op_error(const struct afs_operation *op)
 {
-	return op->error;
+	return op->cumul_error.error;
+}
+
+static inline s32 afs_op_abort_code(const struct afs_operation *op)
+{
+	return op->cumul_error.abort_code;
 }
 
 static inline int afs_op_set_error(struct afs_operation *op, int error)
 {
-	return op->error = error;
+	return op->cumul_error.error = error;
+}
+
+static inline void afs_op_accumulate_error(struct afs_operation *op, int error, s32 abort_code)
+{
+	afs_prioritise_error(&op->cumul_error, error, abort_code);
 }
 
 /*
@@ -1619,7 +1637,7 @@ static inline void afs_update_dentry_version(struct afs_operation *op,
 					     struct afs_vnode_param *dir_vp,
 					     struct dentry *dentry)
 {
-	if (!op->error)
+	if (!op->cumul_error.error)
 		dentry->d_fsdata =
 			(void *)(unsigned long)dir_vp->scb.status.data_version;
 }

fs/afs/misc.c

@@ -116,6 +116,8 @@ void afs_prioritise_error(struct afs_error *e, int error, u32 abort_code)
 {
 	switch (error) {
 	case 0:
+		e->aborted = false;
+		e->error = 0;
 		return;
 	default:
 		if (e->error == -ETIMEDOUT ||
@@ -161,12 +163,16 @@ void afs_prioritise_error(struct afs_error *e, int error, u32 abort_code)
 		if (e->responded)
 			return;
 		e->error = error;
+		e->aborted = false;
 		return;
 
 	case -ECONNABORTED:
-		error = afs_abort_to_error(abort_code);
-		fallthrough;
+		e->error = afs_abort_to_error(abort_code);
+		e->aborted = true;
+		e->responded = true;
+		return;
 	case -ENETRESET: /* Responded, but we seem to have changed address */
+		e->aborted = false;
 		e->responded = true;
 		e->error = error;
 		return;