NFS: pnfs IPv6 support

[deliverable/linux.git] / fs / nfs / nfs4filelayoutdev.c

/*
 *  Device operations for the pnfs nfs4 file layout driver.
 *
 *  Copyright (c) 2002
 *  The Regents of the University of Michigan
 *  All Rights Reserved
 *
 *  Dean Hildebrand <dhildebz@umich.edu>
 *  Garth Goodson   <Garth.Goodson@netapp.com>
 *
 *  Permission is granted to use, copy, create derivative works, and
 *  redistribute this software and such derivative works for any purpose,
 *  so long as the name of the University of Michigan is not used in
 *  any advertising or publicity pertaining to the use or distribution
 *  of this software without specific, written prior authorization. If
 *  the above copyright notice or any other identification of the
 *  University of Michigan is included in any copy of any portion of
 *  this software, then the disclaimer below must also be included.
 *
 *  This software is provided as is, without representation or warranty
 *  of any kind either express or implied, including without limitation
 *  the implied warranties of merchantability, fitness for a particular
 *  purpose, or noninfringement.  The Regents of the University of
 *  Michigan shall not be liable for any damages, including special,
 *  indirect, incidental, or consequential damages, with respect to any
 *  claim arising out of or in connection with the use of the software,
 *  even if it has been or is hereafter advised of the possibility of
 *  such damages.
 */

#include <linux/nfs_fs.h>
#include <linux/vmalloc.h>

#include "internal.h"
#include "nfs4filelayout.h"

#define NFSDBG_FACILITY		NFSDBG_PNFS_LD

/*
 * Data server cache
 *
 * Data servers can be mapped to different device ids.
 * nfs4_pnfs_ds reference counting
 *   - set to 1 on allocation
 *   - incremented when a device id maps a data server already in the cache.
 *   - decremented when deviceid is removed from the cache.
 */
DEFINE_SPINLOCK(nfs4_ds_cache_lock);
static LIST_HEAD(nfs4_data_server_cache);

/* Debug routines */
void
print_ds(struct nfs4_pnfs_ds *ds)
{
	if (ds == NULL) {
		printk("%s NULL device\n", __func__);
		return;
	}
	printk("        ds %s\n"
		"        ref count %d\n"
		"        client %p\n"
		"        cl_exchange_flags %x\n",
		ds->ds_remotestr,
		atomic_read(&ds->ds_count), ds->ds_clp,
		ds->ds_clp ? ds->ds_clp->cl_exchange_flags : 0);
}

/* nfs4_ds_cache_lock is held */
static struct nfs4_pnfs_ds *
_data_server_lookup_locked(struct sockaddr *addr, size_t addrlen)
{
	struct nfs4_pnfs_ds *ds;
	struct sockaddr_in *a, *b;
	struct sockaddr_in6 *a6, *b6;

	list_for_each_entry(ds, &nfs4_data_server_cache, ds_node) {
		if (addr->sa_family != ds->ds_addr.ss_family)
			continue;

		switch (addr->sa_family) {
		case AF_INET:
			a = (struct sockaddr_in *)addr;
			b = (struct sockaddr_in *)&ds->ds_addr;

			if (a->sin_addr.s_addr == b->sin_addr.s_addr &&
			    a->sin_port == b->sin_port)
				return ds;
			break;

		case AF_INET6:
			a6 = (struct sockaddr_in6 *)addr;
			b6 = (struct sockaddr_in6 *)&ds->ds_addr;

			/* LINKLOCAL addresses must have matching scope_id */
			if (ipv6_addr_scope(&a6->sin6_addr) ==
			    IPV6_ADDR_SCOPE_LINKLOCAL &&
			    a6->sin6_scope_id != b6->sin6_scope_id)
				continue;

			if (ipv6_addr_equal(&a6->sin6_addr, &b6->sin6_addr) &&
			    a6->sin6_port == b6->sin6_port)
				return ds;
			break;

		default:
			dprintk("%s: unhandled address family: %u\n",
				__func__, addr->sa_family);
			return NULL;
		}
	}
	return NULL;
}

