fs/nfs/delegation.c - pub/scm/linux/kernel/git/joro/linux - Git at Google

 /*
  * linux/fs/nfs/delegation.c
  *
  * Copyright (C) 2004 Trond Myklebust
  *
  * NFS file delegation management
  *
  */
 #include <linux/completion.h>
 #include <linux/kthread.h>
 #include <linux/module.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/smp_lock.h>
 #include <linux/spinlock.h>

 #include <linux/nfs4.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfs_xdr.h>

 #include "nfs4_fs.h"
 #include "delegation.h"
 #include "internal.h"

 static void nfs_do_free_delegation(struct nfs_delegation *delegation)
 {
 	if (delegation->cred)
 		put_rpccred(delegation->cred);
 	kfree(delegation);
 }

 static void nfs_free_delegation_callback(struct rcu_head *head)
 {
 	struct nfs_delegation *delegation = container_of(head, struct nfs_delegation, rcu);

 	nfs_do_free_delegation(delegation);
 }

 static void nfs_free_delegation(struct nfs_delegation *delegation)
 {
 	call_rcu(&delegation->rcu, nfs_free_delegation_callback);
 }

 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
 {
 	set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
 }

 int nfs_have_delegation(struct inode *inode, fmode_t flags)
 {
 	struct nfs_delegation *delegation;
 	int ret = 0;

 	flags &= FMODE_READ|FMODE_WRITE;
 	rcu_read_lock();
 	delegation = rcu_dereference(NFS_I(inode)->delegation);
 	if (delegation != NULL && (delegation->type & flags) == flags) {
 		nfs_mark_delegation_referenced(delegation);
 		ret = 1;
 	}
 	rcu_read_unlock();
 	return ret;
 }

 static int nfs_delegation_claim_locks(struct nfs_open_context *ctx, struct nfs4_state *state)
 {
 	struct inode *inode = state->inode;
 	struct file_lock *fl;
 	int status = 0;

 	if (inode->i_flock == NULL)
 		goto out;

 	/* Protect inode->i_flock using the BKL */
 	lock_kernel();
 	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
 		if (!(fl->fl_flags & (FL_POSIX|FL_FLOCK)))
 			continue;
 		if (nfs_file_open_context(fl->fl_file) != ctx)
 			continue;
 		unlock_kernel();
 		status = nfs4_lock_delegation_recall(state, fl);
 		if (status < 0)
 			goto out;
 		lock_kernel();
 	}
 	unlock_kernel();
 out:
 	return status;
 }

 static int nfs_delegation_claim_opens(struct inode *inode, const nfs4_stateid *stateid)
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_open_context *ctx;
 	struct nfs4_state *state;
 	int err;

 again:
 	spin_lock(&inode->i_lock);
 	list_for_each_entry(ctx, &nfsi->open_files, list) {
 		state = ctx->state;
 		if (state == NULL)
 			continue;
 		if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
 			continue;
 		if (memcmp(state->stateid.data, stateid->data, sizeof(state->stateid.data)) != 0)
 			continue;
 		get_nfs_open_context(ctx);
 		spin_unlock(&inode->i_lock);
 		err = nfs4_open_delegation_recall(ctx, state, stateid);
 		if (err >= 0)
 			err = nfs_delegation_claim_locks(ctx, state);
 		put_nfs_open_context(ctx);
 		if (err != 0)
 			return err;
 		goto again;
 	}
 	spin_unlock(&inode->i_lock);
 	return 0;
 }

 /*
  * Set up a delegation on an inode
  */
 void nfs_inode_reclaim_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 {
 	struct nfs_delegation *delegation;
 	struct rpc_cred *oldcred = NULL;

