fs/nfs/pnfs_dev.c - third_party/linux - Git at Google

 /*
  *  Device operations for the pnfs client.
  *
  *  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/export.h>
 #include <linux/nfs_fs.h>
 #include "nfs4session.h"
 #include "internal.h"
 #include "pnfs.h"

 #define NFSDBG_FACILITY		NFSDBG_PNFS

 /*
  * Device ID RCU cache. A device ID is unique per server and layout type.
  */
 #define NFS4_DEVICE_ID_HASH_BITS	5
 #define NFS4_DEVICE_ID_HASH_SIZE	(1 << NFS4_DEVICE_ID_HASH_BITS)
 #define NFS4_DEVICE_ID_HASH_MASK	(NFS4_DEVICE_ID_HASH_SIZE - 1)


 static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
 static DEFINE_SPINLOCK(nfs4_deviceid_lock);

 #ifdef NFS_DEBUG
 void
 nfs4_print_deviceid(const struct nfs4_deviceid *id)
 {
 	u32 *p = (u32 *)id;

 	dprintk("%s: device id= [%x%x%x%x]\n", __func__,
 		p[0], p[1], p[2], p[3]);
 }
 EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
 #endif

 static inline u32
 nfs4_deviceid_hash(const struct nfs4_deviceid *id)
 {
 	unsigned char *cptr = (unsigned char *)id->data;
 	unsigned int nbytes = NFS4_DEVICEID4_SIZE;
 	u32 x = 0;

 	while (nbytes--) {
 		x *= 37;
 		x += *cptr++;
 	}
 	return x & NFS4_DEVICE_ID_HASH_MASK;
 }

 static struct nfs4_deviceid_node *
 _lookup_deviceid(const struct pnfs_layoutdriver_type *ld,
 		 const struct nfs_client *clp, const struct nfs4_deviceid *id,
 		 long hash)
 {
 	struct nfs4_deviceid_node *d;

 	hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[hash], node)
 		if (d->ld == ld && d->nfs_client == clp &&
 		    !memcmp(&d->deviceid, id, sizeof(*id))) {
 			if (atomic_read(&d->ref))
 				return d;
 			else
 				continue;
 		}
 	return NULL;
 }

 static struct nfs4_deviceid_node *
 nfs4_get_device_info(struct nfs_server *server,
 		const struct nfs4_deviceid *dev_id,
 		const struct cred *cred, gfp_t gfp_flags)
 {
 	struct nfs4_deviceid_node *d = NULL;
 	struct pnfs_device *pdev = NULL;
 	struct page **pages = NULL;
 	u32 max_resp_sz;
 	int max_pages;
 	int rc, i;

 	/*
 	 * 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;
 	if (server->pnfs_curr_ld->max_deviceinfo_size &&
 	    server->pnfs_curr_ld->max_deviceinfo_size < max_resp_sz)
 		max_resp_sz = server->pnfs_curr_ld->max_deviceinfo_size;
 	max_pages = nfs_page_array_len(0, max_resp_sz);
 	dprintk("%s: server %p max_resp_sz %u max_pages %d\n",
 		__func__, server, max_resp_sz, max_pages);

 	pdev = kzalloc(sizeof(*pdev), gfp_flags);
 	if (!pdev)
 		return NULL;

 	pages = kcalloc(max_pages, sizeof(struct page *), gfp_flags);
 	if (!pages)
 		goto out_free_pdev;

 	for (i = 0; i < max_pages; i++) {
 		pages[i] = alloc_page(gfp_flags);
 		if (!pages[i])
 			goto out_free_pages;
 	}

 	memcpy(&pdev->dev_id, dev_id, sizeof(*dev_id));
 	pdev->layout_type = server->pnfs_curr_ld->id;
 	pdev->pages = pages;
 	pdev->pgbase = 0;
 	pdev->pglen = max_resp_sz;
 	pdev->mincount = 0;
 	pdev->maxcount = max_resp_sz - nfs41_maxgetdevinfo_overhead;

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

 	/*
 	 * Found new device, need to decode it and then add it to the
 	 * list of known devices for this mountpoint.
 	 */
 	d = server->pnfs_curr_ld->alloc_deviceid_node(server, pdev,
 			gfp_flags);
 	if (d && pdev->nocache)
 		set_bit(NFS_DEVICEID_NOCACHE, &d->flags);

 out_free_pages:
 	while (--i >= 0)
 		__free_page(pages[i]);
 	kfree(pages);
 out_free_pdev:
 	kfree(pdev);
 	dprintk("<-- %s d %p\n", __func__, d);
 	return d;
 }