/*
 * Create an rpc connection to the nfs4_pnfs_ds data server
 * Currently only support IPv4
 */
static int
nfs4_ds_connect(struct nfs_server *mds_srv, struct nfs4_pnfs_ds *ds)
{
	struct nfs_client *clp;
	int status = 0;

	dprintk("--> %s addr %s au_flavor %d\n", __func__, ds->ds_remotestr,
		mds_srv->nfs_client->cl_rpcclient->cl_auth->au_flavor);

	clp = nfs4_set_ds_client(mds_srv->nfs_client,
				 (struct sockaddr *)&ds->ds_addr,
				 ds->ds_addrlen, IPPROTO_TCP);
	if (IS_ERR(clp)) {
		status = PTR_ERR(clp);
		goto out;
	}

	if ((clp->cl_exchange_flags & EXCHGID4_FLAG_MASK_PNFS) != 0) {
		if (!is_ds_client(clp)) {
			status = -ENODEV;
			goto out_put;
		}
		ds->ds_clp = clp;
		dprintk("%s [existing] server=%s\n", __func__,
			ds->ds_remotestr);
		goto out;
	}

	/*
	 * Do not set NFS_CS_CHECK_LEASE_TIME instead set the DS lease to
	 * be equal to the MDS lease. Renewal is scheduled in create_session.
	 */
	spin_lock(&mds_srv->nfs_client->cl_lock);
	clp->cl_lease_time = mds_srv->nfs_client->cl_lease_time;
	spin_unlock(&mds_srv->nfs_client->cl_lock);
	clp->cl_last_renewal = jiffies;

	/* New nfs_client */
	status = nfs4_init_ds_session(clp);
	if (status)
		goto out_put;

	ds->ds_clp = clp;
	dprintk("%s [new] addr: %s\n", __func__, ds->ds_remotestr);
out:
	return status;
out_put:
	nfs_put_client(clp);
	goto out;
}

static void
destroy_ds(struct nfs4_pnfs_ds *ds)
{
	dprintk("--> %s\n", __func__);
	ifdebug(FACILITY)
		print_ds(ds);

	if (ds->ds_clp)
		nfs_put_client(ds->ds_clp);
	kfree(ds->ds_remotestr);
	kfree(ds);
}

void
nfs4_fl_free_deviceid(struct nfs4_file_layout_dsaddr *dsaddr)
{
	struct nfs4_pnfs_ds *ds;
	int i;

	nfs4_print_deviceid(&dsaddr->id_node.deviceid);

	for (i = 0; i < dsaddr->ds_num; i++) {
		ds = dsaddr->ds_list[i];
		if (ds != NULL) {
			if (atomic_dec_and_lock(&ds->ds_count,
						&nfs4_ds_cache_lock)) {
				list_del_init(&ds->ds_node);
				spin_unlock(&nfs4_ds_cache_lock);
				destroy_ds(ds);
			}
		}
	}
	kfree(dsaddr->stripe_indices);
	kfree(dsaddr);
}

/*
 * Create a string with a human readable address and port to avoid
 * complicated setup around many dprinks.
 */
static char *
nfs4_pnfs_remotestr(struct sockaddr *ds_addr, gfp_t gfp_flags)
{
	char buf[INET6_ADDRSTRLEN + IPV6_SCOPE_ID_LEN];
	char *remotestr;
	char *startsep = "";
	char *endsep = "";
	size_t len;
	uint16_t port;

	switch (ds_addr->sa_family) {
	case AF_INET:
		port = ((struct sockaddr_in *)ds_addr)->sin_port;
		break;
	case AF_INET6:
		startsep = "[";
		endsep = "]";
		port = ((struct sockaddr_in6 *)ds_addr)->sin6_port;
		break;
	default:
		dprintk("%s: Unknown address family %u\n",
			__func__, ds_addr->sa_family);
		return NULL;
	}

	if (!rpc_ntop((struct sockaddr *)ds_addr, buf, sizeof(buf))) {
		dprintk("%s: error printing addr\n", __func__);
		return NULL;
	}

	len = strlen(buf) + strlen(startsep) + strlen(endsep) + 1 + 5 + 1;
	remotestr = kzalloc(len, gfp_flags);

	if (unlikely(!remotestr)) {
		dprintk("%s: couldn't alloc remotestr\n", __func__);
		return NULL;
	}

	snprintf(remotestr, len, "%s%s%s:%u",
		 startsep, buf, endsep, ntohs(port));

	return remotestr;
}

static struct nfs4_pnfs_ds *
nfs4_pnfs_ds_add(struct sockaddr *addr, size_t addrlen, gfp_t gfp_flags)
{
	struct nfs4_pnfs_ds *tmp_ds, *ds = NULL;
	char *remotestr;

	ds = kzalloc(sizeof(*tmp_ds), gfp_flags);
	if (!ds)
		goto out;

