fs/nfs/flexfilelayout/flexfilelayoutdev.c - kernel/msm-4.9 - Gitiles

 /*
  * Device operations for the pnfs nfs4 file layout driver.
  *
  * Copyright (c) 2014, Primary Data, Inc. All rights reserved.
  *
  * Tao Peng <bergwolf@primarydata.com>
  */

 #include <linux/nfs_fs.h>
 #include <linux/vmalloc.h>
 #include <linux/module.h>
 #include <linux/sunrpc/addr.h>

 #include "../internal.h"
 #include "../nfs4session.h"
 #include "flexfilelayout.h"

 #define NFSDBG_FACILITY		NFSDBG_PNFS_LD

 static unsigned int dataserver_timeo = NFS4_DEF_DS_TIMEO;
 static unsigned int dataserver_retrans = NFS4_DEF_DS_RETRANS;

 void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
 {
 	if (mirror_ds)
 		nfs4_put_deviceid_node(&mirror_ds->id_node);
 }

 void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
 {
 	nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
 	nfs4_pnfs_ds_put(mirror_ds->ds);
 	kfree_rcu(mirror_ds, id_node.rcu);
 }

 /* Decode opaque device data and construct new_ds using it */
 struct nfs4_ff_layout_ds *
 nfs4_ff_alloc_deviceid_node(struct nfs_server *server, struct pnfs_device *pdev,
 			    gfp_t gfp_flags)
 {
 	struct xdr_stream stream;
 	struct xdr_buf buf;
 	struct page *scratch;
 	struct list_head dsaddrs;
 	struct nfs4_pnfs_ds_addr *da;
 	struct nfs4_ff_layout_ds *new_ds = NULL;
 	struct nfs4_ff_ds_version *ds_versions = NULL;
 	u32 mp_count;
 	u32 version_count;
 	__be32 *p;
 	int i, ret = -ENOMEM;

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

 	new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags);
 	if (!new_ds)
 		goto out_scratch;

 	nfs4_init_deviceid_node(&new_ds->id_node,
 				server,
 				&pdev->dev_id);
 	INIT_LIST_HEAD(&dsaddrs);

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

 	/* multipath count */
 	p = xdr_inline_decode(&stream, 4);
 	if (unlikely(!p))
 		goto out_err_drain_dsaddrs;
 	mp_count = be32_to_cpup(p);
 	dprintk("%s: multipath ds count %d\n", __func__, mp_count);

 	for (i = 0; i < mp_count; i++) {
 		/* multipath ds */
 		da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net,
 					    &stream, gfp_flags);
 		if (da)
 			list_add_tail(&da->da_node, &dsaddrs);
 	}
 	if (list_empty(&dsaddrs)) {
 		dprintk("%s: no suitable DS addresses found\n",
 			__func__);
 		ret = -ENOMEDIUM;
 		goto out_err_drain_dsaddrs;
 	}

 	/* version count */
 	p = xdr_inline_decode(&stream, 4);
 	if (unlikely(!p))
 		goto out_err_drain_dsaddrs;
 	version_count = be32_to_cpup(p);
 	dprintk("%s: version count %d\n", __func__, version_count);

 	ds_versions = kzalloc(version_count * sizeof(struct nfs4_ff_ds_version),
 			      gfp_flags);
 	if (!ds_versions)
 		goto out_scratch;

 	for (i = 0; i < version_count; i++) {
 		/* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
 		 * tightly_coupled(4) */
 		p = xdr_inline_decode(&stream, 20);
 		if (unlikely(!p))
 			goto out_err_drain_dsaddrs;
 		ds_versions[i].version = be32_to_cpup(p++);
 		ds_versions[i].minor_version = be32_to_cpup(p++);
 		ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL);
 		ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL);
 		ds_versions[i].tightly_coupled = be32_to_cpup(p);

 		if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
 			ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
 		if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
 			ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;

 		if (ds_versions[i].version != 3 || ds_versions[i].minor_version != 0) {
 			dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
 				i, ds_versions[i].version,
 				ds_versions[i].minor_version);
 			ret = -EPROTONOSUPPORT;
 			goto out_err_drain_dsaddrs;
 		}

 		dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
 			__func__, i, ds_versions[i].version,
 			ds_versions[i].minor_version,
 			ds_versions[i].rsize,
 			ds_versions[i].wsize,
 			ds_versions[i].tightly_coupled);
 	}

 	new_ds->ds_versions = ds_versions;
 	new_ds->ds_versions_cnt = version_count;

 	new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
 	if (!new_ds->ds)
 		goto out_err_drain_dsaddrs;

 	/* If DS was already in cache, free ds addrs */
 	while (!list_empty(&dsaddrs)) {
 		da = list_first_entry(&dsaddrs,
 				      struct nfs4_pnfs_ds_addr,
 				      da_node);
 		list_del_init(&da->da_node);
 		kfree(da->da_remotestr);
 		kfree(da);
 	}

