super.c

linux 内核源代码

out_unrec_xprt:
	printk(KERN_INFO "NFS: unrecognized transport protocol\n");
	return 0;

out_unrec_sec:
	printk(KERN_INFO "NFS: unrecognized security flavor\n");
	return 0;

out_unknown:
	printk(KERN_INFO "NFS: unknown mount option: %s\n", p);
	return 0;
}

/*
 * Use the remote server's MOUNT service to request the NFS file handle
 * corresponding to the provided path.
 */
static int nfs_try_mount(struct nfs_parsed_mount_data *args,
			 struct nfs_fh *root_fh)
{
	struct sockaddr_in sin;
	int status;

	if (args->mount_server.version == 0) {
		if (args->flags & NFS_MOUNT_VER3)
			args->mount_server.version = NFS_MNT3_VERSION;
		else
			args->mount_server.version = NFS_MNT_VERSION;
	}

	/*
	 * Construct the mount server's address.
	 */
	if (args->mount_server.address.sin_addr.s_addr != INADDR_ANY)
		sin = args->mount_server.address;
	else
		sin = args->nfs_server.address;
	/*
	 * autobind will be used if mount_server.port == 0
	 */
	sin.sin_port = htons(args->mount_server.port);

	/*
	 * Now ask the mount server to map our export path
	 * to a file handle.
	 */
	status = nfs_mount((struct sockaddr *) &sin,
			   sizeof(sin),
			   args->nfs_server.hostname,
			   args->nfs_server.export_path,
			   args->mount_server.version,
			   args->mount_server.protocol,
			   root_fh);
	if (status == 0)
		return 0;

	dfprintk(MOUNT, "NFS: unable to mount server " NIPQUAD_FMT
			", error %d\n", NIPQUAD(sin.sin_addr.s_addr), status);
	return status;
}

/*
 * Validate the NFS2/NFS3 mount data
 * - fills in the mount root filehandle
 *
 * For option strings, user space handles the following behaviors:
 *
 * + DNS: mapping server host name to IP address ("addr=" option)
 *
 * + failure mode: how to behave if a mount request can't be handled
 *   immediately ("fg/bg" option)
 *
 * + retry: how often to retry a mount request ("retry=" option)
 *
 * + breaking back: trying proto=udp after proto=tcp, v2 after v3,
 *   mountproto=tcp after mountproto=udp, and so on
 *
 * XXX: as far as I can tell, changing the NFS program number is not
 *      supported in the NFS client.
 */
static int nfs_validate_mount_data(void *options,
				   struct nfs_parsed_mount_data *args,
				   struct nfs_fh *mntfh,
				   const char *dev_name)
{
	struct nfs_mount_data *data = (struct nfs_mount_data *)options;

	memset(args, 0, sizeof(*args));

	if (data == NULL)
		goto out_no_data;

	args->flags		= (NFS_MOUNT_VER3 | NFS_MOUNT_TCP);
	args->rsize		= NFS_MAX_FILE_IO_SIZE;
	args->wsize		= NFS_MAX_FILE_IO_SIZE;
	args->timeo		= 600;
	args->retrans		= 2;
	args->acregmin		= 3;
	args->acregmax		= 60;
	args->acdirmin		= 30;
	args->acdirmax		= 60;
	args->mount_server.protocol = XPRT_TRANSPORT_UDP;
	args->mount_server.program = NFS_MNT_PROGRAM;
	args->nfs_server.protocol = XPRT_TRANSPORT_TCP;
	args->nfs_server.program = NFS_PROGRAM;

	switch (data->version) {
	case 1:
		data->namlen = 0;
	case 2:
		data->bsize = 0;
	case 3:
		if (data->flags & NFS_MOUNT_VER3)
			goto out_no_v3;
		data->root.size = NFS2_FHSIZE;
		memcpy(data->root.data, data->old_root.data, NFS2_FHSIZE);
	case 4:
		if (data->flags & NFS_MOUNT_SECFLAVOUR)
			goto out_no_sec;
	case 5:
		memset(data->context, 0, sizeof(data->context));
	case 6:
		if (data->flags & NFS_MOUNT_VER3)
			mntfh->size = data->root.size;
		else
			mntfh->size = NFS2_FHSIZE;

