/*
 * linux/fs/nfs/callback_proc.c
 *
 * Copyright (C) 2004 Trond Myklebust
 *
 * NFSv4 callback procedures
 */
#include <linux/nfs4.h>
#include <linux/nfs_fs.h>
#include "nfs4_fs.h"
#include "callback.h"
#include "delegation.h"
#include "internal.h"

#ifdef NFS_DEBUG
#define NFSDBG_FACILITY NFSDBG_CALLBACK
#endif
 
__be32 nfs4_callback_getattr(struct cb_getattrargs *args, struct cb_getattrres *res)
{
	struct nfs_client *clp;
	struct nfs_delegation *delegation;
	struct nfs_inode *nfsi;
	struct inode *inode;

	res->bitmap[0] = res->bitmap[1] = 0;
	res->status = htonl(NFS4ERR_BADHANDLE);
	clp = nfs_find_client(args->addr, 4);
	if (clp == NULL)
		goto out;

	dprintk("NFS: GETATTR callback request from %s\n",
		rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));

	inode = nfs_delegation_find_inode(clp, &args->fh);
	if (inode == NULL)
		goto out_putclient;
	nfsi = NFS_I(inode);
	down_read(&nfsi->rwsem);
	delegation = nfsi->delegation;
	if (delegation == NULL || (delegation->type & FMODE_WRITE) == 0)
		goto out_iput;
	res->size = i_size_read(inode);
	res->change_attr = delegation->change_attr;
	if (nfsi->npages != 0)
		res->change_attr++;
	res->ctime = inode->i_ctime;
	res->mtime = inode->i_mtime;
	res->bitmap[0] = (FATTR4_WORD0_CHANGE|FATTR4_WORD0_SIZE) &
		args->bitmap[0];
	res->bitmap[1] = (FATTR4_WORD1_TIME_METADATA|FATTR4_WORD1_TIME_MODIFY) &
		args->bitmap[1];
	res->status = 0;
out_iput:
	up_read(&nfsi->rwsem);
	iput(inode);
out_putclient:
	nfs_put_client(clp);
out:
	dprintk("%s: exit with status = %d\n", __func__, ntohl(res->status));
	return res->status;
}

__be32 nfs4_callback_recall(struct cb_recallargs *args, void *dummy)
{
	struct nfs_client *clp;
	struct inode *inode;
	__be32 res;
	
	res = htonl(NFS4ERR_BADHANDLE);
	clp = nfs_find_client(args->addr, 4);
	if (clp == NULL)
		goto out;

	dprintk("NFS: RECALL callback request from %s\n",
		rpc_peeraddr2str(clp->cl_rpcclient, RPC_DISPLAY_ADDR));

	do {
		struct nfs_client *prev = clp;

		inode = nfs_delegation_find_inode(clp, &args->fh);
		if (inode != NULL) {
			/* Set up a helper thread to actually return the delegation */
			switch(nfs_async_inode_return_delegation(inode, &args->stateid)) {
				case 0:
					res = 0;
					break;
				case -ENOENT:
					if (res != 0)
						res = htonl(NFS4ERR_BAD_STATEID);
					break;
				default:
					res = htonl(NFS4ERR_RESOURCE);
			}
			iput(inode);
		}
		clp = nfs_find_client_next(prev);
		nfs_put_client(prev);
	} while (clp != NULL);
out:
	dprintk("%s: exit with status = %d\n", __func__, ntohl(res));
	return res;
}

#if defined(CONFIG_NFS_V4_1)

/*
 * Validate the sequenceID sent by the server.
 * Return success if the sequenceID is one more than what we last saw on
 * this slot, accounting for wraparound.  Increments the slot's sequence.
 *
 * We don't yet implement a duplicate request cache, so at this time
 * we will log replays, and process them as if we had not seen them before,
 * but we don't bump the sequence in the slot.  Not too worried about it,
 * since we only currently implement idempotent callbacks anyway.
 *
 * We have a single slot backchannel at this time, so we don't bother
 * checking the used_slots bit array on the table.  The lower layer guarantees
 * a single outstanding callback request at a time.
 */
static int
validate_seqid(struct nfs4_slot_table *tbl, u32 slotid, u32 seqid)
{
	struct nfs4_slot *slot;

	dprintk("%s enter. slotid %d seqid %d\n",
		__func__, slotid, seqid);

	if (slotid > NFS41_BC_MAX_CALLBACKS)
		return htonl(NFS4ERR_BADSLOT);

	slot = tbl->slots + slotid;
	dprintk("%s slot table seqid: %d\n", __func__, slot->seq_nr);

	/* Normal */
	if (likely(seqid == slot->seq_nr + 1)) {
		slot->seq_nr++;
		return htonl(NFS4_OK);
	}

	/* Replay */
	if (seqid == slot->seq_nr) {
		dprintk("%s seqid %d is a replay - no DRC available\n",
			__func__, seqid);
		return htonl(NFS4_OK);
	}

	/* Wraparound */
	if (seqid == 1 && (slot->seq_nr + 1) == 0) {
		slot->seq_nr = 1;
		return htonl(NFS4_OK);
	}

	/* Misordered request */
	return htonl(NFS4ERR_SEQ_MISORDERED);
}

/*
 * Returns a pointer to a held 'struct nfs_client' that matches the server's
 * address, major version number, and session ID.  It is the caller's
 * responsibility to release the returned reference.
 *
 * Returns NULL if there are no connections with sessions, or if no session
 * matches the one of interest.
 */
 static struct nfs_client *find_client_with_session(
	const struct sockaddr *addr, u32 nfsversion,
	struct nfs4_sessionid *sessionid)
{
	struct nfs_client *clp;

	clp = nfs_find_client(addr, 4);
	if (clp == NULL)
		return NULL;

	do {
		struct nfs_client *prev = clp;

		if (clp->cl_session != NULL) {
			if (memcmp(clp->cl_session->sess_id.data,
					sessionid->data,
					NFS4_MAX_SESSIONID_LEN) == 0) {
				/* Returns a held reference to clp */
				return clp;
			}
		}
		clp = nfs_find_client_next(prev);
		nfs_put_client(prev);
	} while (clp != NULL);

	return NULL;
}

/* FIXME: referring calls should be processed */
unsigned nfs4_callback_sequence(struct cb_sequenceargs *args,
				struct cb_sequenceres *res)
{
	struct nfs_client *clp;
	int i, status;

	for (i = 0; i < args->csa_nrclists; i++)
		kfree(args->csa_rclists[i].rcl_refcalls);
	kfree(args->csa_rclists);

	status = htonl(NFS4ERR_BADSESSION);
	clp = find_client_with_session(args->csa_addr, 4, &args->csa_sessionid);
	if (clp == NULL)
		goto out;

	status = validate_seqid(&clp->cl_session->bc_slot_table,
				args->csa_slotid, args->csa_sequenceid);
	if (status)
		goto out_putclient;

	memcpy(&res->csr_sessionid, &args->csa_sessionid,
	       sizeof(res->csr_sessionid));
	res->csr_sequenceid = args->csa_sequenceid;
	res->csr_slotid = args->csa_slotid;
	res->csr_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;
	res->csr_target_highestslotid = NFS41_BC_MAX_CALLBACKS - 1;

out_putclient:
	nfs_put_client(clp);
out:
	dprintk("%s: exit with status = %d\n", __func__, ntohl(status));
	res->csr_status = status;
	return res->csr_status;
}

#endif /* CONFIG_NFS_V4_1 */