 /*
  * Lookup a deviceid in cache and get a reference count on it if found
  *
  * @clp nfs_client associated with deviceid
  * @id deviceid to look up
  */
 static struct nfs4_deviceid_node *
 __nfs4_find_get_deviceid(struct nfs_server *server,
 		const struct nfs4_deviceid *id, long hash)
 {
 	struct nfs4_deviceid_node *d;

 	rcu_read_lock();
 	d = _lookup_deviceid(server->pnfs_curr_ld, server->nfs_client, id,
 			hash);
 	if (d != NULL && !atomic_inc_not_zero(&d->ref))
 		d = NULL;
 	rcu_read_unlock();
 	return d;
 }

 struct nfs4_deviceid_node *
 nfs4_find_get_deviceid(struct nfs_server *server,
 		const struct nfs4_deviceid *id, const struct cred *cred,
 		gfp_t gfp_mask)
 {
 	long hash = nfs4_deviceid_hash(id);
 	struct nfs4_deviceid_node *d, *new;

 	d = __nfs4_find_get_deviceid(server, id, hash);
 	if (d)
 		return d;

 	new = nfs4_get_device_info(server, id, cred, gfp_mask);
 	if (!new)
 		return new;

 	spin_lock(&nfs4_deviceid_lock);
 	d = __nfs4_find_get_deviceid(server, id, hash);
 	if (d) {
 		spin_unlock(&nfs4_deviceid_lock);
 		server->pnfs_curr_ld->free_deviceid_node(new);
 		return d;
 	}
 	hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
 	atomic_inc(&new->ref);
 	spin_unlock(&nfs4_deviceid_lock);

 	return new;
 }
 EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);

 /*
  * Remove a deviceid from cache
  *
  * @clp nfs_client associated with deviceid
  * @id the deviceid to unhash
  *
  * @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
  */
 void
 nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
 			 const struct nfs_client *clp, const struct nfs4_deviceid *id)
 {
 	struct nfs4_deviceid_node *d;

 	spin_lock(&nfs4_deviceid_lock);
 	rcu_read_lock();
 	d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
 	rcu_read_unlock();
 	if (!d) {
 		spin_unlock(&nfs4_deviceid_lock);
 		return;
 	}
 	hlist_del_init_rcu(&d->node);
 	clear_bit(NFS_DEVICEID_NOCACHE, &d->flags);
 	spin_unlock(&nfs4_deviceid_lock);

 	/* balance the initial ref set in pnfs_insert_deviceid */
 	nfs4_put_deviceid_node(d);
 }
 EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);

 void
 nfs4_init_deviceid_node(struct nfs4_deviceid_node *d, struct nfs_server *server,
 			const struct nfs4_deviceid *id)
 {
 	INIT_HLIST_NODE(&d->node);
 	INIT_HLIST_NODE(&d->tmpnode);
 	d->ld = server->pnfs_curr_ld;
 	d->nfs_client = server->nfs_client;
 	d->flags = 0;
 	d->deviceid = *id;
 	atomic_set(&d->ref, 1);
 }
 EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);

 /*
  * Dereference a deviceid node and delete it when its reference count drops
  * to zero.
  *
  * @d deviceid node to put
  *
  * return true iff the node was deleted
  * Note that since the test for d->ref == 0 is sufficient to establish
  * that the node is no longer hashed in the global device id cache.
  */
 bool
 nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
 {
 	if (test_bit(NFS_DEVICEID_NOCACHE, &d->flags)) {
 		if (atomic_add_unless(&d->ref, -1, 2))
 			return false;
 		nfs4_delete_deviceid(d->ld, d->nfs_client, &d->deviceid);
 	}
 	if (!atomic_dec_and_test(&d->ref))
 		return false;
 	d->ld->free_deviceid_node(d);
 	return true;
 }
 EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);

 void
 nfs4_mark_deviceid_available(struct nfs4_deviceid_node *node)
 {
 	if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
 		clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
 		smp_mb__after_atomic();
 	}
 }
 EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_available);

 void
 nfs4_mark_deviceid_unavailable(struct nfs4_deviceid_node *node)
 {
 	node->timestamp_unavailable = jiffies;
 	smp_mb__before_atomic();
 	set_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
 	smp_mb__after_atomic();
 }
 EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_unavailable);

 bool
 nfs4_test_deviceid_unavailable(struct nfs4_deviceid_node *node)
 {
 	if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
 		unsigned long start, end;

