xref: /linux/fs/afs/server_list.c (revision 44f57d78) 
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* AFS fileserver list management.
3  *
4  * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/slab.h>
10 #include "internal.h"
11 
12 void afs_put_serverlist(struct afs_net *net, struct afs_server_list *slist)
13 {
14 	int i;
15 
16 	if (slist && refcount_dec_and_test(&slist->usage)) {
17 		for (i = 0; i < slist->nr_servers; i++) {
18 			afs_put_cb_interest(net, slist->servers[i].cb_interest);
19 			afs_put_server(net, slist->servers[i].server);
20 		}
21 		kfree(slist);
22 	}
23 }
24 
25 /*
26  * Build a server list from a VLDB record.
27  */
28 struct afs_server_list *afs_alloc_server_list(struct afs_cell *cell,
29 					      struct key *key,
30 					      struct afs_vldb_entry *vldb,
31 					      u8 type_mask)
32 {
33 	struct afs_server_list *slist;
34 	struct afs_server *server;
35 	int ret = -ENOMEM, nr_servers = 0, i, j;
36 
37 	for (i = 0; i < vldb->nr_servers; i++)
38 		if (vldb->fs_mask[i] & type_mask)
39 			nr_servers++;
40 
41 	slist = kzalloc(struct_size(slist, servers, nr_servers), GFP_KERNEL);
42 	if (!slist)
43 		goto error;
44 
45 	refcount_set(&slist->usage, 1);
46 	rwlock_init(&slist->lock);
47 
48 	/* Make sure a records exists for each server in the list. */
49 	for (i = 0; i < vldb->nr_servers; i++) {
50 		if (!(vldb->fs_mask[i] & type_mask))
51 			continue;
52 
53 		server = afs_lookup_server(cell, key, &vldb->fs_server[i]);
54 		if (IS_ERR(server)) {
55 			ret = PTR_ERR(server);
56 			if (ret == -ENOENT ||
57 			    ret == -ENOMEDIUM)
58 				continue;
59 			goto error_2;
60 		}
61 
62 		/* Insertion-sort by UUID */
63 		for (j = 0; j < slist->nr_servers; j++)
64 			if (memcmp(&slist->servers[j].server->uuid,
65 				   &server->uuid,
66 				   sizeof(server->uuid)) >= 0)
67 				break;
68 		if (j < slist->nr_servers) {
69 			if (slist->servers[j].server == server) {
70 				afs_put_server(cell->net, server);
71 				continue;
72 			}
73 
74 			memmove(slist->servers + j + 1,
75 				slist->servers + j,
76 				(slist->nr_servers - j) * sizeof(struct afs_server_entry));
77 		}
78 
79 		slist->servers[j].server = server;
80 		slist->nr_servers++;
81 	}
82 
83 	if (slist->nr_servers == 0) {
84 		ret = -EDESTADDRREQ;
85 		goto error_2;
86 	}
87 
88 	return slist;
89 
90 error_2:
91 	afs_put_serverlist(cell->net, slist);
92 error:
93 	return ERR_PTR(ret);
94 }
95 
96 /*
97  * Copy the annotations from an old server list to its potential replacement.
98  */
99 bool afs_annotate_server_list(struct afs_server_list *new,
100 			      struct afs_server_list *old)
101 {
102 	struct afs_server *cur;
103 	int i, j;
104 
105 	if (old->nr_servers != new->nr_servers)
106 		goto changed;
107 
108 	for (i = 0; i < old->nr_servers; i++)
109 		if (old->servers[i].server != new->servers[i].server)
110 			goto changed;
111 
112 	return false;
113 
114 changed:
115 	/* Maintain the same preferred server as before if possible. */
116 	cur = old->servers[old->preferred].server;
117 	for (j = 0; j < new->nr_servers; j++) {
118 		if (new->servers[j].server == cur) {
119 			new->preferred = j;
120 			break;
121 		}
122 	}
123 
124 	/* Keep the old callback interest records where possible so that we
125 	 * maintain callback interception.
126 	 */
127 	i = 0;
128 	j = 0;
129 	while (i < old->nr_servers && j < new->nr_servers) {
130 		if (new->servers[j].server == old->servers[i].server) {
131 			struct afs_cb_interest *cbi = old->servers[i].cb_interest;
132 			if (cbi) {
133 				new->servers[j].cb_interest = cbi;
134 				refcount_inc(&cbi->usage);
135 			}
136 			i++;
137 			j++;
138 			continue;
139 		}
140 
141 		if (new->servers[j].server < old->servers[i].server) {
142 			j++;
143 			continue;
144 		}
145 
146 		i++;
147 		continue;
148 	}
149 
150 	return true;
151 }
152