AFS fixes

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Merge tag 'afs-fixes-20191211' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull AFS fixes from David Howells:
 "Fixes for AFS plus one patch to make debugging easier:

   - Fix how addresses are matched to server records. This is currently
     incorrect which means cache invalidation callbacks from the server
     don't necessarily get delivered correctly. This causes stale data
     and metadata to be seen under some circumstances.

   - Make the dynamic root superblock R/W so that rpm/dnf can reapply
     the SELinux label to it when upgrading the Fedora filesystem-afs
     package. If the filesystem is R/O, this fails and the upgrade
     fails.

     It might be better in future to allow setxattr from an LSM to
     bypass the R/O protections, if only for pseudo-filesystems.

   - Fix the parsing of mountpoint strings. The mountpoint object has to
     have a terminal dot, whereas the source/device string passed to
     mount should not. This confuses type-forcing suffix detection
     leading to the wrong volume variant being mounted.

   - Make lookups in the dynamic root superblock for creation events
     (such as mkdir) fail with EOPNOTSUPP rather than something like
     EEXIST. The dynamic root only allows implicit creation by the
     ->lookup() method - and only if the target cell exists.

   - Fix the looking up of an AFS superblock to include the cell in the
     matching key - otherwise all volumes with the same ID number are
     treated as the same thing, irrespective of which cell they're in.

   - Show the volume name of each volume in the volume records displayed
     in /proc/net/afs/<cell>/volumes. This proved useful in debugging as
     it provides a way to map the volume IDs to names, where the names
     are what appear in /proc/mounts"

* tag 'afs-fixes-20191211' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  afs: Show volume name in /proc/net/afs/<cell>/volumes
  afs: Fix missing cell comparison in afs_test_super()
  afs: Fix creation calls in the dynamic root to fail with EOPNOTSUPP
  afs: Fix mountpoint parsing
  afs: Fix SELinux setting security label on /afs
  afs: Fix afs_find_server lookups for ipv4 peers

fs/afs/dynroot.c

@@ -136,6 +136,9 @@ static struct dentry *afs_dynroot_lookup(struct inode *dir, struct dentry *dentr
 
 	ASSERTCMP(d_inode(dentry), ==, NULL);
 
+	if (flags & LOOKUP_CREATE)
+		return ERR_PTR(-EOPNOTSUPP);
+
 	if (dentry->d_name.len >= AFSNAMEMAX) {
 		_leave(" = -ENAMETOOLONG");
 		return ERR_PTR(-ENAMETOOLONG);

fs/afs/mntpt.c

@@ -126,7 +126,7 @@ static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
 		if (src_as->cell)
 			ctx->cell = afs_get_cell(src_as->cell);
 
-		if (size > PAGE_SIZE - 1)
+		if (size < 2 || size > PAGE_SIZE - 1)
 			return -EINVAL;
 
 		page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL);
@@ -140,7 +140,9 @@ static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt)
 		}
 
 		buf = kmap(page);
-		ret = vfs_parse_fs_string(fc, "source", buf, size);
+		ret = -EINVAL;
+		if (buf[size - 1] == '.')
+			ret = vfs_parse_fs_string(fc, "source", buf, size - 1);
 		kunmap(page);
 		put_page(page);
 		if (ret < 0)

fs/afs/proc.c

@@ -213,13 +213,14 @@ static int afs_proc_cell_volumes_show(struct seq_file *m, void *v)
 
 	/* Display header on line 1 */
 	if (v == &cell->proc_volumes) {
-		seq_puts(m, "USE VID      TY\n");
+		seq_puts(m, "USE VID      TY NAME\n");
 		return 0;
 	}
 
-	seq_printf(m, "%3d %08llx %s\n",
+	seq_printf(m, "%3d %08llx %s %s\n",
 		   atomic_read(&vol->usage), vol->vid,
-		   afs_vol_types[vol->type]);
+		   afs_vol_types[vol->type],
+		   vol->name);
 
 	return 0;
 }

fs/afs/server.c

@@ -32,18 +32,11 @@ static void afs_dec_servers_outstanding(struct afs_net *net)
 struct afs_server *afs_find_server(struct afs_net *net,
 				   const struct sockaddr_rxrpc *srx)
 {
-	const struct sockaddr_in6 *a = &srx->transport.sin6, *b;
 	const struct afs_addr_list *alist;
 	struct afs_server *server = NULL;
 	unsigned int i;
-	bool ipv6 = true;
 	int seq = 0, diff;
 
-	if (srx->transport.sin6.sin6_addr.s6_addr32[0] == 0 ||
-	    srx->transport.sin6.sin6_addr.s6_addr32[1] == 0 ||
-	    srx->transport.sin6.sin6_addr.s6_addr32[2] == htonl(0xffff))
-		ipv6 = false;
-
 	rcu_read_lock();
 
 	do {
@@ -52,7 +45,8 @@ struct afs_server *afs_find_server(struct afs_net *net,
 		server = NULL;
 		read_seqbegin_or_lock(&net->fs_addr_lock, &seq);
 
-		if (ipv6) {
+		if (srx->transport.family == AF_INET6) {
+			const struct sockaddr_in6 *a = &srx->transport.sin6, *b;
 			hlist_for_each_entry_rcu(server, &net->fs_addresses6, addr6_link) {
 				alist = rcu_dereference(server->addresses);
 				for (i = alist->nr_ipv4; i < alist->nr_addrs; i++) {
@@ -68,15 +62,16 @@ struct afs_server *afs_find_server(struct afs_net *net,
 				}
 			}
 		} else {
+			const struct sockaddr_in *a = &srx->transport.sin, *b;
 			hlist_for_each_entry_rcu(server, &net->fs_addresses4, addr4_link) {
 				alist = rcu_dereference(server->addresses);
 				for (i = 0; i < alist->nr_ipv4; i++) {
-					b = &alist->addrs[i].transport.sin6;
-					diff = ((u16 __force)a->sin6_port -
-						(u16 __force)b->sin6_port);
+					b = &alist->addrs[i].transport.sin;
+					diff = ((u16 __force)a->sin_port -
+						(u16 __force)b->sin_port);
 					if (diff == 0)
-						diff = ((u32 __force)a->sin6_addr.s6_addr32[3] -
-							(u32 __force)b->sin6_addr.s6_addr32[3]);
+						diff = ((u32 __force)a->sin_addr.s_addr -
+							(u32 __force)b->sin_addr.s_addr);
 					if (diff == 0)
 						goto found;
 				}

fs/afs/super.c

@@ -404,6 +404,7 @@ static int afs_test_super(struct super_block *sb, struct fs_context *fc)
 	return (as->net_ns == fc->net_ns &&
 		as->volume &&
 		as->volume->vid == ctx->volume->vid &&
+		as->cell == ctx->cell &&
 		!as->dyn_root);
 }
 
@@ -448,7 +449,6 @@ static int afs_fill_super(struct super_block *sb, struct afs_fs_context *ctx)
 	/* allocate the root inode and dentry */
 	if (as->dyn_root) {
 		inode = afs_iget_pseudo_dir(sb, true);
-		sb->s_flags	|= SB_RDONLY;
 	} else {
 		sprintf(sb->s_id, "%llu", as->volume->vid);
 		afs_activate_volume(as->volume);