	/* this is only used for debugging, so it's ok if its NULL */
	remotestr = nfs4_pnfs_remotestr(addr, gfp_flags);

	spin_lock(&nfs4_ds_cache_lock);
	tmp_ds = _data_server_lookup_locked(addr, addrlen);
	if (tmp_ds == NULL) {
		memcpy(&ds->ds_addr, addr, addrlen);
		ds->ds_addrlen = addrlen;
		ds->ds_remotestr = remotestr;
		atomic_set(&ds->ds_count, 1);
		INIT_LIST_HEAD(&ds->ds_node);
		ds->ds_clp = NULL;
		list_add(&ds->ds_node, &nfs4_data_server_cache);
		dprintk("%s add new data server %s\n", __func__,
			ds->ds_remotestr);
	} else {
		kfree(remotestr);
		kfree(ds);
		atomic_inc(&tmp_ds->ds_count);
		dprintk("%s data server %s found, inc'ed ds_count to %d\n",
			__func__, tmp_ds->ds_remotestr,
			atomic_read(&tmp_ds->ds_count));
		ds = tmp_ds;
	}
	spin_unlock(&nfs4_ds_cache_lock);
out:
	return ds;
}

/*
 * Currently only supports ipv4, ipv6 and one multi-path address.
 */
static struct nfs4_pnfs_ds *
decode_and_add_ds(struct xdr_stream *streamp, struct inode *inode, gfp_t gfp_flags)
{
	struct nfs4_pnfs_ds *ds = NULL;
	char *buf, *portstr;
	struct sockaddr_storage ss;
	size_t sslen;
	u32 port;
	int nlen, rlen;
	int tmp[2];
	__be32 *p;
	char *netid, *match_netid;
	size_t match_netid_len;

	/* r_netid */
	p = xdr_inline_decode(streamp, 4);
	if (unlikely(!p))
		goto out_err;
	nlen = be32_to_cpup(p++);

	p = xdr_inline_decode(streamp, nlen);
	if (unlikely(!p))
		goto out_err;

	netid = kmalloc(nlen+1, gfp_flags);
	if (unlikely(!netid))
		goto out_err;

	netid[nlen] = '\0';
	memcpy(netid, p, nlen);

	/* r_addr: ip/ip6addr with port in dec octets - see RFC 5665 */
	p = xdr_inline_decode(streamp, 4);
	if (unlikely(!p))
		goto out_free_netid;
	rlen = be32_to_cpup(p);

	p = xdr_inline_decode(streamp, rlen);
	if (unlikely(!p))
		goto out_free_netid;

	/* port is ".ABC.DEF", 8 chars max */
	if (rlen > INET6_ADDRSTRLEN + IPV6_SCOPE_ID_LEN + 8) {
		dprintk("%s: Invalid address, length %d\n", __func__,
			rlen);
		goto out_free_netid;
	}
	buf = kmalloc(rlen + 1, gfp_flags);
	if (!buf) {
		dprintk("%s: Not enough memory\n", __func__);
		goto out_free_netid;
	}
	buf[rlen] = '\0';
	memcpy(buf, p, rlen);

	/* replace port '.' with '-' */
	portstr = strrchr(buf, '.');
	if (!portstr) {
		dprintk("%s: Failed finding expected dot in port\n",
			__func__);
		goto out_free_buf;
	}
	*portstr = '-';

	/* find '.' between address and port */
	portstr = strrchr(buf, '.');
	if (!portstr) {
		dprintk("%s: Failed finding expected dot between address and "
			"port\n", __func__);
		goto out_free_buf;
	}
	*portstr = '\0';

	if (!rpc_pton(buf, portstr-buf, (struct sockaddr *)&ss, sizeof(ss))) {
		dprintk("%s: Error parsing address %s\n", __func__, buf);
		goto out_free_buf;
	}

	portstr++;
	sscanf(portstr, "%d-%d", &tmp[0], &tmp[1]);
	port = htons((tmp[0] << 8) | (tmp[1]));