 	__free_page(scratch);
 	return new_ds;

 out_err_drain_dsaddrs:
 	while (!list_empty(&dsaddrs)) {
 		da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
 				      da_node);
 		list_del_init(&da->da_node);
 		kfree(da->da_remotestr);
 		kfree(da);
 	}

 	kfree(ds_versions);
 out_scratch:
 	__free_page(scratch);
 out_err:
 	kfree(new_ds);

 	dprintk("%s ERROR: returning %d\n", __func__, ret);
 	return NULL;
 }

 static u64
 end_offset(u64 start, u64 len)
 {
 	u64 end;

 	end = start + len;
 	return end >= start ? end : NFS4_MAX_UINT64;
 }

 static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
 			    u64 offset, u64 length)
 {
 	u64 end;

 	end = max_t(u64, end_offset(err->offset, err->length),
 		    end_offset(offset, length));
 	err->offset = min_t(u64, err->offset, offset);
 	err->length = end - err->offset;
 }

 static bool ds_error_can_merge(struct nfs4_ff_layout_ds_err *err,  u64 offset,
 			       u64 length, int status, enum nfs_opnum4 opnum,
 			       nfs4_stateid *stateid,
 			       struct nfs4_deviceid *deviceid)
 {
 	return err->status == status && err->opnum == opnum &&
 	       nfs4_stateid_match(&err->stateid, stateid) &&
 	       !memcmp(&err->deviceid, deviceid, sizeof(*deviceid)) &&
 	       end_offset(err->offset, err->length) >= offset &&
 	       err->offset <= end_offset(offset, length);
 }

 static bool merge_ds_error(struct nfs4_ff_layout_ds_err *old,
 			   struct nfs4_ff_layout_ds_err *new)
 {
 	if (!ds_error_can_merge(old, new->offset, new->length, new->status,
 				new->opnum, &new->stateid, &new->deviceid))
 		return false;

 	extend_ds_error(old, new->offset, new->length);
 	return true;
 }

 static bool
 ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
 			      struct nfs4_ff_layout_ds_err *dserr)
 {
 	struct nfs4_ff_layout_ds_err *err;

 	list_for_each_entry(err, &flo->error_list, list) {
 		if (merge_ds_error(err, dserr)) {
 			return true;
 		}
 	}

 	list_add(&dserr->list, &flo->error_list);
 	return false;
 }

 static bool
 ff_layout_update_ds_error(struct nfs4_flexfile_layout *flo, u64 offset,
 			  u64 length, int status, enum nfs_opnum4 opnum,
 			  nfs4_stateid *stateid, struct nfs4_deviceid *deviceid)
 {
 	bool found = false;
 	struct nfs4_ff_layout_ds_err *err;

 	list_for_each_entry(err, &flo->error_list, list) {
 		if (ds_error_can_merge(err, offset, length, status, opnum,
 				       stateid, deviceid)) {
 			found = true;
 			extend_ds_error(err, offset, length);
 			break;
 		}
 	}

 	return found;
 }

 int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
 			     struct nfs4_ff_layout_mirror *mirror, u64 offset,
 			     u64 length, int status, enum nfs_opnum4 opnum,
 			     gfp_t gfp_flags)
 {
 	struct nfs4_ff_layout_ds_err *dserr;
 	bool needfree;

 	if (status == 0)
 		return 0;

 	if (mirror->mirror_ds == NULL)
 		return -EINVAL;

 	spin_lock(&flo->generic_hdr.plh_inode->i_lock);
 	if (ff_layout_update_ds_error(flo, offset, length, status, opnum,
 				      &mirror->stateid,
 				      &mirror->mirror_ds->id_node.deviceid)) {
 		spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 		return 0;
 	}
 	spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 	dserr = kmalloc(sizeof(*dserr), gfp_flags);
 	if (!dserr)
 		return -ENOMEM;

 	INIT_LIST_HEAD(&dserr->list);
 	dserr->offset = offset;
 	dserr->length = length;
 	dserr->status = status;
 	dserr->opnum = opnum;
 	nfs4_stateid_copy(&dserr->stateid, &mirror->stateid);
 	memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid,
 	       NFS4_DEVICEID4_SIZE);

 	spin_lock(&flo->generic_hdr.plh_inode->i_lock);
 	needfree = ff_layout_add_ds_error_locked(flo, dserr);
 	spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
 	if (needfree)
 		kfree(dserr);

 	return 0;
 }

 /* currently we only support AUTH_NONE and AUTH_SYS */
 static rpc_authflavor_t
 nfs4_ff_layout_choose_authflavor(struct nfs4_ff_layout_mirror *mirror)
 {
 	if (mirror->uid == (u32)-1)
 		return RPC_AUTH_NULL;
 	return RPC_AUTH_UNIX;
 }

