fs/nfs/delegation.c - kernel/msm-4.19 - Gitiles

 /*
  * 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/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_free_delegation(struct nfs_delegation *delegation)
 {
 	if (delegation->cred) {
 		put_rpccred(delegation->cred);
 		delegation->cred = NULL;
 	}
 	kfree_rcu(delegation, rcu);
 }

 /**
  * nfs_mark_delegation_referenced - set delegation's REFERENCED flag
  * @delegation: delegation to process
  *
  */
 void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
 {
 	set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
 }

 /**
  * nfs_have_delegation - check if inode has a delegation
  * @inode: inode to check
  * @flags: delegation types to check for
  *
  * Returns one if inode has the indicated delegation, otherwise zero.
  */
 int nfs4_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 file locks lock */
 	lock_flocks();
 	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_flocks();
 		status = nfs4_lock_delegation_recall(state, fl);
 		if (status < 0)
 			goto out;
 		lock_flocks();
 	}
 	unlock_flocks();
 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 (!nfs4_stateid_match(&state->stateid, stateid))
 			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;
 }

 /**
  * nfs_inode_reclaim_delegation - process a delegation reclaim request
  * @inode: inode to process
  * @cred: credential to use for request
  * @res: new delegation state from server
  *
  */
 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) {
 			nfs4_stateid_copy(&delegation->stateid, &res->delegation);
 			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,
 			     struct nfs_server *server)
 {
 	struct nfs_delegation *delegation =
 		rcu_dereference_protected(nfsi->delegation,
 				lockdep_is_held(&server->nfs_client->cl_lock));

 	if (delegation == NULL)
 		goto nomatch;

 	spin_lock(&delegation->lock);
 	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:
 	return NULL;
 }

 static struct nfs_delegation *nfs_detach_delegation(struct nfs_inode *nfsi,
 						    struct nfs_server *server)
 {
 	struct nfs_client *clp = server->nfs_client;
 	struct nfs_delegation *delegation;

 	spin_lock(&clp->cl_lock);
 	delegation = nfs_detach_delegation_locked(nfsi, server);
 	spin_unlock(&clp->cl_lock);
 	return delegation;
 }

 /**
  * nfs_inode_set_delegation - set up a delegation on an inode
  * @inode: inode to which delegation applies
  * @cred: cred to use for subsequent delegation processing
  * @res: new delegation state from server
  *
  * Returns zero on success, or a negative errno value.
  */
 int nfs_inode_set_delegation(struct inode *inode, struct rpc_cred *cred, struct nfs_openres *res)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_client *clp = server->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;
 	nfs4_stateid_copy(&delegation->stateid, &res->delegation);
 	delegation->type = res->delegation_type;
 	delegation->maxsize = res->maxsize;
 	delegation->change_attr = inode->i_version;
 	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 (nfs4_stateid_match(&delegation->stateid,
 					&old_delegation->stateid) &&
 				delegation->type == old_delegation->type) {
 			goto out;
 		}
 		/*
 		 * Deal with broken servers that hand out two
 		 * delegations for the same file.
 		 * Allow for upgrades to a WRITE delegation, but
 		 * nothing else.
 		 */
 		dfprintk(FILE, "%s: server %s handed out "
 				"a duplicate delegation!\n",
 				__func__, clp->cl_hostname);
 		if (delegation->type == old_delegation->type ||
 		    !(delegation->type & FMODE_WRITE)) {
 			freeme = delegation;
 			delegation = NULL;
 			goto out;
 		}
 		freeme = nfs_detach_delegation_locked(nfsi, server);
 	}
 	list_add_rcu(&delegation->super_list, &server->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;
 }

 /*
  * 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;
 }

 /**
  * nfs_client_return_marked_delegations - return previously marked delegations
  * @clp: nfs_client to process
  *
  * Note that this function is designed to be called by the state
  * manager thread. For this reason, it cannot flush the dirty data,
  * since that could deadlock in case of a state recovery error.
  *
  * Returns zero on success, or a negative errno value.
  */
 int nfs_client_return_marked_delegations(struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation;
 	struct nfs_server *server;
 	struct inode *inode;
 	int err = 0;

 restart:
 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 		list_for_each_entry_rcu(delegation, &server->delegations,
 								super_list) {
 			if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
 							&delegation->flags))
 				continue;
 			inode = nfs_delegation_grab_inode(delegation);
 			if (inode == NULL)
 				continue;
 			delegation = nfs_detach_delegation(NFS_I(inode),
 								server);
 			rcu_read_unlock();

 			if (delegation != NULL)
 				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;
 }

