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481 lines
10 KiB
481 lines
10 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* linux/fs/nfs/dns_resolve.c |
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* |
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* Copyright (c) 2009 Trond Myklebust <[email protected]> |
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* |
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* Resolves DNS hostnames into valid ip addresses |
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*/ |
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#ifdef CONFIG_NFS_USE_KERNEL_DNS |
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#include <linux/module.h> |
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#include <linux/sunrpc/clnt.h> |
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#include <linux/sunrpc/addr.h> |
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#include <linux/dns_resolver.h> |
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#include "dns_resolve.h" |
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ssize_t nfs_dns_resolve_name(struct net *net, char *name, size_t namelen, |
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struct sockaddr *sa, size_t salen) |
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{ |
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ssize_t ret; |
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char *ip_addr = NULL; |
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int ip_len; |
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ip_len = dns_query(net, NULL, name, namelen, NULL, &ip_addr, NULL, |
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false); |
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if (ip_len > 0) |
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ret = rpc_pton(net, ip_addr, ip_len, sa, salen); |
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else |
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ret = -ESRCH; |
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kfree(ip_addr); |
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return ret; |
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} |
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#else |
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#include <linux/module.h> |
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#include <linux/hash.h> |
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#include <linux/string.h> |
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#include <linux/kmod.h> |
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#include <linux/slab.h> |
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#include <linux/socket.h> |
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#include <linux/seq_file.h> |
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#include <linux/inet.h> |
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#include <linux/sunrpc/clnt.h> |
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#include <linux/sunrpc/addr.h> |
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#include <linux/sunrpc/cache.h> |
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#include <linux/sunrpc/svcauth.h> |
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#include <linux/sunrpc/rpc_pipe_fs.h> |
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#include <linux/nfs_fs.h> |
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#include "nfs4_fs.h" |
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#include "dns_resolve.h" |
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#include "cache_lib.h" |
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#include "netns.h" |
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#define NFS_DNS_HASHBITS 4 |
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#define NFS_DNS_HASHTBL_SIZE (1 << NFS_DNS_HASHBITS) |
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struct nfs_dns_ent { |
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struct cache_head h; |
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char *hostname; |
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size_t namelen; |
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struct sockaddr_storage addr; |
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size_t addrlen; |
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struct rcu_head rcu_head; |
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}; |
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static void nfs_dns_ent_update(struct cache_head *cnew, |
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struct cache_head *ckey) |
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{ |
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struct nfs_dns_ent *new; |
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struct nfs_dns_ent *key; |
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new = container_of(cnew, struct nfs_dns_ent, h); |
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key = container_of(ckey, struct nfs_dns_ent, h); |
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memcpy(&new->addr, &key->addr, key->addrlen); |
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new->addrlen = key->addrlen; |
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} |
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static void nfs_dns_ent_init(struct cache_head *cnew, |
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struct cache_head *ckey) |
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{ |
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struct nfs_dns_ent *new; |
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struct nfs_dns_ent *key; |
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new = container_of(cnew, struct nfs_dns_ent, h); |
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key = container_of(ckey, struct nfs_dns_ent, h); |
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kfree(new->hostname); |
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new->hostname = kmemdup_nul(key->hostname, key->namelen, GFP_KERNEL); |
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if (new->hostname) { |
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new->namelen = key->namelen; |
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nfs_dns_ent_update(cnew, ckey); |
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} else { |
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new->namelen = 0; |
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new->addrlen = 0; |
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} |
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} |
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static void nfs_dns_ent_free_rcu(struct rcu_head *head) |
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{ |
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struct nfs_dns_ent *item; |
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item = container_of(head, struct nfs_dns_ent, rcu_head); |
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kfree(item->hostname); |
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kfree(item); |
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} |
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static void nfs_dns_ent_put(struct kref *ref) |
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{ |
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struct nfs_dns_ent *item; |
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item = container_of(ref, struct nfs_dns_ent, h.ref); |
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call_rcu(&item->rcu_head, nfs_dns_ent_free_rcu); |
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} |
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static struct cache_head *nfs_dns_ent_alloc(void) |
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{ |