 	rcu_read_lock();
 	delegation = rcu_dereference(NFS_I(inode)->delegation);
 	if (delegation != NULL) {
 		spin_lock(&delegation->lock);
 		if (delegation->inode != NULL) {
 			memcpy(delegation->stateid.data, res->delegation.data,
 			       sizeof(delegation->stateid.data));
 			delegation->type = res->delegation_type;
 			delegation->maxsize = res->maxsize;
 			oldcred = delegation->cred;
 			delegation->cred = get_rpccred(cred);
 			clear_bit(NFS_DELEGATION_NEED_RECLAIM,
 				  &delegation->flags);
 			NFS_I(inode)->delegation_state = delegation->type;
 			spin_unlock(&delegation->lock);
 			put_rpccred(oldcred);
 			rcu_read_unlock();
 		} else {
 			/* We appear to have raced with a delegation return. */
 			spin_unlock(&delegation->lock);
 			rcu_read_unlock();
 			nfs_inode_set_delegation(inode, cred, res);
 		}
 	} else {
 		rcu_read_unlock();
 	}
 }

 static int nfs_do_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 {
 	int res = 0;

 	res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
 	nfs_free_delegation(delegation);
 	return res;
 }

 static struct inode *nfs_delegation_grab_inode(struct nfs_delegation *delegation)
 {
 	struct inode *inode = NULL;

 	spin_lock(&delegation->lock);
 	if (delegation->inode != NULL)
 		inode = igrab(delegation->inode);
 	spin_unlock(&delegation->lock);
 	return inode;
 }

 static struct nfs_delegation *nfs_detach_delegation_locked(struct nfs_inode *nfsi,
 							   const nfs4_stateid *stateid,
 							   struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation =
 		rcu_dereference_protected(nfsi->delegation,
 					  lockdep_is_held(&clp->cl_lock));

 	if (delegation == NULL)
 		goto nomatch;
 	spin_lock(&delegation->lock);
 	if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
 				sizeof(delegation->stateid.data)) != 0)
 		goto nomatch_unlock;
 	list_del_rcu(&delegation->super_list);
 	delegation->inode = NULL;
 	nfsi->delegation_state = 0;
 	rcu_assign_pointer(nfsi->delegation, NULL);
 	spin_unlock(&delegation->lock);
 	return delegation;
 nomatch_unlock:
 	spin_unlock(&delegation->lock);
 nomatch:
 	return NULL;
 }

 /*
  * Set up a delegation on an inode
  */
 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 {
 	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_delegation *delegation, *old_delegation;
 	struct nfs_delegation *freeme = NULL;
 	int status = 0;

 	delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
 	if (delegation == NULL)
 		return -ENOMEM;
 	memcpy(delegation->stateid.data, res->delegation.data,
 			sizeof(delegation->stateid.data));
 	delegation->type = res->delegation_type;
 	delegation->maxsize = res->maxsize;
 	delegation->change_attr = nfsi->change_attr;
 	delegation->cred = get_rpccred(cred);
 	delegation->inode = inode;
 	delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
 	spin_lock_init(&delegation->lock);

 	spin_lock(&clp->cl_lock);
 	old_delegation = rcu_dereference_protected(nfsi->delegation,
 						   lockdep_is_held(&clp->cl_lock));
 	if (old_delegation != NULL) {
 		if (memcmp(&delegation->stateid, &old_delegation->stateid,
 					sizeof(old_delegation->stateid)) == 0 &&
 				delegation->type == old_delegation->type) {
 			goto out;
 		}
 		/*
 		 * Deal with broken servers that hand out two
 		 * delegations for the same file.
 		 */
 		dfprintk(FILE, "%s: server %s handed out "
 				"a duplicate delegation!\n",
 				__func__, clp->cl_hostname);
 		if (delegation->type <= old_delegation->type) {
 			freeme = delegation;
 			delegation = NULL;
 			goto out;
 		}
 		freeme = nfs_detach_delegation_locked(nfsi, NULL, clp);
 	}
 	list_add_rcu(&delegation->super_list, &clp->cl_delegations);
 	nfsi->delegation_state = delegation->type;
 	rcu_assign_pointer(nfsi->delegation, delegation);
 	delegation = NULL;

 	/* Ensure we revalidate the attributes and page cache! */
 	spin_lock(&inode->i_lock);
 	nfsi->cache_validity |= NFS_INO_REVAL_FORCED;
 	spin_unlock(&inode->i_lock);

 out:
 	spin_unlock(&clp->cl_lock);
 	if (delegation != NULL)
 		nfs_free_delegation(delegation);
 	if (freeme != NULL)
 		nfs_do_return_delegation(inode, freeme, 0);
 	return status;
 }