 /**
  * nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
  * @inode: inode to process
  *
  * Does not protect against delegation reclaims, therefore really only safe
  * to be called from nfs4_clear_inode().
  */
 void nfs_inode_return_delegation_noreclaim(struct inode *inode)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_delegation *delegation;

 	if (rcu_access_pointer(nfsi->delegation) != NULL) {
 		delegation = nfs_detach_delegation(nfsi, server);
 		if (delegation != NULL)
 			nfs_do_return_delegation(inode, delegation, 0);
 	}
 }

 /**
  * nfs_inode_return_delegation - synchronously return a delegation
  * @inode: inode to process
  *
  * This routine will always flush any dirty data to disk on the
  * assumption that if we need to return the delegation, then
  * we should stop caching.
  *
  * Returns zero on success, or a negative errno value.
  */
 int nfs_inode_return_delegation(struct inode *inode)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_delegation *delegation;
 	int err = 0;

 	nfs_wb_all(inode);
 	if (rcu_access_pointer(nfsi->delegation) != NULL) {
 		delegation = nfs_detach_delegation(nfsi, server);
 		if (delegation != NULL) {
 			err = __nfs_inode_return_delegation(inode, delegation, 1);
 		}
 	}
 	return err;
 }

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

 /**
  * nfs_super_return_all_delegations - return delegations for one superblock
  * @sb: sb to process
  *
  */
 void nfs_server_return_all_delegations(struct nfs_server *server)
 {
 	struct nfs_client *clp = server->nfs_client;
 	struct nfs_delegation *delegation;

 	if (clp == NULL)
 		return;

 	rcu_read_lock();
 	list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 		spin_lock(&delegation->lock);
 		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_mark_return_all_delegation_types(struct nfs_server *server,
 						 fmode_t flags)
 {
 	struct nfs_delegation *delegation;

 	list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 		if ((delegation->type == (FMODE_READ|FMODE_WRITE)) && !(flags & FMODE_WRITE))
 			continue;
 		if (delegation->type & flags)
 			nfs_mark_return_delegation(server, delegation);
 	}
 }

 static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
 							fmode_t flags)
 {
 	struct nfs_server *server;

 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 		nfs_mark_return_all_delegation_types(server, flags);
 	rcu_read_unlock();
 }

 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_remove_bad_delegation(struct inode *inode)
 {
 	struct nfs_delegation *delegation;

 	delegation = nfs_detach_delegation(NFS_I(inode), NFS_SERVER(inode));
 	if (delegation) {
 		nfs_inode_find_state_and_recover(inode, &delegation->stateid);
 		nfs_free_delegation(delegation);
 	}
 }
 EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);

 /**
  * nfs_expire_all_delegation_types
  * @clp: client to process
  * @flags: delegation types to expire
  *
  */
 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);
 }

 /**
  * nfs_expire_all_delegations
  * @clp: client to process
  *
  */
 void nfs_expire_all_delegations(struct nfs_client *clp)
 {
 	nfs_expire_all_delegation_types(clp, FMODE_READ|FMODE_WRITE);
 }

 static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
 {
 	struct nfs_delegation *delegation;

 	list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
 		if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
 			continue;
 		nfs_mark_return_delegation(server, delegation);
 	}
 }

 /**
  * nfs_expire_unreferenced_delegations - Eliminate unused delegations
  * @clp: nfs_client to process
  *
  */
 void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
 {
 	struct nfs_server *server;

 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 		nfs_mark_return_unreferenced_delegations(server);
 	rcu_read_unlock();

 	nfs_delegation_run_state_manager(clp);
 }

 /**
  * nfs_async_inode_return_delegation - asynchronously return a delegation
  * @inode: inode to process
  * @stateid: state ID information
  *
  * Returns zero on success, or a negative errno value.
  */
 int nfs_async_inode_return_delegation(struct inode *inode,
 				      const nfs4_stateid *stateid)
 {
 	struct nfs_server *server = NFS_SERVER(inode);
 	struct nfs_client *clp = server->nfs_client;
 	struct nfs_delegation *delegation;

 	filemap_flush(inode->i_mapping);