 		end = jiffies;
 		start = end - PNFS_DEVICE_RETRY_TIMEOUT;
 		if (time_in_range(node->timestamp_unavailable, start, end))
 			return true;
 		clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
 		smp_mb__after_atomic();
 	}
 	return false;
 }
 EXPORT_SYMBOL_GPL(nfs4_test_deviceid_unavailable);

 static void
 _deviceid_purge_client(const struct nfs_client *clp, long hash)
 {
 	struct nfs4_deviceid_node *d;
 	HLIST_HEAD(tmp);

 	spin_lock(&nfs4_deviceid_lock);
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[hash], node)
 		if (d->nfs_client == clp && atomic_read(&d->ref)) {
 			hlist_del_init_rcu(&d->node);
 			hlist_add_head(&d->tmpnode, &tmp);
 			clear_bit(NFS_DEVICEID_NOCACHE, &d->flags);
 		}
 	rcu_read_unlock();
 	spin_unlock(&nfs4_deviceid_lock);

 	if (hlist_empty(&tmp))
 		return;

 	while (!hlist_empty(&tmp)) {
 		d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
 		hlist_del(&d->tmpnode);
 		nfs4_put_deviceid_node(d);
 	}
 }

 void
 nfs4_deviceid_purge_client(const struct nfs_client *clp)
 {
 	long h;

 	if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
 		return;
 	for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
 		_deviceid_purge_client(clp, h);
 }

 /*
  * Stop use of all deviceids associated with an nfs_client
  */
 void
 nfs4_deviceid_mark_client_invalid(struct nfs_client *clp)
 {
 	struct nfs4_deviceid_node *d;
 	int i;

 	rcu_read_lock();
 	for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE; i ++){
 		hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[i], node)
 			if (d->nfs_client == clp)
 				set_bit(NFS_DEVICEID_INVALID, &d->flags);
 	}
 	rcu_read_unlock();
 }
	/*
	* Device operations for the pnfs client.
	*
	* 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/export.h>
	#include <linux/nfs_fs.h>
	#include "nfs4session.h"
	#include "internal.h"
	#include "pnfs.h"

	#define NFSDBG_FACILITY NFSDBG_PNFS

	/*
	* Device ID RCU cache. A device ID is unique per server and layout type.
	*/
	#define NFS4_DEVICE_ID_HASH_BITS 5
	#define NFS4_DEVICE_ID_HASH_SIZE (1 << NFS4_DEVICE_ID_HASH_BITS)
	#define NFS4_DEVICE_ID_HASH_MASK (NFS4_DEVICE_ID_HASH_SIZE - 1)


	static struct hlist_head nfs4_deviceid_cache[NFS4_DEVICE_ID_HASH_SIZE];
	static DEFINE_SPINLOCK(nfs4_deviceid_lock);

	#ifdef NFS_DEBUG
	void
	nfs4_print_deviceid(const struct nfs4_deviceid *id)
	{
	u32 p = (u32 )id;

	dprintk("%s: device id= [%x%x%x%x]\n", __func__,
	p[0], p[1], p[2], p[3]);
	}
	EXPORT_SYMBOL_GPL(nfs4_print_deviceid);
	#endif

	static inline u32
	nfs4_deviceid_hash(const struct nfs4_deviceid *id)
	{
	unsigned char cptr = (unsigned char )id->data;
	unsigned int nbytes = NFS4_DEVICEID4_SIZE;
	u32 x = 0;

	while (nbytes--) {
	x *= 37;
	x += *cptr++;
	}
	return x & NFS4_DEVICE_ID_HASH_MASK;
	}

	static struct nfs4_deviceid_node *
	_lookup_deviceid(const struct pnfs_layoutdriver_type *ld,
	const struct nfs_client clp, const struct nfs4_deviceid id,
	long hash)
	{
	struct nfs4_deviceid_node *d;

	hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[hash], node)
	if (d->ld == ld && d->nfs_client == clp &&
	!memcmp(&d->deviceid, id, sizeof(*id))) {
	if (atomic_read(&d->ref))
	return d;
	else
	continue;
	}
	return NULL;
	}

	static struct nfs4_deviceid_node *
	nfs4_get_device_info(struct nfs_server *server,
	const struct nfs4_deviceid *dev_id,
	const struct cred *cred, gfp_t gfp_flags)
	{
	struct nfs4_deviceid_node *d = NULL;
	struct pnfs_device *pdev = NULL;
	struct page **pages = NULL;
	u32 max_resp_sz;
	int max_pages;
	int rc, i;