 /* Sync all data to disk upon delegation return */
 static void nfs_msync_inode(struct inode *inode)
 {
 	filemap_fdatawrite(inode->i_mapping);
 	nfs_wb_all(inode);
 	filemap_fdatawait(inode->i_mapping);
 }

 /*
  * Basic procedure for returning a delegation to the server
  */
 static int __nfs_inode_return_delegation(struct inode *inode, struct nfs_delegation *delegation, int issync)
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
 	int err;

 	/*
 	 * Guard against new delegated open/lock/unlock calls and against
 	 * state recovery
 	 */
 	down_write(&nfsi->rwsem);
 	err = nfs_delegation_claim_opens(inode, &delegation->stateid);
 	up_write(&nfsi->rwsem);
 	if (err)
 		goto out;

 	err = nfs_do_return_delegation(inode, delegation, issync);
 out:
 	return err;
 }

 /*
  * Return all delegations that have been marked for return
  */
 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation;
 	struct inode *inode;
 	int err = 0;

 restart:
 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
 		if (!test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
 			continue;
 		inode = nfs_delegation_grab_inode(delegation);
 		if (inode == NULL)
 			continue;
 		spin_lock(&clp->cl_lock);
 		delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL, clp);
 		spin_unlock(&clp->cl_lock);
 		rcu_read_unlock();
 		if (delegation != NULL) {
 			filemap_flush(inode->i_mapping);
 			err = __nfs_inode_return_delegation(inode, delegation, 0);
 		}
 		iput(inode);
 		if (!err)
 			goto restart;
 		set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 		return err;
 	}
 	rcu_read_unlock();
 	return 0;
 }

 /*
  * This function returns the delegation without reclaiming opens
  * or protecting against delegation reclaims.
  * It is therefore really only safe to be called from
  * nfs4_clear_inode()
  */
 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 {
 	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_delegation *delegation;

 	if (rcu_access_pointer(nfsi->delegation) != NULL) {
 		spin_lock(&clp->cl_lock);
 		delegation = nfs_detach_delegation_locked(nfsi, NULL, clp);
 		spin_unlock(&clp->cl_lock);
 		if (delegation != NULL)
 			nfs_do_return_delegation(inode, delegation, 0);
 	}
 }

 int nfs_inode_return_delegation(struct inode *inode)
 {
 	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_delegation *delegation;
 	int err = 0;

 	if (rcu_access_pointer(nfsi->delegation) != NULL) {
 		spin_lock(&clp->cl_lock);
 		delegation = nfs_detach_delegation_locked(nfsi, NULL, clp);
 		spin_unlock(&clp->cl_lock);
 		if (delegation != NULL) {
 			nfs_msync_inode(inode);
 			err = __nfs_inode_return_delegation(inode, delegation, 1);
 		}
 	}
 	return err;
 }

 static void nfs_mark_return_delegation(struct nfs_client *clp, struct nfs_delegation *delegation)
 {
 	set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 	set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
 }

 /*
  * Return all delegations associated to a super block
  */
 void nfs_super_return_all_delegations(struct super_block *sb)
 {
 	struct nfs_client *clp = NFS_SB(sb)->nfs_client;
 	struct nfs_delegation *delegation;

 	if (clp == NULL)
 		return;
 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
 		spin_lock(&delegation->lock);
 		if (delegation->inode != NULL && delegation->inode->i_sb == sb)
 			set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
 		spin_unlock(&delegation->lock);
 	}
 	rcu_read_unlock();
 	if (nfs_client_return_marked_delegations(clp) != 0)
 		nfs4_schedule_state_manager(clp);
 }

 static
 void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp, fmode_t flags)
 {
 	struct nfs_delegation *delegation;