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

 	if (!clp->cl_mvops->match_stateid(&delegation->stateid, stateid)) {
 		rcu_read_unlock();
 		return -ENOENT;
 	}
 	nfs_mark_return_delegation(server, delegation);
 	rcu_read_unlock();

 	nfs_delegation_run_state_manager(clp);
 	return 0;
 }

 static struct inode *
 nfs_delegation_find_inode_server(struct nfs_server *server,
 				 const struct nfs_fh *fhandle)
 {
 	struct nfs_delegation *delegation;
 	struct inode *res = NULL;

 	list_for_each_entry_rcu(delegation, &server->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;
 	}
 	return res;
 }

 /**
  * nfs_delegation_find_inode - retrieve the inode associated with a delegation
  * @clp: client state handle
  * @fhandle: filehandle from a delegation recall
  *
  * Returns pointer to inode matching "fhandle," or NULL if a matching inode
  * cannot be found.
  */
 struct inode *nfs_delegation_find_inode(struct nfs_client *clp,
 					const struct nfs_fh *fhandle)
 {
 	struct nfs_server *server;
 	struct inode *res = NULL;

 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 		res = nfs_delegation_find_inode_server(server, fhandle);
 		if (res != NULL)
 			break;
 	}
 	rcu_read_unlock();
 	return res;
 }

 static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
 {
 	struct nfs_delegation *delegation;

 	list_for_each_entry_rcu(delegation, &server->delegations, super_list)
 		set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
 }

 /**
  * nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
  * @clp: nfs_client to process
  *
  */
 void nfs_delegation_mark_reclaim(struct nfs_client *clp)
 {
 	struct nfs_server *server;

 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 		nfs_delegation_mark_reclaim_server(server);
 	rcu_read_unlock();
 }

 /**
  * nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
  * @clp: nfs_client to process
  *
  */
 void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
 {
 	struct nfs_delegation *delegation;
 	struct nfs_server *server;
 	struct inode *inode;

 restart:
 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
 		list_for_each_entry_rcu(delegation, &server->delegations,
 								super_list) {
 			if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
 						&delegation->flags) == 0)
 				continue;
 			inode = nfs_delegation_grab_inode(delegation);
 			if (inode == NULL)
 				continue;
 			delegation = nfs_detach_delegation(NFS_I(inode),
 								server);
 			rcu_read_unlock();

 			if (delegation != NULL)
 				nfs_free_delegation(delegation);
 			iput(inode);
 			goto restart;
 		}
 	}
 	rcu_read_unlock();
 }

 /**
  * nfs_delegations_present - check for existence of delegations
  * @clp: client state handle
  *
  * Returns one if there are any nfs_delegation structures attached
  * to this nfs_client.
  */
 int nfs_delegations_present(struct nfs_client *clp)
 {
 	struct nfs_server *server;
 	int ret = 0;

 	rcu_read_lock();
 	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
 		if (!list_empty(&server->delegations)) {
 			ret = 1;
 			break;
 		}
 	rcu_read_unlock();
 	return ret;
 }

 /**
  * nfs4_copy_delegation_stateid - Copy inode's state ID information
  * @dst: stateid data structure to fill in
  * @inode: inode to check
  * @flags: delegation type requirement
  *
  * Returns "true" and fills in "dst->data" * if inode had a delegation,
  * otherwise "false" is returned.
  */
 bool nfs4_copy_delegation_stateid(nfs4_stateid *dst, struct inode *inode,
 		fmode_t flags)
 {
 	struct nfs_inode *nfsi = NFS_I(inode);
 	struct nfs_delegation *delegation;
 	bool ret;

 	flags &= FMODE_READ|FMODE_WRITE;
 	rcu_read_lock();
 	delegation = rcu_dereference(nfsi->delegation);
 	ret = (delegation != NULL && (delegation->type & flags) == flags);
 	if (ret) {
 		nfs4_stateid_copy(dst, &delegation->stateid);
 		nfs_mark_delegation_referenced(delegation);
 	}
 	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/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_free_delegation(struct nfs_delegation *delegation)
	{
	if (delegation->cred) {
	put_rpccred(delegation->cred);
	delegation->cred = NULL;
	}
	kfree_rcu(delegation, rcu);
	}

	/**
	* nfs_mark_delegation_referenced - set delegation's REFERENCED flag
	* @delegation: delegation to process
	*
	*/
	void nfs_mark_delegation_referenced(struct nfs_delegation *delegation)
	{
	set_bit(NFS_DELEGATION_REFERENCED, &delegation->flags);
	}