	/*
	* 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;
	if (server->pnfs_curr_ld->max_deviceinfo_size &&
	server->pnfs_curr_ld->max_deviceinfo_size < max_resp_sz)
	max_resp_sz = server->pnfs_curr_ld->max_deviceinfo_size;
	max_pages = nfs_page_array_len(0, max_resp_sz);
	dprintk("%s: server %p max_resp_sz %u max_pages %d\n",
	__func__, server, max_resp_sz, max_pages);

	pdev = kzalloc(sizeof(*pdev), gfp_flags);
	if (!pdev)
	return NULL;

	pages = kcalloc(max_pages, sizeof(struct page *), gfp_flags);
	if (!pages)
	goto out_free_pdev;

	for (i = 0; i < max_pages; i++) {
	pages[i] = alloc_page(gfp_flags);
	if (!pages[i])
	goto out_free_pages;
	}

	memcpy(&pdev->dev_id, dev_id, sizeof(*dev_id));
	pdev->layout_type = server->pnfs_curr_ld->id;
	pdev->pages = pages;
	pdev->pgbase = 0;
	pdev->pglen = max_resp_sz;
	pdev->mincount = 0;
	pdev->maxcount = max_resp_sz - nfs41_maxgetdevinfo_overhead;

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

	/*
	* Found new device, need to decode it and then add it to the
	* list of known devices for this mountpoint.
	*/
	d = server->pnfs_curr_ld->alloc_deviceid_node(server, pdev,
	gfp_flags);
	if (d && pdev->nocache)
	set_bit(NFS_DEVICEID_NOCACHE, &d->flags);

	out_free_pages:
	while (--i >= 0)
	__free_page(pages[i]);
	kfree(pages);
	out_free_pdev:
	kfree(pdev);
	dprintk("<-- %s d %p\n", __func__, d);
	return d;
	}

	/*
	* Lookup a deviceid in cache and get a reference count on it if found
	*
	* @clp nfs_client associated with deviceid
	* @id deviceid to look up
	*/
	static struct nfs4_deviceid_node *
	__nfs4_find_get_deviceid(struct nfs_server *server,
	const struct nfs4_deviceid *id, long hash)
	{
	struct nfs4_deviceid_node *d;

	rcu_read_lock();
	d = _lookup_deviceid(server->pnfs_curr_ld, server->nfs_client, id,
	hash);
	if (d != NULL && !atomic_inc_not_zero(&d->ref))
	d = NULL;
	rcu_read_unlock();
	return d;
	}

	struct nfs4_deviceid_node *
	nfs4_find_get_deviceid(struct nfs_server *server,
	const struct nfs4_deviceid id, const struct cred cred,
	gfp_t gfp_mask)
	{
	long hash = nfs4_deviceid_hash(id);
	struct nfs4_deviceid_node d, new;

	d = __nfs4_find_get_deviceid(server, id, hash);
	if (d)
	return d;

	new = nfs4_get_device_info(server, id, cred, gfp_mask);
	if (!new)
	return new;

	spin_lock(&nfs4_deviceid_lock);
	d = __nfs4_find_get_deviceid(server, id, hash);
	if (d) {
	spin_unlock(&nfs4_deviceid_lock);
	server->pnfs_curr_ld->free_deviceid_node(new);
	return d;
	}
	hlist_add_head_rcu(&new->node, &nfs4_deviceid_cache[hash]);
	atomic_inc(&new->ref);
	spin_unlock(&nfs4_deviceid_lock);

	return new;
	}
	EXPORT_SYMBOL_GPL(nfs4_find_get_deviceid);

	/*
	* Remove a deviceid from cache
	*
	* @clp nfs_client associated with deviceid
	* @id the deviceid to unhash
	*
	* @ret the unhashed node, if found and dereferenced to zero, NULL otherwise.
	*/
	void
	nfs4_delete_deviceid(const struct pnfs_layoutdriver_type *ld,
	const struct nfs_client clp, const struct nfs4_deviceid id)
	{
	struct nfs4_deviceid_node *d;

	spin_lock(&nfs4_deviceid_lock);
	rcu_read_lock();
	d = _lookup_deviceid(ld, clp, id, nfs4_deviceid_hash(id));
	rcu_read_unlock();
	if (!d) {
	spin_unlock(&nfs4_deviceid_lock);
	return;
	}
	hlist_del_init_rcu(&d->node);
	clear_bit(NFS_DEVICEID_NOCACHE, &d->flags);
	spin_unlock(&nfs4_deviceid_lock);