	switch (ss.ss_family) {
	case AF_INET:
		((struct sockaddr_in *)&ss)->sin_port = port;
		sslen = sizeof(struct sockaddr_in);
		match_netid = "tcp";
		match_netid_len = 3;
		break;

	case AF_INET6:
		((struct sockaddr_in6 *)&ss)->sin6_port = port;
		sslen = sizeof(struct sockaddr_in6);
		match_netid = "tcp6";
		match_netid_len = 4;
		break;

	default:
		dprintk("%s: unsupported address family: %u\n",
			__func__, ss.ss_family);
		goto out_free_buf;
	}

	if (nlen != match_netid_len || strncmp(netid, match_netid, nlen)) {
		dprintk("%s: ERROR: r_netid \"%s\" != \"%s\"\n",
			__func__, netid, match_netid);
		goto out_free_buf;
	}

	ds = nfs4_pnfs_ds_add((struct sockaddr *)&ss, sslen, gfp_flags);
	dprintk("%s: Added DS %s\n", __func__, ds->ds_remotestr);
out_free_buf:
	kfree(buf);
out_free_netid:
	kfree(netid);
out_err:
	return ds;
}

/* Decode opaque device data and return the result */
static struct nfs4_file_layout_dsaddr*
decode_device(struct inode *ino, struct pnfs_device *pdev, gfp_t gfp_flags)
{
	int i;
	u32 cnt, num;
	u8 *indexp;
	__be32 *p;
	u8 *stripe_indices;
	u8 max_stripe_index;
	struct nfs4_file_layout_dsaddr *dsaddr = NULL;
	struct xdr_stream stream;
	struct xdr_buf buf;
	struct page *scratch;

	/* set up xdr stream */
	scratch = alloc_page(gfp_flags);
	if (!scratch)
		goto out_err;

	xdr_init_decode_pages(&stream, &buf, pdev->pages, pdev->pglen);
	xdr_set_scratch_buffer(&stream, page_address(scratch), PAGE_SIZE);

	/* Get the stripe count (number of stripe index) */
	p = xdr_inline_decode(&stream, 4);
	if (unlikely(!p))
		goto out_err_free_scratch;

	cnt = be32_to_cpup(p);
	dprintk("%s stripe count  %d\n", __func__, cnt);
	if (cnt > NFS4_PNFS_MAX_STRIPE_CNT) {
		printk(KERN_WARNING "%s: stripe count %d greater than "
		       "supported maximum %d\n", __func__,
			cnt, NFS4_PNFS_MAX_STRIPE_CNT);
		goto out_err_free_scratch;
	}

	/* read stripe indices */
	stripe_indices = kcalloc(cnt, sizeof(u8), gfp_flags);
	if (!stripe_indices)
		goto out_err_free_scratch;

	p = xdr_inline_decode(&stream, cnt << 2);
	if (unlikely(!p))
		goto out_err_free_stripe_indices;

	indexp = &stripe_indices[0];
	max_stripe_index = 0;
	for (i = 0; i < cnt; i++) {
		*indexp = be32_to_cpup(p++);
		max_stripe_index = max(max_stripe_index, *indexp);
		indexp++;
	}

	/* Check the multipath list count */
	p = xdr_inline_decode(&stream, 4);
	if (unlikely(!p))
		goto out_err_free_stripe_indices;

	num = be32_to_cpup(p);
	dprintk("%s ds_num %u\n", __func__, num);
	if (num > NFS4_PNFS_MAX_MULTI_CNT) {
		printk(KERN_WARNING "%s: multipath count %d greater than "
			"supported maximum %d\n", __func__,
			num, NFS4_PNFS_MAX_MULTI_CNT);
		goto out_err_free_stripe_indices;
	}