 /* fetch cred for NFSv3 DS */
 static int ff_layout_update_mirror_cred(struct nfs4_ff_layout_mirror *mirror,
 				      struct nfs4_pnfs_ds *ds)
 {
 	if (ds->ds_clp && !mirror->cred &&
 	    mirror->mirror_ds->ds_versions[0].version == 3) {
 		struct rpc_auth *auth = ds->ds_clp->cl_rpcclient->cl_auth;
 		struct rpc_cred *cred;
 		struct auth_cred acred = {
 			.uid = make_kuid(&init_user_ns, mirror->uid),
 			.gid = make_kgid(&init_user_ns, mirror->gid),
 		};

 		/* AUTH_NULL ignores acred */
 		cred = auth->au_ops->lookup_cred(auth, &acred, 0);
 		if (IS_ERR(cred)) {
 			dprintk("%s: lookup_cred failed with %ld\n",
 				__func__, PTR_ERR(cred));
 			return PTR_ERR(cred);
 		} else {
 			if (cmpxchg(&mirror->cred, NULL, cred))
 				put_rpccred(cred);
 		}
 	}
 	return 0;
 }

 struct nfs_fh *
 nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx)
 {
 	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, mirror_idx);
 	struct nfs_fh *fh = NULL;
 	struct nfs4_deviceid_node *devid;

 	if (mirror == NULL || mirror->mirror_ds == NULL ||
 	    mirror->mirror_ds->ds == NULL) {
 		printk(KERN_ERR "NFS: %s: No data server for mirror offset index %d\n",
 			__func__, mirror_idx);
 		if (mirror && mirror->mirror_ds) {
 			devid = &mirror->mirror_ds->id_node;
 			pnfs_generic_mark_devid_invalid(devid);
 		}
 		goto out;
 	}

 	/* FIXME: For now assume there is only 1 version available for the DS */
 	fh = &mirror->fh_versions[0];
 out:
 	return fh;
 }

 /* Upon return, either ds is connected, or ds is NULL */
 struct nfs4_pnfs_ds *
 nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
 			  bool fail_return)
 {
 	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 	struct nfs4_pnfs_ds *ds = NULL;
 	struct nfs4_deviceid_node *devid;
 	struct inode *ino = lseg->pls_layout->plh_inode;
 	struct nfs_server *s = NFS_SERVER(ino);
 	unsigned int max_payload;
 	rpc_authflavor_t flavor;

 	if (mirror == NULL || mirror->mirror_ds == NULL ||
 	    mirror->mirror_ds->ds == NULL) {
 		printk(KERN_ERR "NFS: %s: No data server for offset index %d\n",
 			__func__, ds_idx);
 		if (mirror && mirror->mirror_ds) {
 			devid = &mirror->mirror_ds->id_node;
 			pnfs_generic_mark_devid_invalid(devid);
 		}
 		goto out;
 	}

 	devid = &mirror->mirror_ds->id_node;
 	if (ff_layout_test_devid_unavailable(devid))
 		goto out;

 	ds = mirror->mirror_ds->ds;
 	/* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
 	smp_rmb();
 	if (ds->ds_clp)
 		goto out_update_creds;

 	flavor = nfs4_ff_layout_choose_authflavor(mirror);

 	/* FIXME: For now we assume the server sent only one version of NFS
 	 * to use for the DS.
 	 */
 	nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
 			     dataserver_retrans,
 			     mirror->mirror_ds->ds_versions[0].version,
 			     mirror->mirror_ds->ds_versions[0].minor_version,
 			     flavor);

 	/* connect success, check rsize/wsize limit */
 	if (ds->ds_clp) {
 		max_payload =
 			nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
 				       NULL);
 		if (mirror->mirror_ds->ds_versions[0].rsize > max_payload)
 			mirror->mirror_ds->ds_versions[0].rsize = max_payload;
 		if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
 			mirror->mirror_ds->ds_versions[0].wsize = max_payload;
 	} else {
 		ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
 					 mirror, lseg->pls_range.offset,
 					 lseg->pls_range.length, NFS4ERR_NXIO,
 					 OP_ILLEGAL, GFP_NOIO);
 		if (fail_return) {
 			pnfs_error_mark_layout_for_return(ino, lseg);
 			if (ff_layout_has_available_ds(lseg))
 				pnfs_set_retry_layoutget(lseg->pls_layout);
 			else
 				pnfs_clear_retry_layoutget(lseg->pls_layout);