	/**
	* nfs_have_delegation - check if inode has a delegation
	* @inode: inode to check
	* @flags: delegation types to check for
	*
	* Returns one if inode has the indicated delegation, otherwise zero.
	*/
	int nfs4_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 file locks lock */
	lock_flocks();
	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_flocks();
	status = nfs4_lock_delegation_recall(state, fl);
	if (status < 0)
	goto out;
	lock_flocks();
	}
	unlock_flocks();
	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 (!nfs4_stateid_match(&state->stateid, stateid))
	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;
	}

	/**
	* nfs_inode_reclaim_delegation - process a delegation reclaim request
	* @inode: inode to process
	* @cred: credential to use for request
	* @res: new delegation state from server
	*
	*/
	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) {
	nfs4_stateid_copy(&delegation->stateid, &res->delegation);
	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,
	struct nfs_server *server)
	{
	struct nfs_delegation *delegation =
	rcu_dereference_protected(nfsi->delegation,
	lockdep_is_held(&server->nfs_client->cl_lock));

	if (delegation == NULL)
	goto nomatch;

	spin_lock(&delegation->lock);
	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:
	return NULL;
	}

	static struct nfs_delegation nfs_detach_delegation(struct nfs_inode nfsi,
	struct nfs_server *server)
	{
	struct nfs_client *clp = server->nfs_client;
	struct nfs_delegation *delegation;

	spin_lock(&clp->cl_lock);
	delegation = nfs_detach_delegation_locked(nfsi, server);
	spin_unlock(&clp->cl_lock);
	return delegation;
	}

	/**
	* nfs_inode_set_delegation - set up a delegation on an inode
	* @inode: inode to which delegation applies
	* @cred: cred to use for subsequent delegation processing
	* @res: new delegation state from server
	*
	* Returns zero on success, or a negative errno value.
	*/
	int nfs_inode_set_delegation(struct inode inode, struct rpc_cred cred, struct nfs_openres *res)
	{
	struct nfs_server *server = NFS_SERVER(inode);
	struct nfs_client *clp = server->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;
	nfs4_stateid_copy(&delegation->stateid, &res->delegation);
	delegation->type = res->delegation_type;
	delegation->maxsize = res->maxsize;
	delegation->change_attr = inode->i_version;
	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 (nfs4_stateid_match(&delegation->stateid,
	&old_delegation->stateid) &&
	delegation->type == old_delegation->type) {
	goto out;
	}
	/*
	* Deal with broken servers that hand out two
	* delegations for the same file.
	* Allow for upgrades to a WRITE delegation, but
	* nothing else.
	*/
	dfprintk(FILE, "%s: server %s handed out "
	"a duplicate delegation!\n",
	__func__, clp->cl_hostname);
	if (delegation->type == old_delegation->type \|\|
	!(delegation->type & FMODE_WRITE)) {
	freeme = delegation;
	delegation = NULL;
	goto out;
	}
	freeme = nfs_detach_delegation_locked(nfsi, server);
	}
	list_add_rcu(&delegation->super_list, &server->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;
	}

	/*
	* 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;
	}

	/**
	* nfs_client_return_marked_delegations - return previously marked delegations
	* @clp: nfs_client to process
	*
	* Note that this function is designed to be called by the state
	* manager thread. For this reason, it cannot flush the dirty data,
	* since that could deadlock in case of a state recovery error.
	*
	* Returns zero on success, or a negative errno value.
	*/
	int nfs_client_return_marked_delegations(struct nfs_client *clp)
	{
	struct nfs_delegation *delegation;
	struct nfs_server *server;
	struct inode *inode;
	int err = 0;

	restart:
	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
	list_for_each_entry_rcu(delegation, &server->delegations,
	super_list) {
	if (!test_and_clear_bit(NFS_DELEGATION_RETURN,
	&delegation->flags))
	continue;
	inode = nfs_delegation_grab_inode(delegation);
	if (inode == NULL)
	continue;
	delegation = nfs_detach_delegation(NFS_I(inode),
	server);
	rcu_read_unlock();

	if (delegation != NULL)
	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;
	}

