path: root/fs/nfs/delegation.c

// SPDX-License-Identifier: GPL-2.0-only
/*
 * 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/iversion.h>

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

#include "nfs4_fs.h"
#include "nfs4session.h"
#include "delegation.h"
#include "internal.h"
#include "nfs4trace.h"

#define NFS_DEFAULT_DELEGATION_WATERMARK (5000U)

static unsigned nfs_delegation_watermark = NFS_DEFAULT_DELEGATION_WATERMARK;
module_param_named(delegation_watermark, nfs_delegation_watermark, uint, 0644);

static struct hlist_head *nfs_delegation_hash(struct nfs_server *server,
		const struct nfs_fh *fhandle)
{
	return server->delegation_hash_table +
		(nfs_fhandle_hash(fhandle) & server->delegation_hash_mask);
}

static void __nfs_free_delegation(struct nfs_delegation *delegation)
{
	put_cred(delegation->cred);
	delegation->cred = NULL;
	kfree_rcu(delegation, rcu);
}

static void nfs_mark_delegation_revoked(struct nfs_server *server,
		struct nfs_delegation *delegation)
{
	if (!test_and_set_bit(NFS_DELEGATION_REVOKED, &delegation->flags)) {
		delegation->stateid.type = NFS4_INVALID_STATEID_TYPE;
		atomic_long_dec(&server->nr_active_delegations);
		if (!test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
			nfs_clear_verifier_delegated(delegation->inode);
	}
}

static struct nfs_delegation *nfs_get_delegation(struct nfs_delegation *delegation)
{
	refcount_inc(&delegation->refcount);
	return delegation;
}

static void nfs_put_delegation(struct nfs_delegation *delegation)
{
	if (refcount_dec_and_test(&delegation->refcount))
		__nfs_free_delegation(delegation);
}

static void nfs_free_delegation(struct nfs_server *server,
		struct nfs_delegation *delegation)
{
	nfs_mark_delegation_revoked(server, delegation);
	nfs_put_delegation(delegation);
}

/**
 * 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);
}

static void nfs_mark_return_delegation(struct nfs_server *server,
				       struct nfs_delegation *delegation)
{
	set_bit(NFS_DELEGATION_RETURN, &delegation->flags);
	set_bit(NFS4SERV_DELEGRETURN, &server->delegation_flags);
	set_bit(NFS4CLNT_DELEGRETURN, &server->nfs_client->cl_state);
}

static bool nfs4_is_valid_delegation(const struct nfs_delegation *delegation,
				     fmode_t type)
{
	if (delegation != NULL && (delegation->type & type) == type &&
	    !test_bit(NFS_DELEGATION_REVOKED, &delegation->flags) &&
	    !test_bit(NFS_DELEGATION_RETURNING, &delegation->flags))
		return true;
	return false;
}

struct nfs_delegation *nfs4_get_valid_delegation(const struct inode *inode)
{
	struct nfs_delegation *delegation;

	delegation = rcu_dereference(NFS_I(inode)->delegation);
	if (nfs4_is_valid_delegation(delegation, 0))
		return delegation;
	return NULL;
}

static int nfs4_do_check_delegation(struct inode *inode, fmode_t type,
				    int flags, bool mark)
{
	struct nfs_delegation *delegation;
	int ret = 0;

	type &= FMODE_READ|FMODE_WRITE;
	rcu_read_lock();
	delegation = rcu_dereference(NFS_I(inode)->delegation);
	if (nfs4_is_valid_delegation(delegation, type)) {
		if (mark)
			nfs_mark_delegation_referenced(delegation);
		ret = 1;
		if ((flags & NFS_DELEGATION_FLAG_TIME) &&
		    !test_bit(NFS_DELEGATION_DELEGTIME, &delegation->flags))
			ret = 0;
	}
	rcu_read_unlock();
	return ret;
}
/**
 * nfs4_have_delegation - check if inode has a delegation, mark it
 * NFS_DELEGATION_REFERENCED if there is one.
 * @inode: inode to check
 * @type: delegation types to check for
 * @flags: various modifiers
 *
 * Returns one if inode has the indicated delegation, otherwise zero.
 */
int nfs4_have_delegation(struct inode *inode, fmode_t type, int flags)
{
	return nfs4_do_check_delegation(inode, type, flags, true);
}

/*
 * nfs4_check_delegation - check if inode has a delegation, do not mark
 * NFS_DELEGATION_REFERENCED if it has one.
 */
int nfs4_check_delegation(struct inode *inode, fmode_t type)
{
	return nfs4_do_check_delegation(inode, type, 0, false);
}

static int nfs_delegation_claim_locks(struct nfs4_state *state, const nfs4_stateid *stateid)
{
	struct inode *inode = state->inode;
	struct file_lock *fl;
	struct file_lock_context *flctx = locks_inode_context(inode);
	struct list_head *list;
	int status = 0;

	if (flctx == NULL)
		goto out;

	list = &flctx->flc_posix;
	spin_lock(&flctx->flc_lock);
restart:
	for_each_file_lock(fl, list) {
		if (nfs_file_open_context(fl->c.flc_file)->state != state)
			continue;
		spin_unlock(&flctx->flc_lock);
		status = nfs4_lock_delegation_recall(fl, state, stateid);
		if (status < 0)
			goto out;
		spin_lock(&flctx->flc_lock);
	}
	if (list == &flctx->flc_posix) {
		list = &flctx->flc_flock;
		goto restart;
	}
	spin_unlock(&flctx->flc_lock);
out:
	return status;
}