 		} else {
 			if (ff_layout_has_available_ds(lseg))
 				set_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
 					&lseg->pls_layout->plh_flags);
 			else {
 				pnfs_error_mark_layout_for_return(ino, lseg);
 				pnfs_clear_retry_layoutget(lseg->pls_layout);
 			}
 		}
 	}
 out_update_creds:
 	if (ff_layout_update_mirror_cred(mirror, ds))
 		ds = NULL;
 out:
 	return ds;
 }

 struct rpc_cred *
 ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg, u32 ds_idx,
 		      struct rpc_cred *mdscred)
 {
 	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
 	struct rpc_cred *cred = ERR_PTR(-EINVAL);

 	if (!nfs4_ff_layout_prepare_ds(lseg, ds_idx, true))
 		goto out;

 	if (mirror && mirror->cred)
 		cred = mirror->cred;
 	else
 		cred = mdscred;
 out:
 	return cred;
 }

 /**
 * Find or create a DS rpc client with th MDS server rpc client auth flavor
 * in the nfs_client cl_ds_clients list.
 */
 struct rpc_clnt *
 nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg, u32 ds_idx,
 				 struct nfs_client *ds_clp, struct inode *inode)
 {
 	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);

 	switch (mirror->mirror_ds->ds_versions[0].version) {
 	case 3:
 		/* For NFSv3 DS, flavor is set when creating DS connections */
 		return ds_clp->cl_rpcclient;
 	case 4:
 		return nfs4_find_or_create_ds_client(ds_clp, inode);
 	default:
 		BUG();
 	}
 }

 static bool is_range_intersecting(u64 offset1, u64 length1,
 				  u64 offset2, u64 length2)
 {
 	u64 end1 = end_offset(offset1, length1);
 	u64 end2 = end_offset(offset2, length2);

 	return (end1 == NFS4_MAX_UINT64 || end1 > offset2) &&
 	       (end2 == NFS4_MAX_UINT64 || end2 > offset1);
 }

 /* called with inode i_lock held */
 int ff_layout_encode_ds_ioerr(struct nfs4_flexfile_layout *flo,
 			      struct xdr_stream *xdr, int *count,
 			      const struct pnfs_layout_range *range)
 {
 	struct nfs4_ff_layout_ds_err *err, *n;
 	__be32 *p;

 	list_for_each_entry_safe(err, n, &flo->error_list, list) {
 		if (!is_range_intersecting(err->offset, err->length,
 					   range->offset, range->length))
 			continue;
 		/* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
 		 * + deviceid(NFS4_DEVICEID4_SIZE) + status(4) + opnum(4)
 		 */
 		p = xdr_reserve_space(xdr,
 				24 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
 		if (unlikely(!p))
 			return -ENOBUFS;
 		p = xdr_encode_hyper(p, err->offset);
 		p = xdr_encode_hyper(p, err->length);
 		p = xdr_encode_opaque_fixed(p, &err->stateid,
 					    NFS4_STATEID_SIZE);
 		p = xdr_encode_opaque_fixed(p, &err->deviceid,
 					    NFS4_DEVICEID4_SIZE);
 		*p++ = cpu_to_be32(err->status);
 		*p++ = cpu_to_be32(err->opnum);
 		*count += 1;
 		list_del(&err->list);
 		dprintk("%s: offset %llu length %llu status %d op %d count %d\n",
 			__func__, err->offset, err->length, err->status,
 			err->opnum, *count);
 		kfree(err);
 	}

 	return 0;
 }

 bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
 {
 	struct nfs4_ff_layout_mirror *mirror;
 	struct nfs4_deviceid_node *devid;
 	int idx;

 	for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
 		mirror = FF_LAYOUT_COMP(lseg, idx);
 		if (mirror && mirror->mirror_ds) {
 			devid = &mirror->mirror_ds->id_node;
 			if (!ff_layout_test_devid_unavailable(devid))
 				return true;
 		}
 	}

 	return false;
 }

 module_param(dataserver_retrans, uint, 0644);
 MODULE_PARM_DESC(dataserver_retrans, "The  number of times the NFSv4.1 client "
 			"retries a request before it attempts further "
 			" recovery  action.");
 module_param(dataserver_timeo, uint, 0644);
 MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
 			"NFSv4.1  client  waits for a response from a "
 			" data server before it retries an NFS request.");
	/*
	* Device operations for the pnfs nfs4 file layout driver.
	*
	* Copyright (c) 2014, Primary Data, Inc. All rights reserved.
	*
	* Tao Peng <bergwolf@primarydata.com>
	*/

	#include <linux/nfs_fs.h>
	#include <linux/vmalloc.h>
	#include <linux/module.h>
	#include <linux/sunrpc/addr.h>

	#include "../internal.h"
	#include "../nfs4session.h"
	#include "flexfilelayout.h"

	#define NFSDBG_FACILITY NFSDBG_PNFS_LD

	static unsigned int dataserver_timeo = NFS4_DEF_DS_TIMEO;
	static unsigned int dataserver_retrans = NFS4_DEF_DS_RETRANS;

	void nfs4_ff_layout_put_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
	{
	if (mirror_ds)
	nfs4_put_deviceid_node(&mirror_ds->id_node);
	}

	void nfs4_ff_layout_free_deviceid(struct nfs4_ff_layout_ds *mirror_ds)
	{
	nfs4_print_deviceid(&mirror_ds->id_node.deviceid);
	nfs4_pnfs_ds_put(mirror_ds->ds);
	kfree_rcu(mirror_ds, id_node.rcu);
	}