	/**
	* nfs_inode_return_delegation_noreclaim - return delegation, don't reclaim opens
	* @inode: inode to process
	*
	* Does not protect against delegation reclaims, therefore really only safe
	* to be called from nfs4_clear_inode().
	*/
	void nfs_inode_return_delegation_noreclaim(struct inode *inode)
	{
	struct nfs_server *server = NFS_SERVER(inode);
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;

	if (rcu_access_pointer(nfsi->delegation) != NULL) {
	delegation = nfs_detach_delegation(nfsi, server);
	if (delegation != NULL)
	nfs_do_return_delegation(inode, delegation, 0);
	}
	}

	/**
	* nfs_inode_return_delegation - synchronously return a delegation
	* @inode: inode to process
	*
	* This routine will always flush any dirty data to disk on the
	* assumption that if we need to return the delegation, then
	* we should stop caching.
	*
	* Returns zero on success, or a negative errno value.
	*/
	int nfs_inode_return_delegation(struct inode *inode)
	{
	struct nfs_server *server = NFS_SERVER(inode);
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;
	int err = 0;

	nfs_wb_all(inode);
	if (rcu_access_pointer(nfsi->delegation) != NULL) {
	delegation = nfs_detach_delegation(nfsi, server);
	if (delegation != NULL) {
	err = __nfs_inode_return_delegation(inode, delegation, 1);
	}
	}
	return err;
	}

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

	/**
	* nfs_super_return_all_delegations - return delegations for one superblock
	* @sb: sb to process
	*
	*/
	void nfs_server_return_all_delegations(struct nfs_server *server)
	{
	struct nfs_client *clp = server->nfs_client;
	struct nfs_delegation *delegation;

	if (clp == NULL)
	return;

	rcu_read_lock();
	list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
	spin_lock(&delegation->lock);
	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_mark_return_all_delegation_types(struct nfs_server *server,
	fmode_t flags)
	{
	struct nfs_delegation *delegation;

	list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
	if ((delegation->type == (FMODE_READ\|FMODE_WRITE)) && !(flags & FMODE_WRITE))
	continue;
	if (delegation->type & flags)
	nfs_mark_return_delegation(server, delegation);
	}
	}

	static void nfs_client_mark_return_all_delegation_types(struct nfs_client *clp,
	fmode_t flags)
	{
	struct nfs_server *server;

	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
	nfs_mark_return_all_delegation_types(server, flags);
	rcu_read_unlock();
	}

	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_remove_bad_delegation(struct inode *inode)
	{
	struct nfs_delegation *delegation;

	delegation = nfs_detach_delegation(NFS_I(inode), NFS_SERVER(inode));
	if (delegation) {
	nfs_inode_find_state_and_recover(inode, &delegation->stateid);
	nfs_free_delegation(delegation);
	}
	}
	EXPORT_SYMBOL_GPL(nfs_remove_bad_delegation);

	/**
	* nfs_expire_all_delegation_types
	* @clp: client to process
	* @flags: delegation types to expire
	*
	*/
	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);
	}

	/**
	* nfs_expire_all_delegations
	* @clp: client to process
	*
	*/
	void nfs_expire_all_delegations(struct nfs_client *clp)
	{
	nfs_expire_all_delegation_types(clp, FMODE_READ\|FMODE_WRITE);
	}

	static void nfs_mark_return_unreferenced_delegations(struct nfs_server *server)
	{
	struct nfs_delegation *delegation;

	list_for_each_entry_rcu(delegation, &server->delegations, super_list) {
	if (test_and_clear_bit(NFS_DELEGATION_REFERENCED, &delegation->flags))
	continue;
	nfs_mark_return_delegation(server, delegation);
	}
	}

	/**
	* nfs_expire_unreferenced_delegations - Eliminate unused delegations
	* @clp: nfs_client to process
	*
	*/
	void nfs_expire_unreferenced_delegations(struct nfs_client *clp)
	{
	struct nfs_server *server;

	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
	nfs_mark_return_unreferenced_delegations(server);
	rcu_read_unlock();

	nfs_delegation_run_state_manager(clp);
	}

	/**
	* nfs_async_inode_return_delegation - asynchronously return a delegation
	* @inode: inode to process
	* @stateid: state ID information
	*
	* Returns zero on success, or a negative errno value.
	*/
	int nfs_async_inode_return_delegation(struct inode *inode,
	const nfs4_stateid *stateid)
	{
	struct nfs_server *server = NFS_SERVER(inode);
	struct nfs_client *clp = server->nfs_client;
	struct nfs_delegation *delegation;

	filemap_flush(inode->i_mapping);