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struct nfs_dns_ent *item = kmalloc(sizeof(*item), GFP_KERNEL); |
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if (item != NULL) { |
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item->hostname = NULL; |
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item->namelen = 0; |
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item->addrlen = 0; |
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return &item->h; |
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} |
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return NULL; |
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}; |
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static unsigned int nfs_dns_hash(const struct nfs_dns_ent *key) |
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{ |
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return hash_str(key->hostname, NFS_DNS_HASHBITS); |
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} |
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static void nfs_dns_request(struct cache_detail *cd, |
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struct cache_head *ch, |
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char **bpp, int *blen) |
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{ |
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struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); |
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qword_add(bpp, blen, key->hostname); |
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(*bpp)[-1] = '\n'; |
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} |
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static int nfs_dns_upcall(struct cache_detail *cd, |
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struct cache_head *ch) |
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{ |
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struct nfs_dns_ent *key = container_of(ch, struct nfs_dns_ent, h); |
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if (test_and_set_bit(CACHE_PENDING, &ch->flags)) |
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return 0; |
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if (!nfs_cache_upcall(cd, key->hostname)) |
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return 0; |
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clear_bit(CACHE_PENDING, &ch->flags); |
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return sunrpc_cache_pipe_upcall_timeout(cd, ch); |
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} |
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static int nfs_dns_match(struct cache_head *ca, |
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struct cache_head *cb) |
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{ |
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struct nfs_dns_ent *a; |
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struct nfs_dns_ent *b; |
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a = container_of(ca, struct nfs_dns_ent, h); |
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b = container_of(cb, struct nfs_dns_ent, h); |
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if (a->namelen == 0 || a->namelen != b->namelen) |
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return 0; |
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return memcmp(a->hostname, b->hostname, a->namelen) == 0; |
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} |
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static int nfs_dns_show(struct seq_file *m, struct cache_detail *cd, |
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struct cache_head *h) |
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{ |
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struct nfs_dns_ent *item; |
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long ttl; |
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if (h == NULL) { |
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seq_puts(m, "# ip address hostname ttl\n"); |
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return 0; |
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} |
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item = container_of(h, struct nfs_dns_ent, h); |
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ttl = item->h.expiry_time - seconds_since_boot(); |
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if (ttl < 0) |
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ttl = 0; |
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if (!test_bit(CACHE_NEGATIVE, &h->flags)) { |
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char buf[INET6_ADDRSTRLEN+IPV6_SCOPE_ID_LEN+1]; |
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rpc_ntop((struct sockaddr *)&item->addr, buf, sizeof(buf)); |
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seq_printf(m, "%15s ", buf); |
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} else |
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seq_puts(m, "<none> "); |
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seq_printf(m, "%15s %ld\n", item->hostname, ttl); |
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return 0; |
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} |
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static struct nfs_dns_ent *nfs_dns_lookup(struct cache_detail *cd, |
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struct nfs_dns_ent *key) |
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{ |
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struct cache_head *ch; |
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ch = sunrpc_cache_lookup_rcu(cd, |
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&key->h, |
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nfs_dns_hash(key)); |
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if (!ch) |
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return NULL; |
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return container_of(ch, struct nfs_dns_ent, h); |
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} |
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static struct nfs_dns_ent *nfs_dns_update(struct cache_detail *cd, |
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struct nfs_dns_ent *new, |
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struct nfs_dns_ent *key) |
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{ |
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struct cache_head *ch; |
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ch = sunrpc_cache_update(cd, |
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&new->h, &key->h, |
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nfs_dns_hash(key)); |
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if (!ch) |
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return NULL; |
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return container_of(ch, struct nfs_dns_ent, h); |
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} |
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static int nfs_dns_parse(struct cache_detail *cd, char *buf, int buflen) |
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{ |
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char buf1[NFS_DNS_HOSTNAME_MAXLEN+1]; |
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struct nfs_dns_ent key, *item; |
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unsigned int ttl; |
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ssize_t len; |
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int ret = -EINVAL; |
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if (buf[buflen-1] != '\n') |
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goto out; |
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buf[buflen-1] = '\0'; |
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len = qword_get(&buf, buf1, sizeof(buf1)); |
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if (len <= 0) |