	/* Decode opaque device data and construct new_ds using it */
	struct nfs4_ff_layout_ds *
	nfs4_ff_alloc_deviceid_node(struct nfs_server server, struct pnfs_device pdev,
	gfp_t gfp_flags)
	{
	struct xdr_stream stream;
	struct xdr_buf buf;
	struct page *scratch;
	struct list_head dsaddrs;
	struct nfs4_pnfs_ds_addr *da;
	struct nfs4_ff_layout_ds *new_ds = NULL;
	struct nfs4_ff_ds_version *ds_versions = NULL;
	u32 mp_count;
	u32 version_count;
	__be32 *p;
	int i, ret = -ENOMEM;

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

	new_ds = kzalloc(sizeof(struct nfs4_ff_layout_ds), gfp_flags);
	if (!new_ds)
	goto out_scratch;

	nfs4_init_deviceid_node(&new_ds->id_node,
	server,
	&pdev->dev_id);
	INIT_LIST_HEAD(&dsaddrs);

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

	/* multipath count */
	p = xdr_inline_decode(&stream, 4);
	if (unlikely(!p))
	goto out_err_drain_dsaddrs;
	mp_count = be32_to_cpup(p);
	dprintk("%s: multipath ds count %d\n", __func__, mp_count);

	for (i = 0; i < mp_count; i++) {
	/* multipath ds */
	da = nfs4_decode_mp_ds_addr(server->nfs_client->cl_net,
	&stream, gfp_flags);
	if (da)
	list_add_tail(&da->da_node, &dsaddrs);
	}
	if (list_empty(&dsaddrs)) {
	dprintk("%s: no suitable DS addresses found\n",
	__func__);
	ret = -ENOMEDIUM;
	goto out_err_drain_dsaddrs;
	}

	/* version count */
	p = xdr_inline_decode(&stream, 4);
	if (unlikely(!p))
	goto out_err_drain_dsaddrs;
	version_count = be32_to_cpup(p);
	dprintk("%s: version count %d\n", __func__, version_count);

	ds_versions = kzalloc(version_count * sizeof(struct nfs4_ff_ds_version),
	gfp_flags);
	if (!ds_versions)
	goto out_scratch;

	for (i = 0; i < version_count; i++) {
	/* 20 = version(4) + minor_version(4) + rsize(4) + wsize(4) +
	* tightly_coupled(4) */
	p = xdr_inline_decode(&stream, 20);
	if (unlikely(!p))
	goto out_err_drain_dsaddrs;
	ds_versions[i].version = be32_to_cpup(p++);
	ds_versions[i].minor_version = be32_to_cpup(p++);
	ds_versions[i].rsize = nfs_block_size(be32_to_cpup(p++), NULL);
	ds_versions[i].wsize = nfs_block_size(be32_to_cpup(p++), NULL);
	ds_versions[i].tightly_coupled = be32_to_cpup(p);

	if (ds_versions[i].rsize > NFS_MAX_FILE_IO_SIZE)
	ds_versions[i].rsize = NFS_MAX_FILE_IO_SIZE;
	if (ds_versions[i].wsize > NFS_MAX_FILE_IO_SIZE)
	ds_versions[i].wsize = NFS_MAX_FILE_IO_SIZE;

	if (ds_versions[i].version != 3 \|\| ds_versions[i].minor_version != 0) {
	dprintk("%s: [%d] unsupported ds version %d-%d\n", __func__,
	i, ds_versions[i].version,
	ds_versions[i].minor_version);
	ret = -EPROTONOSUPPORT;
	goto out_err_drain_dsaddrs;
	}

	dprintk("%s: [%d] vers %u minor_ver %u rsize %u wsize %u coupled %d\n",
	__func__, i, ds_versions[i].version,
	ds_versions[i].minor_version,
	ds_versions[i].rsize,
	ds_versions[i].wsize,
	ds_versions[i].tightly_coupled);
	}

	new_ds->ds_versions = ds_versions;
	new_ds->ds_versions_cnt = version_count;

	new_ds->ds = nfs4_pnfs_ds_add(&dsaddrs, gfp_flags);
	if (!new_ds->ds)
	goto out_err_drain_dsaddrs;

	/* If DS was already in cache, free ds addrs */
	while (!list_empty(&dsaddrs)) {
	da = list_first_entry(&dsaddrs,
	struct nfs4_pnfs_ds_addr,
	da_node);
	list_del_init(&da->da_node);
	kfree(da->da_remotestr);
	kfree(da);
	}