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

	if (!clp->cl_mvops->match_stateid(&delegation->stateid, stateid)) {
	rcu_read_unlock();
	return -ENOENT;
	}
	nfs_mark_return_delegation(server, delegation);
	rcu_read_unlock();

	nfs_delegation_run_state_manager(clp);
	return 0;
	}

	static struct inode *
	nfs_delegation_find_inode_server(struct nfs_server *server,
	const struct nfs_fh *fhandle)
	{
	struct nfs_delegation *delegation;
	struct inode *res = NULL;

	list_for_each_entry_rcu(delegation, &server->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;
	}
	return res;
	}

	/**
	* nfs_delegation_find_inode - retrieve the inode associated with a delegation
	* @clp: client state handle
	* @fhandle: filehandle from a delegation recall
	*
	* Returns pointer to inode matching "fhandle," or NULL if a matching inode
	* cannot be found.
	*/
	struct inode nfs_delegation_find_inode(struct nfs_client clp,
	const struct nfs_fh *fhandle)
	{
	struct nfs_server *server;
	struct inode *res = NULL;

	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
	res = nfs_delegation_find_inode_server(server, fhandle);
	if (res != NULL)
	break;
	}
	rcu_read_unlock();
	return res;
	}

	static void nfs_delegation_mark_reclaim_server(struct nfs_server *server)
	{
	struct nfs_delegation *delegation;

	list_for_each_entry_rcu(delegation, &server->delegations, super_list)
	set_bit(NFS_DELEGATION_NEED_RECLAIM, &delegation->flags);
	}

	/**
	* nfs_delegation_mark_reclaim - mark all delegations as needing to be reclaimed
	* @clp: nfs_client to process
	*
	*/
	void nfs_delegation_mark_reclaim(struct nfs_client *clp)
	{
	struct nfs_server *server;

	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
	nfs_delegation_mark_reclaim_server(server);
	rcu_read_unlock();
	}

	/**
	* nfs_delegation_reap_unclaimed - reap unclaimed delegations after reboot recovery is done
	* @clp: nfs_client to process
	*
	*/
	void nfs_delegation_reap_unclaimed(struct nfs_client *clp)
	{
	struct nfs_delegation *delegation;
	struct nfs_server *server;
	struct inode *inode;

	restart:
	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link) {
	list_for_each_entry_rcu(delegation, &server->delegations,
	super_list) {
	if (test_bit(NFS_DELEGATION_NEED_RECLAIM,
	&delegation->flags) == 0)
	continue;
	inode = nfs_delegation_grab_inode(delegation);
	if (inode == NULL)
	continue;
	delegation = nfs_detach_delegation(NFS_I(inode),
	server);
	rcu_read_unlock();

	if (delegation != NULL)
	nfs_free_delegation(delegation);
	iput(inode);
	goto restart;
	}
	}
	rcu_read_unlock();
	}

	/**
	* nfs_delegations_present - check for existence of delegations
	* @clp: client state handle
	*
	* Returns one if there are any nfs_delegation structures attached
	* to this nfs_client.
	*/
	int nfs_delegations_present(struct nfs_client *clp)
	{
	struct nfs_server *server;
	int ret = 0;

	rcu_read_lock();
	list_for_each_entry_rcu(server, &clp->cl_superblocks, client_link)
	if (!list_empty(&server->delegations)) {
	ret = 1;
	break;
	}
	rcu_read_unlock();
	return ret;
	}

	/**
	* nfs4_copy_delegation_stateid - Copy inode's state ID information
	* @dst: stateid data structure to fill in
	* @inode: inode to check
	* @flags: delegation type requirement
	*
	* Returns "true" and fills in "dst->data" * if inode had a delegation,
	* otherwise "false" is returned.
	*/
	bool nfs4_copy_delegation_stateid(nfs4_stateid dst, struct inode inode,
	fmode_t flags)
	{
	struct nfs_inode *nfsi = NFS_I(inode);
	struct nfs_delegation *delegation;
	bool ret;

	flags &= FMODE_READ\|FMODE_WRITE;
	rcu_read_lock();
	delegation = rcu_dereference(nfsi->delegation);
	ret = (delegation != NULL && (delegation->type & flags) == flags);
	if (ret) {
	nfs4_stateid_copy(dst, &delegation->stateid);
	nfs_mark_delegation_referenced(delegation);
	}
	rcu_read_unlock();
	return ret;
	}