	/* validate stripe indices are all < num */
	if (max_stripe_index >= num) {
		printk(KERN_WARNING "%s: stripe index %u >= num ds %u\n",
			__func__, max_stripe_index, num);
		goto out_err_free_stripe_indices;
	}

	dsaddr = kzalloc(sizeof(*dsaddr) +
			(sizeof(struct nfs4_pnfs_ds *) * (num - 1)),
			gfp_flags);
	if (!dsaddr)
		goto out_err_free_stripe_indices;

	dsaddr->stripe_count = cnt;
	dsaddr->stripe_indices = stripe_indices;
	stripe_indices = NULL;
	dsaddr->ds_num = num;
	nfs4_init_deviceid_node(&dsaddr->id_node,
				NFS_SERVER(ino)->pnfs_curr_ld,
				NFS_SERVER(ino)->nfs_client,
				&pdev->dev_id);

	for (i = 0; i < dsaddr->ds_num; i++) {
		int j;
		u32 mp_count;

		p = xdr_inline_decode(&stream, 4);
		if (unlikely(!p))
			goto out_err_free_deviceid;

		mp_count = be32_to_cpup(p); /* multipath count */
		if (mp_count > 1) {
			printk(KERN_WARNING
			       "%s: Multipath count %d not supported, "
			       "skipping all greater than 1\n", __func__,
				mp_count);
		}
		for (j = 0; j < mp_count; j++) {
			if (j == 0) {
				dsaddr->ds_list[i] = decode_and_add_ds(&stream,
					ino, gfp_flags);
				if (dsaddr->ds_list[i] == NULL)
					goto out_err_free_deviceid;
			} else {
				u32 len;
				/* skip extra multipath */

				/* read len, skip */
				p = xdr_inline_decode(&stream, 4);
				if (unlikely(!p))
					goto out_err_free_deviceid;
				len = be32_to_cpup(p);

				p = xdr_inline_decode(&stream, len);
				if (unlikely(!p))
					goto out_err_free_deviceid;

				/* read len, skip */
				p = xdr_inline_decode(&stream, 4);
				if (unlikely(!p))
					goto out_err_free_deviceid;
				len = be32_to_cpup(p);

				p = xdr_inline_decode(&stream, len);
				if (unlikely(!p))
					goto out_err_free_deviceid;
			}
		}
	}

	__free_page(scratch);
	return dsaddr;

out_err_free_deviceid:
	nfs4_fl_free_deviceid(dsaddr);
	/* stripe_indicies was part of dsaddr */
	goto out_err_free_scratch;
out_err_free_stripe_indices:
	kfree(stripe_indices);
out_err_free_scratch:
	__free_page(scratch);
out_err:
	dprintk("%s ERROR: returning NULL\n", __func__);
	return NULL;
}

/*
 * Decode the opaque device specified in 'dev' and add it to the cache of
 * available devices.
 */
static struct nfs4_file_layout_dsaddr *
decode_and_add_device(struct inode *inode, struct pnfs_device *dev, gfp_t gfp_flags)
{
	struct nfs4_deviceid_node *d;
	struct nfs4_file_layout_dsaddr *n, *new;

	new = decode_device(inode, dev, gfp_flags);
	if (!new) {
		printk(KERN_WARNING "%s: Could not decode or add device\n",
			__func__);
		return NULL;
	}

	d = nfs4_insert_deviceid_node(&new->id_node);
	n = container_of(d, struct nfs4_file_layout_dsaddr, id_node);
	if (n != new) {
		nfs4_fl_free_deviceid(new);
		return n;
	}

	return new;
}

/*
 * Retrieve the information for dev_id, add it to the list
 * of available devices, and return it.
 */
struct nfs4_file_layout_dsaddr *
get_device_info(struct inode *inode, struct nfs4_deviceid *dev_id, gfp_t gfp_flags)
{
	struct pnfs_device *pdev = NULL;
	u32 max_resp_sz;
	int max_pages;
	struct page **pages = NULL;
	struct nfs4_file_layout_dsaddr *dsaddr = NULL;
	int rc, i;
	struct nfs_server *server = NFS_SERVER(inode);

	/*
	 * Use the session max response size as the basis for setting
	 * GETDEVICEINFO's maxcount
	 */
	max_resp_sz = server->nfs_client->cl_session->fc_attrs.max_resp_sz;
	max_pages = max_resp_sz >> PAGE_SHIFT;
	dprintk("%s inode %p max_resp_sz %u max_pages %d\n",
		__func__, inode, max_resp_sz, max_pages);

	pdev = kzalloc(sizeof(struct pnfs_device), gfp_flags);
	if (pdev == NULL)
		return NULL;

	pages = kzalloc(max_pages * sizeof(struct page *), gfp_flags);
	if (pages == NULL) {
		kfree(pdev);
		return NULL;
	}
	for (i = 0; i < max_pages; i++) {
		pages[i] = alloc_page(gfp_flags);
		if (!pages[i])
			goto out_free;
	}

	memcpy(&pdev->dev_id, dev_id, sizeof(*dev_id));
	pdev->layout_type = LAYOUT_NFSV4_1_FILES;
	pdev->pages = pages;
	pdev->pgbase = 0;
	pdev->pglen = PAGE_SIZE * max_pages;
	pdev->mincount = 0;

	rc = nfs4_proc_getdeviceinfo(server, pdev);
	dprintk("%s getdevice info returns %d\n", __func__, rc);
	if (rc)
		goto out_free;