 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
 		if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 			continue;
 		if (delegation->type & flags)
 			nfs_mark_return_delegation(clp, delegation);
 	}
 	rcu_read_unlock();
 }

 static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
 {
 	nfs_client_mark_return_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 }

 static void nfs_delegation_run_state_manager(struct nfs_client *clp)
 {
 	if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
 		nfs4_schedule_state_manager(clp);
 }

 void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
 {
 	nfs_client_mark_return_all_delegation_types(clp, flags);
 	nfs_delegation_run_state_manager(clp);
 }

 void nfs_expire_all_delegations(struct nfs_client *clp)
 {
 	nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 }

 /*
  * Return all delegations following an NFS4ERR_CB_PATH_DOWN error.
  */
 void nfs_handle_cb_pathdown(struct nfs_client *clp)
 {
 	if (clp == NULL)
 		return;
 	nfs_client_mark_return_all_delegations(clp);
 }

 static void nfs_client_mark_return_unreferenced_delegations(struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation;

 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
 		if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 			continue;
 		nfs_mark_return_delegation(clp, delegation);
 	}
 	rcu_read_unlock();
 }

 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 {
 	nfs_client_mark_return_unreferenced_delegations(clp);
 	nfs_delegation_run_state_manager(clp);
 }

 /*
  * Asynchronous delegation recall!
  */
 int nfs_async_inode_return_delegation(struct inode *inode, const nfs4_stateid *stateid,
 				      int (*validate_stateid)(struct nfs_delegation *delegation,
 							      const nfs4_stateid *stateid))
 {
 	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
 	struct nfs_delegation *delegation;

 	rcu_read_lock();
 	delegation = rcu_dereference(NFS_I(inode)->delegation);

 	if (!validate_stateid(delegation, stateid)) {
 		rcu_read_unlock();
 		return -ENOENT;
 	}

 	nfs_mark_return_delegation(clp, delegation);
 	rcu_read_unlock();
 	nfs_delegation_run_state_manager(clp);
 	return 0;
 }

 /*
  * Retrieve the inode associated with a delegation
  */
 struct inode *nfs_delegation_find_inode(struct nfs_client *clp, const struct nfs_fh *fhandle)
 {
 	struct nfs_delegation *delegation;
 	struct inode *res = NULL;
 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
 		spin_lock(&delegation->lock);
 		if (delegation->inode != NULL &&
 		    nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
 			res = igrab(delegation->inode);
 		}
 		spin_unlock(&delegation->lock);
 		if (res != NULL)
 			break;
 	}
 	rcu_read_unlock();
 	return res;
 }

 /*
  * Mark all delegations as needing to be reclaimed
  */
 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation;
 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list)
 		set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 	rcu_read_unlock();
 }

 /*
  * Reap all unclaimed delegations after reboot recovery is done
  */
 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation;
 	struct inode *inode;
 restart:
 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
 		if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags) == 0)
 			continue;
 		inode = nfs_delegation_grab_inode(delegation);
 		if (inode == NULL)
 			continue;
 		spin_lock(&clp->cl_lock);
 		delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL, clp);
 		spin_unlock(&clp->cl_lock);
 		rcu_read_unlock();
 		if (delegation != NULL)
 			nfs_free_delegation(delegation);
 		iput(inode);
 		goto restart;
 	}
 	rcu_read_unlock();
 }

 int nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode)
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_delegation *delegation;
 	int ret = 0;

 	rcu_read_lock();
 	delegation = rcu_dereference(nfsi->delegation);
 	if (delegation != NULL) {
 		memcpy(dst->data, delegation->stateid.data, sizeof(dst->data));
 		ret = 1;
 	}
 	rcu_read_unlock();
 	return ret;
 }
	/*
	* linux/fs/nfs/delegation.c
	*
	* Copyright (C) 2004 Trond Myklebust
	*
	* NFS file delegation management
	*
	*/
	#include <linux/completion.h>
	#include <linux/kthread.h>
	#include <linux/module.h>
	#include <linux/sched.h>
	#include <linux/slab.h>
	#include <linux/smp_lock.h>
	#include <linux/spinlock.h>