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goto out; |
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key.addrlen = rpc_pton(cd->net, buf1, len, |
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(struct sockaddr *)&key.addr, |
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sizeof(key.addr)); |
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len = qword_get(&buf, buf1, sizeof(buf1)); |
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if (len <= 0) |
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goto out; |
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key.hostname = buf1; |
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key.namelen = len; |
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memset(&key.h, 0, sizeof(key.h)); |
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if (get_uint(&buf, &ttl) < 0) |
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goto out; |
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if (ttl == 0) |
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goto out; |
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key.h.expiry_time = ttl + seconds_since_boot(); |
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ret = -ENOMEM; |
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item = nfs_dns_lookup(cd, &key); |
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if (item == NULL) |
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goto out; |
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if (key.addrlen == 0) |
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set_bit(CACHE_NEGATIVE, &key.h.flags); |
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item = nfs_dns_update(cd, &key, item); |
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if (item == NULL) |
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goto out; |
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ret = 0; |
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cache_put(&item->h, cd); |
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out: |
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return ret; |
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} |
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static int do_cache_lookup(struct cache_detail *cd, |
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struct nfs_dns_ent *key, |
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struct nfs_dns_ent **item, |
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struct nfs_cache_defer_req *dreq) |
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{ |
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int ret = -ENOMEM; |
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*item = nfs_dns_lookup(cd, key); |
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if (*item) { |
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ret = cache_check(cd, &(*item)->h, &dreq->req); |
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if (ret) |
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*item = NULL; |
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} |
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return ret; |
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} |
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static int do_cache_lookup_nowait(struct cache_detail *cd, |
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struct nfs_dns_ent *key, |
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struct nfs_dns_ent **item) |
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{ |
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int ret = -ENOMEM; |
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*item = nfs_dns_lookup(cd, key); |
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if (!*item) |
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goto out_err; |
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ret = -ETIMEDOUT; |
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if (!test_bit(CACHE_VALID, &(*item)->h.flags) |
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|| (*item)->h.expiry_time < seconds_since_boot() |
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|| cd->flush_time > (*item)->h.last_refresh) |
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goto out_put; |
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ret = -ENOENT; |
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if (test_bit(CACHE_NEGATIVE, &(*item)->h.flags)) |
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goto out_put; |
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return 0; |
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out_put: |
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cache_put(&(*item)->h, cd); |
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out_err: |
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*item = NULL; |
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return ret; |
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} |
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static int do_cache_lookup_wait(struct cache_detail *cd, |
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struct nfs_dns_ent *key, |
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struct nfs_dns_ent **item) |
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{ |
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struct nfs_cache_defer_req *dreq; |
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int ret = -ENOMEM; |
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dreq = nfs_cache_defer_req_alloc(); |
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if (!dreq) |
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goto out; |
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ret = do_cache_lookup(cd, key, item, dreq); |
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if (ret == -EAGAIN) { |
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ret = nfs_cache_wait_for_upcall(dreq); |
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if (!ret) |
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ret = do_cache_lookup_nowait(cd, key, item); |
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} |
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nfs_cache_defer_req_put(dreq); |
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out: |
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return ret; |
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} |
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ssize_t nfs_dns_resolve_name(struct net *net, char *name, |
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size_t namelen, struct sockaddr *sa, size_t salen) |
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{ |
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struct nfs_dns_ent key = { |
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.hostname = name, |
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.namelen = namelen, |
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}; |
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struct nfs_dns_ent *item = NULL; |
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ssize_t ret; |
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struct nfs_net *nn = net_generic(net, nfs_net_id); |
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ret = do_cache_lookup_wait(nn->nfs_dns_resolve, &key, &item); |
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if (ret == 0) { |
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if (salen >= item->addrlen) { |
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memcpy(sa, &item->addr, item->addrlen); |
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ret = item->addrlen; |
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} else |
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ret = -EOVERFLOW; |
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cache_put(&item->h, nn->nfs_dns_resolve); |