	/*
	 * Found new device, need to decode it and then add it to the
	 * list of known devices for this mountpoint.
	 */
	dsaddr = decode_and_add_device(inode, pdev, gfp_flags);
out_free:
	for (i = 0; i < max_pages; i++)
		__free_page(pages[i]);
	kfree(pages);
	kfree(pdev);
	dprintk("<-- %s dsaddr %p\n", __func__, dsaddr);
	return dsaddr;
}

void
nfs4_fl_put_deviceid(struct nfs4_file_layout_dsaddr *dsaddr)
{
	nfs4_put_deviceid_node(&dsaddr->id_node);
}

/*
 * Want res = (offset - layout->pattern_offset)/ layout->stripe_unit
 * Then: ((res + fsi) % dsaddr->stripe_count)
 */
u32
nfs4_fl_calc_j_index(struct pnfs_layout_segment *lseg, loff_t offset)
{
	struct nfs4_filelayout_segment *flseg = FILELAYOUT_LSEG(lseg);
	u64 tmp;

	tmp = offset - flseg->pattern_offset;
	do_div(tmp, flseg->stripe_unit);
	tmp += flseg->first_stripe_index;
	return do_div(tmp, flseg->dsaddr->stripe_count);
}

u32
nfs4_fl_calc_ds_index(struct pnfs_layout_segment *lseg, u32 j)
{
	return FILELAYOUT_LSEG(lseg)->dsaddr->stripe_indices[j];
}

struct nfs_fh *
nfs4_fl_select_ds_fh(struct pnfs_layout_segment *lseg, u32 j)
{
	struct nfs4_filelayout_segment *flseg = FILELAYOUT_LSEG(lseg);
	u32 i;

	if (flseg->stripe_type == STRIPE_SPARSE) {
		if (flseg->num_fh == 1)
			i = 0;
		else if (flseg->num_fh == 0)
			/* Use the MDS OPEN fh set in nfs_read_rpcsetup */
			return NULL;
		else
			i = nfs4_fl_calc_ds_index(lseg, j);
	} else
		i = j;
	return flseg->fh_array[i];
}

static void
filelayout_mark_devid_negative(struct nfs4_file_layout_dsaddr *dsaddr,
			       int err, const char *ds_remotestr)
{
	u32 *p = (u32 *)&dsaddr->id_node.deviceid;

	printk(KERN_ERR "NFS: data server %s connection error %d."
		" Deviceid [%x%x%x%x] marked out of use.\n",
		ds_remotestr, err, p[0], p[1], p[2], p[3]);

	spin_lock(&nfs4_ds_cache_lock);
	dsaddr->flags |= NFS4_DEVICE_ID_NEG_ENTRY;
	spin_unlock(&nfs4_ds_cache_lock);
}

struct nfs4_pnfs_ds *
nfs4_fl_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx)
{
	struct nfs4_file_layout_dsaddr *dsaddr = FILELAYOUT_LSEG(lseg)->dsaddr;
	struct nfs4_pnfs_ds *ds = dsaddr->ds_list[ds_idx];

	if (ds == NULL) {
		printk(KERN_ERR "%s: No data server for offset index %d\n",
			__func__, ds_idx);
		return NULL;
	}

	if (!ds->ds_clp) {
		struct nfs_server *s = NFS_SERVER(lseg->pls_layout->plh_inode);
		int err;

		if (dsaddr->flags & NFS4_DEVICE_ID_NEG_ENTRY) {
			/* Already tried to connect, don't try again */
			dprintk("%s Deviceid marked out of use\n", __func__);
			return NULL;
		}
		err = nfs4_ds_connect(s, ds);
		if (err) {
			filelayout_mark_devid_negative(dsaddr, err,
						       ds->ds_remotestr);
			return NULL;
		}
	}
	return ds;
}