	#include <linux/nfs4.h>
	#include <linux/nfs_fs.h>
	#include <linux/nfs_xdr.h>

	#include "nfs4_fs.h"
	#include "delegation.h"
	#include "internal.h"

	static void nfs_do_free_delegation(struct nfs_delegation *delegation)
	{
	if (delegation->cred)
	put_rpccred(delegation->cred);
	kfree(delegation);
	}

	static void nfs_free_delegation_callback(struct rcu_head *head)
	{
	struct nfs_delegation *delegation = container_of(head, struct nfs_delegation, rcu);

	nfs_do_free_delegation(delegation);
	}

	static void nfs_free_delegation(struct nfs_delegation *delegation)
	{
	call_rcu(&delegation->rcu, nfs_free_delegation_callback);
	}

	void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
	{
	set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
	}

	int nfs_have_delegation(struct inode *inode, fmode_t flags)
	{
	struct nfs_delegation *delegation;
	int ret = 0;

	flags &= FMODE_READ\|FMODE_WRITE;
	rcu_read_lock();
	delegation = rcu_dereference(NFS_I(inode)->delegation);
	if (delegation != NULL && (delegation->type & flags) == flags) {
	nfs_mark_delegation_referenced(delegation);
	ret = 1;
	}
	rcu_read_unlock();
	return ret;
	}

	static int nfs_delegation_claim_locks(struct nfs_open_context ctx, struct nfs4_state state)
	{
	struct inode *inode = state->inode;
	struct file_lock *fl;
	int status = 0;

	if (inode->i_flock == NULL)
	goto out;

	/* Protect inode->i_flock using the BKL */
	lock_kernel();
	for (fl = inode->i_flock; fl != NULL; fl = fl->fl_next) {
	if (!(fl->fl_flags & (FL_POSIX\|FL_FLOCK)))
	continue;
	if (nfs_file_open_context(fl->fl_file) != ctx)
	continue;
	unlock_kernel();
	status = nfs4_lock_delegation_recall(state, fl);
	if (status < 0)
	goto out;
	lock_kernel();
	}
	unlock_kernel();
	out:
	return status;
	}

	static int nfs_delegation_claim_opens(struct inode inode, const nfs4_stateid stateid)
	{
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_open_context *ctx;
	struct nfs4_state *state;
	int err;

	again:
	spin_lock(&inode->i_lock);
	list_for_each_entry(ctx, &nfsi->open_files, list) {
	state = ctx->state;
	if (state == NULL)
	continue;
	if (!test_bit(NFS_DELEGATED_STATE, &state->flags))
	continue;
	if (memcmp(state->stateid.data, stateid->data, sizeof(state->stateid.data)) != 0)
	continue;
	get_nfs_open_context(ctx);
	spin_unlock(&inode->i_lock);
	err = nfs4_open_delegation_recall(ctx, state, stateid);
	if (err >= 0)
	err = nfs_delegation_claim_locks(ctx, state);
	put_nfs_open_context(ctx);
	if (err != 0)
	return err;
	goto again;
	}
	spin_unlock(&inode->i_lock);
	return 0;
	}

	/*
	* Set up a delegation on an inode
	*/
	void nfs_inode_reclaim_delegation(struct inode inode, struct rpc_cred cred, struct nfs_openres *res)
	{
	struct nfs_delegation *delegation;
	struct rpc_cred *oldcred = NULL;

	rcu_read_lock();
	delegation = rcu_dereference(NFS_I(inode)->delegation);
	if (delegation != NULL) {
	spin_lock(&delegation->lock);
	if (delegation->inode != NULL) {
	memcpy(delegation->stateid.data, res->delegation.data,
	sizeof(delegation->stateid.data));
	delegation->type = res->delegation_type;
	delegation->maxsize = res->maxsize;
	oldcred = delegation->cred;
	delegation->cred = get_rpccred(cred);
	clear_bit(NFS_DELEGATION_NEED_RECLAIM,
	&delegation->flags);
	NFS_I(inode)->delegation_state = delegation->type;
	spin_unlock(&delegation->lock);
	put_rpccred(oldcred);
	rcu_read_unlock();
	} else {
	/* We appear to have raced with a delegation return. */
	spin_unlock(&delegation->lock);
	rcu_read_unlock();
	nfs_inode_set_delegation(inode, cred, res);
	}
	} else {
	rcu_read_unlock();
	}
	}