	__free_page(scratch);
	return new_ds;

	out_err_drain_dsaddrs:
	while (!list_empty(&dsaddrs)) {
	da = list_first_entry(&dsaddrs, struct nfs4_pnfs_ds_addr,
	da_node);
	list_del_init(&da->da_node);
	kfree(da->da_remotestr);
	kfree(da);
	}

	kfree(ds_versions);
	out_scratch:
	__free_page(scratch);
	out_err:
	kfree(new_ds);

	dprintk("%s ERROR: returning %d\n", __func__, ret);
	return NULL;
	}

	static u64
	end_offset(u64 start, u64 len)
	{
	u64 end;

	end = start + len;
	return end >= start ? end : NFS4_MAX_UINT64;
	}

	static void extend_ds_error(struct nfs4_ff_layout_ds_err *err,
	u64 offset, u64 length)
	{
	u64 end;

	end = max_t(u64, end_offset(err->offset, err->length),
	end_offset(offset, length));
	err->offset = min_t(u64, err->offset, offset);
	err->length = end - err->offset;
	}

	static bool ds_error_can_merge(struct nfs4_ff_layout_ds_err *err, u64 offset,
	u64 length, int status, enum nfs_opnum4 opnum,
	nfs4_stateid *stateid,
	struct nfs4_deviceid *deviceid)
	{
	return err->status == status && err->opnum == opnum &&
	nfs4_stateid_match(&err->stateid, stateid) &&
	!memcmp(&err->deviceid, deviceid, sizeof(*deviceid)) &&
	end_offset(err->offset, err->length) >= offset &&
	err->offset <= end_offset(offset, length);
	}

	static bool merge_ds_error(struct nfs4_ff_layout_ds_err *old,
	struct nfs4_ff_layout_ds_err *new)
	{
	if (!ds_error_can_merge(old, new->offset, new->length, new->status,
	new->opnum, &new->stateid, &new->deviceid))
	return false;

	extend_ds_error(old, new->offset, new->length);
	return true;
	}

	static bool
	ff_layout_add_ds_error_locked(struct nfs4_flexfile_layout *flo,
	struct nfs4_ff_layout_ds_err *dserr)
	{
	struct nfs4_ff_layout_ds_err *err;

	list_for_each_entry(err, &flo->error_list, list) {
	if (merge_ds_error(err, dserr)) {
	return true;
	}
	}

	list_add(&dserr->list, &flo->error_list);
	return false;
	}

	static bool
	ff_layout_update_ds_error(struct nfs4_flexfile_layout *flo, u64 offset,
	u64 length, int status, enum nfs_opnum4 opnum,
	nfs4_stateid stateid, struct nfs4_deviceid deviceid)
	{
	bool found = false;
	struct nfs4_ff_layout_ds_err *err;

	list_for_each_entry(err, &flo->error_list, list) {
	if (ds_error_can_merge(err, offset, length, status, opnum,
	stateid, deviceid)) {
	found = true;
	extend_ds_error(err, offset, length);
	break;
	}
	}

	return found;
	}

	int ff_layout_track_ds_error(struct nfs4_flexfile_layout *flo,
	struct nfs4_ff_layout_mirror *mirror, u64 offset,
	u64 length, int status, enum nfs_opnum4 opnum,
	gfp_t gfp_flags)
	{
	struct nfs4_ff_layout_ds_err *dserr;
	bool needfree;

	if (status == 0)
	return 0;

	if (mirror->mirror_ds == NULL)
	return -EINVAL;

	spin_lock(&flo->generic_hdr.plh_inode->i_lock);
	if (ff_layout_update_ds_error(flo, offset, length, status, opnum,
	&mirror->stateid,
	&mirror->mirror_ds->id_node.deviceid)) {
	spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
	return 0;
	}
	spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
	dserr = kmalloc(sizeof(*dserr), gfp_flags);
	if (!dserr)
	return -ENOMEM;

	INIT_LIST_HEAD(&dserr->list);
	dserr->offset = offset;
	dserr->length = length;
	dserr->status = status;
	dserr->opnum = opnum;
	nfs4_stateid_copy(&dserr->stateid, &mirror->stateid);
	memcpy(&dserr->deviceid, &mirror->mirror_ds->id_node.deviceid,
	NFS4_DEVICEID4_SIZE);

	spin_lock(&flo->generic_hdr.plh_inode->i_lock);
	needfree = ff_layout_add_ds_error_locked(flo, dserr);
	spin_unlock(&flo->generic_hdr.plh_inode->i_lock);
	if (needfree)
	kfree(dserr);

	return 0;
	}

	/* currently we only support AUTH_NONE and AUTH_SYS */
	static rpc_authflavor_t
	nfs4_ff_layout_choose_authflavor(struct nfs4_ff_layout_mirror *mirror)
	{
	if (mirror->uid == (u32)-1)
	return RPC_AUTH_NULL;
	return RPC_AUTH_UNIX;
	}