		if (mntfh->size > sizeof(mntfh->data))
			goto out_invalid_fh;

		memcpy(mntfh->data, data->root.data, mntfh->size);
		if (mntfh->size < sizeof(mntfh->data))
			memset(mntfh->data + mntfh->size, 0,
			       sizeof(mntfh->data) - mntfh->size);

		if (!nfs_verify_server_address((struct sockaddr *) &data->addr))
			goto out_no_address;

		/*
		 * Translate to nfs_parsed_mount_data, which nfs_fill_super
		 * can deal with.
		 */
		args->flags		= data->flags;
		args->rsize		= data->rsize;
		args->wsize		= data->wsize;
		args->flags		= data->flags;
		args->timeo		= data->timeo;
		args->retrans		= data->retrans;
		args->acregmin		= data->acregmin;
		args->acregmax		= data->acregmax;
		args->acdirmin		= data->acdirmin;
		args->acdirmax		= data->acdirmax;
		args->nfs_server.address = data->addr;
		if (!(data->flags & NFS_MOUNT_TCP))
			args->nfs_server.protocol = XPRT_TRANSPORT_UDP;
		/* N.B. caller will free nfs_server.hostname in all cases */
		args->nfs_server.hostname = kstrdup(data->hostname, GFP_KERNEL);
		args->namlen		= data->namlen;
		args->bsize		= data->bsize;
		args->auth_flavors[0]	= data->pseudoflavor;
		break;
	default: {
		unsigned int len;
		char *c;
		int status;

		if (nfs_parse_mount_options((char *)options, args) == 0)
			return -EINVAL;

		if (!nfs_verify_server_address((struct sockaddr *)
						&args->nfs_server.address))
			goto out_no_address;

		c = strchr(dev_name, ':');
		if (c == NULL)
			return -EINVAL;
		len = c - dev_name;
		/* N.B. caller will free nfs_server.hostname in all cases */
		args->nfs_server.hostname = kstrndup(dev_name, len, GFP_KERNEL);

		c++;
		if (strlen(c) > NFS_MAXPATHLEN)
			return -ENAMETOOLONG;
		args->nfs_server.export_path = c;

		status = nfs_try_mount(args, mntfh);
		if (status)
			return status;

		break;
		}
	}

	if (!(args->flags & NFS_MOUNT_SECFLAVOUR))
		args->auth_flavors[0] = RPC_AUTH_UNIX;

#ifndef CONFIG_NFS_V3
	if (args->flags & NFS_MOUNT_VER3)
		goto out_v3_not_compiled;
#endif /* !CONFIG_NFS_V3 */

	return 0;

out_no_data:
	dfprintk(MOUNT, "NFS: mount program didn't pass any mount data\n");
	return -EINVAL;

out_no_v3:
	dfprintk(MOUNT, "NFS: nfs_mount_data version %d does not support v3\n",
		 data->version);
	return -EINVAL;

out_no_sec:
	dfprintk(MOUNT, "NFS: nfs_mount_data version supports only AUTH_SYS\n");
	return -EINVAL;

#ifndef CONFIG_NFS_V3
out_v3_not_compiled:
	dfprintk(MOUNT, "NFS: NFSv3 is not compiled into kernel\n");
	return -EPROTONOSUPPORT;
#endif /* !CONFIG_NFS_V3 */

out_no_address:
	dfprintk(MOUNT, "NFS: mount program didn't pass remote address\n");
	return -EINVAL;

out_invalid_fh:
	dfprintk(MOUNT, "NFS: invalid root filehandle\n");
	return -EINVAL;
}

/*
 * Initialise the common bits of the superblock
 */
static inline void nfs_initialise_sb(struct super_block *sb)
{
	struct nfs_server *server = NFS_SB(sb);

	sb->s_magic = NFS_SUPER_MAGIC;