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} else if (ret == -ENOENT) |
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ret = -ESRCH; |
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return ret; |
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} |
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static struct cache_detail nfs_dns_resolve_template = { |
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.owner = THIS_MODULE, |
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.hash_size = NFS_DNS_HASHTBL_SIZE, |
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.name = "dns_resolve", |
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.cache_put = nfs_dns_ent_put, |
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.cache_upcall = nfs_dns_upcall, |
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.cache_request = nfs_dns_request, |
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.cache_parse = nfs_dns_parse, |
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.cache_show = nfs_dns_show, |
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.match = nfs_dns_match, |
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.init = nfs_dns_ent_init, |
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.update = nfs_dns_ent_update, |
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.alloc = nfs_dns_ent_alloc, |
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}; |
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int nfs_dns_resolver_cache_init(struct net *net) |
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{ |
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int err; |
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struct nfs_net *nn = net_generic(net, nfs_net_id); |
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nn->nfs_dns_resolve = cache_create_net(&nfs_dns_resolve_template, net); |
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if (IS_ERR(nn->nfs_dns_resolve)) |
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return PTR_ERR(nn->nfs_dns_resolve); |
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err = nfs_cache_register_net(net, nn->nfs_dns_resolve); |
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if (err) |
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goto err_reg; |
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return 0; |
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err_reg: |
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cache_destroy_net(nn->nfs_dns_resolve, net); |
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return err; |
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} |
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void nfs_dns_resolver_cache_destroy(struct net *net) |
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{ |
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struct nfs_net *nn = net_generic(net, nfs_net_id); |
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nfs_cache_unregister_net(net, nn->nfs_dns_resolve); |
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cache_destroy_net(nn->nfs_dns_resolve, net); |
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} |
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static int nfs4_dns_net_init(struct net *net) |
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{ |
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return nfs_dns_resolver_cache_init(net); |
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} |
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static void nfs4_dns_net_exit(struct net *net) |
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{ |
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nfs_dns_resolver_cache_destroy(net); |
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} |
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static struct pernet_operations nfs4_dns_resolver_ops = { |
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.init = nfs4_dns_net_init, |
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.exit = nfs4_dns_net_exit, |
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}; |
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static int rpc_pipefs_event(struct notifier_block *nb, unsigned long event, |
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void *ptr) |
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{ |
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struct super_block *sb = ptr; |
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struct net *net = sb->s_fs_info; |
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struct nfs_net *nn = net_generic(net, nfs_net_id); |
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struct cache_detail *cd = nn->nfs_dns_resolve; |
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int ret = 0; |
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if (cd == NULL) |
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return 0; |
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if (!try_module_get(THIS_MODULE)) |
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return 0; |
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switch (event) { |
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case RPC_PIPEFS_MOUNT: |
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ret = nfs_cache_register_sb(sb, cd); |
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break; |
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case RPC_PIPEFS_UMOUNT: |
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nfs_cache_unregister_sb(sb, cd); |
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break; |
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default: |
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ret = -ENOTSUPP; |
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break; |
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} |
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module_put(THIS_MODULE); |
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return ret; |
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} |
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static struct notifier_block nfs_dns_resolver_block = { |
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.notifier_call = rpc_pipefs_event, |
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}; |
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int nfs_dns_resolver_init(void) |
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{ |
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int err; |
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err = register_pernet_subsys(&nfs4_dns_resolver_ops); |
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if (err < 0) |
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goto out; |
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err = rpc_pipefs_notifier_register(&nfs_dns_resolver_block); |
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if (err < 0) |
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goto out1; |
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return 0; |
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out1: |
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unregister_pernet_subsys(&nfs4_dns_resolver_ops); |
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out: |
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return err; |
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} |
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void nfs_dns_resolver_destroy(void) |
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{ |
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rpc_pipefs_notifier_unregister(&nfs_dns_resolver_block); |
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unregister_pernet_subsys(&nfs4_dns_resolver_ops); |
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} |
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#endif
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