	/* fetch cred for NFSv3 DS */
	static int ff_layout_update_mirror_cred(struct nfs4_ff_layout_mirror *mirror,
	struct nfs4_pnfs_ds *ds)
	{
	if (ds->ds_clp && !mirror->cred &&
	mirror->mirror_ds->ds_versions[0].version == 3) {
	struct rpc_auth *auth = ds->ds_clp->cl_rpcclient->cl_auth;
	struct rpc_cred *cred;
	struct auth_cred acred = {
	.uid = make_kuid(&init_user_ns, mirror->uid),
	.gid = make_kgid(&init_user_ns, mirror->gid),
	};

	/* AUTH_NULL ignores acred */
	cred = auth->au_ops->lookup_cred(auth, &acred, 0);
	if (IS_ERR(cred)) {
	dprintk("%s: lookup_cred failed with %ld\n",
	__func__, PTR_ERR(cred));
	return PTR_ERR(cred);
	} else {
	if (cmpxchg(&mirror->cred, NULL, cred))
	put_rpccred(cred);
	}
	}
	return 0;
	}

	struct nfs_fh *
	nfs4_ff_layout_select_ds_fh(struct pnfs_layout_segment *lseg, u32 mirror_idx)
	{
	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, mirror_idx);
	struct nfs_fh *fh = NULL;
	struct nfs4_deviceid_node *devid;

	if (mirror == NULL \|\| mirror->mirror_ds == NULL \|\|
	mirror->mirror_ds->ds == NULL) {
	printk(KERN_ERR "NFS: %s: No data server for mirror offset index %d\n",
	__func__, mirror_idx);
	if (mirror && mirror->mirror_ds) {
	devid = &mirror->mirror_ds->id_node;
	pnfs_generic_mark_devid_invalid(devid);
	}
	goto out;
	}

	/* FIXME: For now assume there is only 1 version available for the DS */
	fh = &mirror->fh_versions[0];
	out:
	return fh;
	}

	/* Upon return, either ds is connected, or ds is NULL */
	struct nfs4_pnfs_ds *
	nfs4_ff_layout_prepare_ds(struct pnfs_layout_segment *lseg, u32 ds_idx,
	bool fail_return)
	{
	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
	struct nfs4_pnfs_ds *ds = NULL;
	struct nfs4_deviceid_node *devid;
	struct inode *ino = lseg->pls_layout->plh_inode;
	struct nfs_server *s = NFS_SERVER(ino);
	unsigned int max_payload;
	rpc_authflavor_t flavor;

	if (mirror == NULL \|\| mirror->mirror_ds == NULL \|\|
	mirror->mirror_ds->ds == NULL) {
	printk(KERN_ERR "NFS: %s: No data server for offset index %d\n",
	__func__, ds_idx);
	if (mirror && mirror->mirror_ds) {
	devid = &mirror->mirror_ds->id_node;
	pnfs_generic_mark_devid_invalid(devid);
	}
	goto out;
	}

	devid = &mirror->mirror_ds->id_node;
	if (ff_layout_test_devid_unavailable(devid))
	goto out;

	ds = mirror->mirror_ds->ds;
	/* matching smp_wmb() in _nfs4_pnfs_v3/4_ds_connect */
	smp_rmb();
	if (ds->ds_clp)
	goto out_update_creds;

	flavor = nfs4_ff_layout_choose_authflavor(mirror);

	/* FIXME: For now we assume the server sent only one version of NFS
	* to use for the DS.
	*/
	nfs4_pnfs_ds_connect(s, ds, devid, dataserver_timeo,
	dataserver_retrans,
	mirror->mirror_ds->ds_versions[0].version,
	mirror->mirror_ds->ds_versions[0].minor_version,
	flavor);

	/* connect success, check rsize/wsize limit */
	if (ds->ds_clp) {
	max_payload =
	nfs_block_size(rpc_max_payload(ds->ds_clp->cl_rpcclient),
	NULL);
	if (mirror->mirror_ds->ds_versions[0].rsize > max_payload)
	mirror->mirror_ds->ds_versions[0].rsize = max_payload;
	if (mirror->mirror_ds->ds_versions[0].wsize > max_payload)
	mirror->mirror_ds->ds_versions[0].wsize = max_payload;
	} else {
	ff_layout_track_ds_error(FF_LAYOUT_FROM_HDR(lseg->pls_layout),
	mirror, lseg->pls_range.offset,
	lseg->pls_range.length, NFS4ERR_NXIO,
	OP_ILLEGAL, GFP_NOIO);
	if (fail_return) {
	pnfs_error_mark_layout_for_return(ino, lseg);
	if (ff_layout_has_available_ds(lseg))
	pnfs_set_retry_layoutget(lseg->pls_layout);
	else
	pnfs_clear_retry_layoutget(lseg->pls_layout);