	/* We probably want something more informative here */
	snprintf(sb->s_id, sizeof(sb->s_id),
		 "%x:%x", MAJOR(sb->s_dev), MINOR(sb->s_dev));

	if (sb->s_blocksize == 0)
		sb->s_blocksize = nfs_block_bits(server->wsize,
						 &sb->s_blocksize_bits);

	if (server->flags & NFS_MOUNT_NOAC)
		sb->s_flags |= MS_SYNCHRONOUS;

	nfs_super_set_maxbytes(sb, server->maxfilesize);
}

/*
 * Finish setting up an NFS2/3 superblock
 */
static void nfs_fill_super(struct super_block *sb,
			   struct nfs_parsed_mount_data *data)
{
	struct nfs_server *server = NFS_SB(sb);

	sb->s_blocksize_bits = 0;
	sb->s_blocksize = 0;
	if (data->bsize)
		sb->s_blocksize = nfs_block_size(data->bsize, &sb->s_blocksize_bits);

	if (server->flags & NFS_MOUNT_VER3) {
		/* The VFS shouldn't apply the umask to mode bits. We will do
		 * so ourselves when necessary.
		 */
		sb->s_flags |= MS_POSIXACL;
		sb->s_time_gran = 1;
	}

	sb->s_op = &nfs_sops;
 	nfs_initialise_sb(sb);
}

/*
 * Finish setting up a cloned NFS2/3 superblock
 */
static void nfs_clone_super(struct super_block *sb,
			    const struct super_block *old_sb)
{
	struct nfs_server *server = NFS_SB(sb);

	sb->s_blocksize_bits = old_sb->s_blocksize_bits;
	sb->s_blocksize = old_sb->s_blocksize;
	sb->s_maxbytes = old_sb->s_maxbytes;

	if (server->flags & NFS_MOUNT_VER3) {
		/* The VFS shouldn't apply the umask to mode bits. We will do
		 * so ourselves when necessary.
		 */
		sb->s_flags |= MS_POSIXACL;
		sb->s_time_gran = 1;
	}

	sb->s_op = old_sb->s_op;
 	nfs_initialise_sb(sb);
}

#define NFS_MS_MASK (MS_RDONLY|MS_NOSUID|MS_NODEV|MS_NOEXEC|MS_SYNCHRONOUS)

static int nfs_compare_mount_options(const struct super_block *s, const struct nfs_server *b, int flags)
{
	const struct nfs_server *a = s->s_fs_info;
	const struct rpc_clnt *clnt_a = a->client;
	const struct rpc_clnt *clnt_b = b->client;

	if ((s->s_flags & NFS_MS_MASK) != (flags & NFS_MS_MASK))
		goto Ebusy;
	if (a->nfs_client != b->nfs_client)
		goto Ebusy;
	if (a->flags != b->flags)
		goto Ebusy;
	if (a->wsize != b->wsize)
		goto Ebusy;
	if (a->rsize != b->rsize)
		goto Ebusy;
	if (a->acregmin != b->acregmin)
		goto Ebusy;
	if (a->acregmax != b->acregmax)
		goto Ebusy;
	if (a->acdirmin != b->acdirmin)
		goto Ebusy;
	if (a->acdirmax != b->acdirmax)
		goto Ebusy;
	if (clnt_a->cl_auth->au_flavor != clnt_b->cl_auth->au_flavor)
		goto Ebusy;
	return 1;
Ebusy:
	return 0;
}

struct nfs_sb_mountdata {
	struct nfs_server *server;
	int mntflags;
};

static int nfs_set_super(struct super_block *s, void *data)
{
	struct nfs_sb_mountdata *sb_mntdata = data;
	struct nfs_server *server = sb_mntdata->server;
	int ret;

	s->s_flags = sb_mntdata->mntflags;
	s->s_fs_info = server;
	ret = set_anon_super(s, server);
	if (ret == 0)
		server->s_dev = s->s_dev;
	return ret;
}