	static int nfs_do_return_delegation(struct inode inode, struct nfs_delegation delegation, int issync)
	{
	int res = 0;

	res = nfs4_proc_delegreturn(inode, delegation->cred, &delegation->stateid, issync);
	nfs_free_delegation(delegation);
	return res;
	}

	static struct inode nfs_delegation_grab_inode(struct nfs_delegation delegation)
	{
	struct inode *inode = NULL;

	spin_lock(&delegation->lock);
	if (delegation->inode != NULL)
	inode = igrab(delegation->inode);
	spin_unlock(&delegation->lock);
	return inode;
	}

	static struct nfs_delegation nfs_detach_delegation_locked(struct nfs_inode nfsi,
	const nfs4_stateid *stateid,
	struct nfs_client *clp)
	{
	struct nfs_delegation *delegation =
	rcu_dereference_protected(nfsi->delegation,
	lockdep_is_held(&clp->cl_lock));

	if (delegation == NULL)
	goto nomatch;
	spin_lock(&delegation->lock);
	if (stateid != NULL && memcmp(delegation->stateid.data, stateid->data,
	sizeof(delegation->stateid.data)) != 0)
	goto nomatch_unlock;
	list_del_rcu(&delegation->super_list);
	delegation->inode = NULL;
	nfsi->delegation_state = 0;
	rcu_assign_pointer(nfsi->delegation, NULL);
	spin_unlock(&delegation->lock);
	return delegation;
	nomatch_unlock:
	spin_unlock(&delegation->lock);
	nomatch:
	return NULL;
	}

	/*
	* Set up a delegation on an inode
	*/
	int nfs_inode_set_delegation(struct inode inode, struct rpc_cred cred, struct nfs_openres *res)
	{
	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation delegation, old_delegation;
	struct nfs_delegation *freeme = NULL;
	int status = 0;

	delegation = kmalloc(sizeof(*delegation), GFP_NOFS);
	if (delegation == NULL)
	return -ENOMEM;
	memcpy(delegation->stateid.data, res->delegation.data,
	sizeof(delegation->stateid.data));
	delegation->type = res->delegation_type;
	delegation->maxsize = res->maxsize;
	delegation->change_attr = nfsi->change_attr;
	delegation->cred = get_rpccred(cred);
	delegation->inode = inode;
	delegation->flags = 1<<NFS_DELEGATION_REFERENCED;
	spin_lock_init(&delegation->lock);

	spin_lock(&clp->cl_lock);
	old_delegation = rcu_dereference_protected(nfsi->delegation,
	lockdep_is_held(&clp->cl_lock));
	if (old_delegation != NULL) {
	if (memcmp(&delegation->stateid, &old_delegation->stateid,
	sizeof(old_delegation->stateid)) == 0 &&
	delegation->type == old_delegation->type) {
	goto out;
	}
	/*
	* Deal with broken servers that hand out two
	* delegations for the same file.
	*/
	dfprintk(FILE, "%s: server %s handed out "
	"a duplicate delegation!\n",
	__func__, clp->cl_hostname);
	if (delegation->type <= old_delegation->type) {
	freeme = delegation;
	delegation = NULL;
	goto out;
	}
	freeme = nfs_detach_delegation_locked(nfsi, NULL, clp);
	}
	list_add_rcu(&delegation->super_list, &clp->cl_delegations);
	nfsi->delegation_state = delegation->type;
	rcu_assign_pointer(nfsi->delegation, delegation);
	delegation = NULL;

	/* Ensure we revalidate the attributes and page cache! */
	spin_lock(&inode->i_lock);
	nfsi->cache_validity \|= NFS_INO_REVAL_FORCED;
	spin_unlock(&inode->i_lock);

	out:
	spin_unlock(&clp->cl_lock);
	if (delegation != NULL)
	nfs_free_delegation(delegation);
	if (freeme != NULL)
	nfs_do_return_delegation(inode, freeme, 0);
	return status;
	}

	/* Sync all data to disk upon delegation return */
	static void nfs_msync_inode(struct inode *inode)
	{
	filemap_fdatawrite(inode->i_mapping);
	nfs_wb_all(inode);
	filemap_fdatawait(inode->i_mapping);
	}