	} else {
	if (ff_layout_has_available_ds(lseg))
	set_bit(NFS_LAYOUT_RETURN_BEFORE_CLOSE,
	&lseg->pls_layout->plh_flags);
	else {
	pnfs_error_mark_layout_for_return(ino, lseg);
	pnfs_clear_retry_layoutget(lseg->pls_layout);
	}
	}
	}
	out_update_creds:
	if (ff_layout_update_mirror_cred(mirror, ds))
	ds = NULL;
	out:
	return ds;
	}

	struct rpc_cred *
	ff_layout_get_ds_cred(struct pnfs_layout_segment *lseg, u32 ds_idx,
	struct rpc_cred *mdscred)
	{
	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);
	struct rpc_cred *cred = ERR_PTR(-EINVAL);

	if (!nfs4_ff_layout_prepare_ds(lseg, ds_idx, true))
	goto out;

	if (mirror && mirror->cred)
	cred = mirror->cred;
	else
	cred = mdscred;
	out:
	return cred;
	}

	/**
	* Find or create a DS rpc client with th MDS server rpc client auth flavor
	* in the nfs_client cl_ds_clients list.
	*/
	struct rpc_clnt *
	nfs4_ff_find_or_create_ds_client(struct pnfs_layout_segment *lseg, u32 ds_idx,
	struct nfs_client ds_clp, struct inode inode)
	{
	struct nfs4_ff_layout_mirror *mirror = FF_LAYOUT_COMP(lseg, ds_idx);

	switch (mirror->mirror_ds->ds_versions[0].version) {
	case 3:
	/* For NFSv3 DS, flavor is set when creating DS connections */
	return ds_clp->cl_rpcclient;
	case 4:
	return nfs4_find_or_create_ds_client(ds_clp, inode);
	default:
	BUG();
	}
	}

	static bool is_range_intersecting(u64 offset1, u64 length1,
	u64 offset2, u64 length2)
	{
	u64 end1 = end_offset(offset1, length1);
	u64 end2 = end_offset(offset2, length2);

	return (end1 == NFS4_MAX_UINT64 \|\| end1 > offset2) &&
	(end2 == NFS4_MAX_UINT64 \|\| end2 > offset1);
	}

	/* called with inode i_lock held */
	int ff_layout_encode_ds_ioerr(struct nfs4_flexfile_layout *flo,
	struct xdr_stream xdr, int count,
	const struct pnfs_layout_range *range)
	{
	struct nfs4_ff_layout_ds_err err, n;
	__be32 *p;

	list_for_each_entry_safe(err, n, &flo->error_list, list) {
	if (!is_range_intersecting(err->offset, err->length,
	range->offset, range->length))
	continue;
	/* offset(8) + length(8) + stateid(NFS4_STATEID_SIZE)
	* + deviceid(NFS4_DEVICEID4_SIZE) + status(4) + opnum(4)
	*/
	p = xdr_reserve_space(xdr,
	24 + NFS4_STATEID_SIZE + NFS4_DEVICEID4_SIZE);
	if (unlikely(!p))
	return -ENOBUFS;
	p = xdr_encode_hyper(p, err->offset);
	p = xdr_encode_hyper(p, err->length);
	p = xdr_encode_opaque_fixed(p, &err->stateid,
	NFS4_STATEID_SIZE);
	p = xdr_encode_opaque_fixed(p, &err->deviceid,
	NFS4_DEVICEID4_SIZE);
	*p++ = cpu_to_be32(err->status);
	*p++ = cpu_to_be32(err->opnum);
	*count += 1;
	list_del(&err->list);
	dprintk("%s: offset %llu length %llu status %d op %d count %d\n",
	__func__, err->offset, err->length, err->status,
	err->opnum, *count);
	kfree(err);
	}

	return 0;
	}

	bool ff_layout_has_available_ds(struct pnfs_layout_segment *lseg)
	{
	struct nfs4_ff_layout_mirror *mirror;
	struct nfs4_deviceid_node *devid;
	int idx;

	for (idx = 0; idx < FF_LAYOUT_MIRROR_COUNT(lseg); idx++) {
	mirror = FF_LAYOUT_COMP(lseg, idx);
	if (mirror && mirror->mirror_ds) {
	devid = &mirror->mirror_ds->id_node;
	if (!ff_layout_test_devid_unavailable(devid))
	return true;
	}
	}

	return false;
	}

	module_param(dataserver_retrans, uint, 0644);
	MODULE_PARM_DESC(dataserver_retrans, "The number of times the NFSv4.1 client "
	"retries a request before it attempts further "
	" recovery action.");
	module_param(dataserver_timeo, uint, 0644);
	MODULE_PARM_DESC(dataserver_timeo, "The time (in tenths of a second) the "
	"NFSv4.1 client waits for a response from a "
	" data server before it retries an NFS request.");