static int nfs_compare_super(struct super_block *sb, void *data)
{
	struct nfs_sb_mountdata *sb_mntdata = data;
	struct nfs_server *server = sb_mntdata->server, *old = NFS_SB(sb);
	int mntflags = sb_mntdata->mntflags;

	if (memcmp(&old->nfs_client->cl_addr,
				&server->nfs_client->cl_addr,
				sizeof(old->nfs_client->cl_addr)) != 0)
		return 0;
	/* Note: NFS_MOUNT_UNSHARED == NFS4_MOUNT_UNSHARED */
	if (old->flags & NFS_MOUNT_UNSHARED)
		return 0;
	if (memcmp(&old->fsid, &server->fsid, sizeof(old->fsid)) != 0)
		return 0;
	return nfs_compare_mount_options(sb, server, mntflags);
}

static int nfs_get_sb(struct file_system_type *fs_type,
	int flags, const char *dev_name, void *raw_data, struct vfsmount *mnt)
{
	struct nfs_server *server = NULL;
	struct super_block *s;
	struct nfs_fh mntfh;
	struct nfs_parsed_mount_data data;
	struct dentry *mntroot;
	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
	struct nfs_sb_mountdata sb_mntdata = {
		.mntflags = flags,
	};
	int error;

	/* Validate the mount data */
	error = nfs_validate_mount_data(raw_data, &data, &mntfh, dev_name);
	if (error < 0)
		goto out;

	/* Get a volume representation */
	server = nfs_create_server(&data, &mntfh);
	if (IS_ERR(server)) {
		error = PTR_ERR(server);
		goto out;
	}
	sb_mntdata.server = server;

	if (server->flags & NFS_MOUNT_UNSHARED)
		compare_super = NULL;

	/* Get a superblock - note that we may end up sharing one that already exists */
	s = sget(fs_type, compare_super, nfs_set_super, &sb_mntdata);
	if (IS_ERR(s)) {
		error = PTR_ERR(s);
		goto out_err_nosb;
	}

	if (s->s_fs_info != server) {
		nfs_free_server(server);
		server = NULL;
	}

	if (!s->s_root) {
		/* initial superblock/root creation */
		nfs_fill_super(s, &data);
	}

	mntroot = nfs_get_root(s, &mntfh);
	if (IS_ERR(mntroot)) {
		error = PTR_ERR(mntroot);
		goto error_splat_super;
	}

	s->s_flags |= MS_ACTIVE;
	mnt->mnt_sb = s;
	mnt->mnt_root = mntroot;
	error = 0;

out:
	kfree(data.nfs_server.hostname);
	return error;

out_err_nosb:
	nfs_free_server(server);
	goto out;

error_splat_super:
	up_write(&s->s_umount);
	deactivate_super(s);
	goto out;
}

/*
 * Destroy an NFS2/3 superblock
 */
static void nfs_kill_super(struct super_block *s)
{
	struct nfs_server *server = NFS_SB(s);

	kill_anon_super(s);
	nfs_free_server(server);
}

/*
 * Clone an NFS2/3 server record on xdev traversal (FSID-change)
 */
static int nfs_xdev_get_sb(struct file_system_type *fs_type, int flags,
			   const char *dev_name, void *raw_data,
			   struct vfsmount *mnt)
{
	struct nfs_clone_mount *data = raw_data;
	struct super_block *s;
	struct nfs_server *server;
	struct dentry *mntroot;
	int (*compare_super)(struct super_block *, void *) = nfs_compare_super;
	struct nfs_sb_mountdata sb_mntdata = {
		.mntflags = flags,
	};
	int error;

	dprintk("--> nfs_xdev_get_sb()\n");

	/* create a new volume representation */
	server = nfs_clone_server(NFS_SB(data->sb), data->fh, data->fattr);
	if (IS_ERR(server)) {
		error = PTR_ERR(server);
		goto out_err_noserver;
	}
	sb_mntdata.server = server;