	/*
	* Basic procedure for returning a delegation to the server
	*/
	static int __nfs_inode_return_delegation(struct inode inode, struct nfs_delegation delegation, int issync)
	{
	struct nfs_inode *nfsi = NFS_I(inode);
	int err;

	/*
	* Guard against new delegated open/lock/unlock calls and against
	* state recovery
	*/
	down_write(&nfsi->rwsem);
	err = nfs_delegation_claim_opens(inode, &delegation->stateid);
	up_write(&nfsi->rwsem);
	if (err)
	goto out;

	err = nfs_do_return_delegation(inode, delegation, issync);
	out:
	return err;
	}

	/*
	* Return all delegations that have been marked for return
	*/
	int nfs_client_return_marked_delegations(struct nfs_client *clp)
	{
	struct nfs_delegation *delegation;
	struct inode *inode;
	int err = 0;

	restart:
	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
	if (!test_and_clear_bit(NFS_DELEGATION_RETURN, &delegation->flags))
	continue;
	inode = nfs_delegation_grab_inode(delegation);
	if (inode == NULL)
	continue;
	spin_lock(&clp->cl_lock);
	delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL, clp);
	spin_unlock(&clp->cl_lock);
	rcu_read_unlock();
	if (delegation != NULL) {
	filemap_flush(inode->i_mapping);
	err = __nfs_inode_return_delegation(inode, delegation, 0);
	}
	iput(inode);
	if (!err)
	goto restart;
	set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
	return err;
	}
	rcu_read_unlock();
	return 0;
	}

	/*
	* This function returns the delegation without reclaiming opens
	* or protecting against delegation reclaims.
	* It is therefore really only safe to be called from
	* nfs4_clear_inode()
	*/
	void nfs_inode_return_delegation_noreclaim(struct inode *inode)
	{
	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;

	if (rcu_access_pointer(nfsi->delegation) != NULL) {
	spin_lock(&clp->cl_lock);
	delegation = nfs_detach_delegation_locked(nfsi, NULL, clp);
	spin_unlock(&clp->cl_lock);
	if (delegation != NULL)
	nfs_do_return_delegation(inode, delegation, 0);
	}
	}

	int nfs_inode_return_delegation(struct inode *inode)
	{
	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;
	int err = 0;

	if (rcu_access_pointer(nfsi->delegation) != NULL) {
	spin_lock(&clp->cl_lock);
	delegation = nfs_detach_delegation_locked(nfsi, NULL, clp);
	spin_unlock(&clp->cl_lock);
	if (delegation != NULL) {
	nfs_msync_inode(inode);
	err = __nfs_inode_return_delegation(inode, delegation, 1);
	}
	}
	return err;
	}

	static void nfs_mark_return_delegation(struct nfs_client clp, struct nfs_delegation delegation)
	{
	set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
	set_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state);
	}

	/*
	* Return all delegations associated to a super block
	*/
	void nfs_super_return_all_delegations(struct super_block *sb)
	{
	struct nfs_client *clp = NFS_SB(sb)->nfs_client;
	struct nfs_delegation *delegation;

	if (clp == NULL)
	return;
	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
	spin_lock(&delegation->lock);
	if (delegation->inode != NULL && delegation->inode->i_sb == sb)
	set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
	spin_unlock(&delegation->lock);
	}
	rcu_read_unlock();
	if (nfs_client_return_marked_delegations(clp) != 0)
	nfs4_schedule_state_manager(clp);
	}

	static
	void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp, fmode_t flags)
	{
	struct nfs_delegation *delegation;