	/* balance the initial ref set in pnfs_insert_deviceid */
	nfs4_put_deviceid_node(d);
	}
	EXPORT_SYMBOL_GPL(nfs4_delete_deviceid);

	void
	nfs4_init_deviceid_node(struct nfs4_deviceid_node d, struct nfs_server server,
	const struct nfs4_deviceid *id)
	{
	INIT_HLIST_NODE(&d->node);
	INIT_HLIST_NODE(&d->tmpnode);
	d->ld = server->pnfs_curr_ld;
	d->nfs_client = server->nfs_client;
	d->flags = 0;
	d->deviceid = *id;
	atomic_set(&d->ref, 1);
	}
	EXPORT_SYMBOL_GPL(nfs4_init_deviceid_node);

	/*
	* Dereference a deviceid node and delete it when its reference count drops
	* to zero.
	*
	* @d deviceid node to put
	*
	* return true iff the node was deleted
	* Note that since the test for d->ref == 0 is sufficient to establish
	* that the node is no longer hashed in the global device id cache.
	*/
	bool
	nfs4_put_deviceid_node(struct nfs4_deviceid_node *d)
	{
	if (test_bit(NFS_DEVICEID_NOCACHE, &d->flags)) {
	if (atomic_add_unless(&d->ref, -1, 2))
	return false;
	nfs4_delete_deviceid(d->ld, d->nfs_client, &d->deviceid);
	}
	if (!atomic_dec_and_test(&d->ref))
	return false;
	d->ld->free_deviceid_node(d);
	return true;
	}
	EXPORT_SYMBOL_GPL(nfs4_put_deviceid_node);

	void
	nfs4_mark_deviceid_available(struct nfs4_deviceid_node *node)
	{
	if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
	clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
	smp_mb__after_atomic();
	}
	}
	EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_available);

	void
	nfs4_mark_deviceid_unavailable(struct nfs4_deviceid_node *node)
	{
	node->timestamp_unavailable = jiffies;
	smp_mb__before_atomic();
	set_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
	smp_mb__after_atomic();
	}
	EXPORT_SYMBOL_GPL(nfs4_mark_deviceid_unavailable);

	bool
	nfs4_test_deviceid_unavailable(struct nfs4_deviceid_node *node)
	{
	if (test_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags)) {
	unsigned long start, end;

	end = jiffies;
	start = end - PNFS_DEVICE_RETRY_TIMEOUT;
	if (time_in_range(node->timestamp_unavailable, start, end))
	return true;
	clear_bit(NFS_DEVICEID_UNAVAILABLE, &node->flags);
	smp_mb__after_atomic();
	}
	return false;
	}
	EXPORT_SYMBOL_GPL(nfs4_test_deviceid_unavailable);

	static void
	_deviceid_purge_client(const struct nfs_client *clp, long hash)
	{
	struct nfs4_deviceid_node *d;
	HLIST_HEAD(tmp);

	spin_lock(&nfs4_deviceid_lock);
	rcu_read_lock();
	hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[hash], node)
	if (d->nfs_client == clp && atomic_read(&d->ref)) {
	hlist_del_init_rcu(&d->node);
	hlist_add_head(&d->tmpnode, &tmp);
	clear_bit(NFS_DEVICEID_NOCACHE, &d->flags);
	}
	rcu_read_unlock();
	spin_unlock(&nfs4_deviceid_lock);

	if (hlist_empty(&tmp))
	return;

	while (!hlist_empty(&tmp)) {
	d = hlist_entry(tmp.first, struct nfs4_deviceid_node, tmpnode);
	hlist_del(&d->tmpnode);
	nfs4_put_deviceid_node(d);
	}
	}

	void
	nfs4_deviceid_purge_client(const struct nfs_client *clp)
	{
	long h;

	if (!(clp->cl_exchange_flags & EXCHGID4_FLAG_USE_PNFS_MDS))
	return;
	for (h = 0; h < NFS4_DEVICE_ID_HASH_SIZE; h++)
	_deviceid_purge_client(clp, h);
	}

	/*
	* Stop use of all deviceids associated with an nfs_client
	*/
	void
	nfs4_deviceid_mark_client_invalid(struct nfs_client *clp)
	{
	struct nfs4_deviceid_node *d;
	int i;

	rcu_read_lock();
	for (i = 0; i < NFS4_DEVICE_ID_HASH_SIZE; i ++){
	hlist_for_each_entry_rcu(d, &nfs4_deviceid_cache[i], node)
	if (d->nfs_client == clp)
	set_bit(NFS_DEVICEID_INVALID, &d->flags);
	}
	rcu_read_unlock();
	}