	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
	if ((delegation->type == (FMODE_READ\|FMODE_WRITE)) && !(flags & FMODE_WRITE))
	continue;
	if (delegation->type & flags)
	nfs_mark_return_delegation(clp, delegation);
	}
	rcu_read_unlock();
	}

	static void nfs_client_mark_return_all_delegations(struct nfs_client *clp)
	{
	nfs_client_mark_return_all_delegation_types(clp, FMODE_READ\|FMODE_WRITE);
	}

	static void nfs_delegation_run_state_manager(struct nfs_client *clp)
	{
	if (test_bit(NFS4CLNT_DELEGRETURN, &clp->cl_state))
	nfs4_schedule_state_manager(clp);
	}

	void nfs_expire_all_delegation_types(struct nfs_client *clp, fmode_t flags)
	{
	nfs_client_mark_return_all_delegation_types(clp, flags);
	nfs_delegation_run_state_manager(clp);
	}

	void nfs_expire_all_delegations(struct nfs_client *clp)
	{
	nfs_expire_all_delegation_types(clp, FMODE_READ\|FMODE_WRITE);
	}

	/*
	* Return all delegations following an NFS4ERR_CB_PATH_DOWN error.
	*/
	void nfs_handle_cb_pathdown(struct nfs_client *clp)
	{
	if (clp == NULL)
	return;
	nfs_client_mark_return_all_delegations(clp);
	}

	static void nfs_client_mark_return_unreferenced_delegations(struct nfs_client *clp)
	{
	struct nfs_delegation *delegation;

	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
	if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
	continue;
	nfs_mark_return_delegation(clp, delegation);
	}
	rcu_read_unlock();
	}

	void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
	{
	nfs_client_mark_return_unreferenced_delegations(clp);
	nfs_delegation_run_state_manager(clp);
	}

	/*
	* Asynchronous delegation recall!
	*/
	int nfs_async_inode_return_delegation(struct inode inode, const nfs4_stateid stateid,
	int (validate_stateid)(struct nfs_delegation delegation,
	const nfs4_stateid *stateid))
	{
	struct nfs_client *clp = NFS_SERVER(inode)->nfs_client;
	struct nfs_delegation *delegation;

	rcu_read_lock();
	delegation = rcu_dereference(NFS_I(inode)->delegation);

	if (!validate_stateid(delegation, stateid)) {
	rcu_read_unlock();
	return -ENOENT;
	}

	nfs_mark_return_delegation(clp, delegation);
	rcu_read_unlock();
	nfs_delegation_run_state_manager(clp);
	return 0;
	}

	/*
	* Retrieve the inode associated with a delegation
	*/
	struct inode nfs_delegation_find_inode(struct nfs_client clp, const struct nfs_fh *fhandle)
	{
	struct nfs_delegation *delegation;
	struct inode *res = NULL;
	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
	spin_lock(&delegation->lock);
	if (delegation->inode != NULL &&
	nfs_compare_fh(fhandle, &NFS_I(delegation->inode)->fh) == 0) {
	res = igrab(delegation->inode);
	}
	spin_unlock(&delegation->lock);
	if (res != NULL)
	break;
	}
	rcu_read_unlock();
	return res;
	}

	/*
	* Mark all delegations as needing to be reclaimed
	*/
	void nfs_delegation_mark_reclaim(struct nfs_client *clp)
	{
	struct nfs_delegation *delegation;
	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list)
	set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
	rcu_read_unlock();
	}

	/*
	* Reap all unclaimed delegations after reboot recovery is done
	*/
	void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
	{
	struct nfs_delegation *delegation;
	struct inode *inode;
	restart:
	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &clp->cl_delegations, super_list) {
	if (test_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags) == 0)
	continue;
	inode = nfs_delegation_grab_inode(delegation);
	if (inode == NULL)
	continue;
	spin_lock(&clp->cl_lock);
	delegation = nfs_detach_delegation_locked(NFS_I(inode), NULL, clp);
	spin_unlock(&clp->cl_lock);
	rcu_read_unlock();
	if (delegation != NULL)
	nfs_free_delegation(delegation);
	iput(inode);
	goto restart;
	}
	rcu_read_unlock();
	}

	int nfs4_copy_delegation_stateid(nfs4_stateid dst, struct inode inode)
	{
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;
	int ret = 0;

	rcu_read_lock();
	delegation = rcu_dereference(nfsi->delegation);
	if (delegation != NULL) {
	memcpy(dst->data, delegation->stateid.data, sizeof(dst->data));
	ret = 1;
	}
	rcu_read_unlock();
	return ret;
	}