/*
 *  Module for the pnfs nfs4 file layout driver.
 *  Defines all I/O and Policy interface operations, plus code
 *  to register itself with the pNFS client.
 *
 *  Copyright (c) 2002
 *  The Regents of the University of Michigan
 *  All Rights Reserved
 *
 *  Dean Hildebrand <dhildebz@umich.edu>
 *
 *  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/nfs_fs.h>

#include "internal.h"
#include "nfs4filelayout.h"

#define NFSDBG_FACILITY         NFSDBG_PNFS_LD

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dean Hildebrand <dhildebz@umich.edu>");
MODULE_DESCRIPTION("The NFSv4 file layout driver");

#define FILELAYOUT_POLL_RETRY_MAX     (15*HZ)

static loff_t
filelayout_get_dense_offset(struct nfs4_filelayout_segment *flseg,
			    loff_t offset)
{
	u32 stripe_width = flseg->stripe_unit * flseg->dsaddr->stripe_count;
	u64 tmp;

	offset -= flseg->pattern_offset;
	tmp = offset;
	do_div(tmp, stripe_width);

	return tmp * flseg->stripe_unit + do_div(offset, flseg->stripe_unit);
}

/* This function is used by the layout driver to calculate the
 * offset of the file on the dserver based on whether the
 * layout type is STRIPE_DENSE or STRIPE_SPARSE
 */
static loff_t
filelayout_get_dserver_offset(struct pnfs_layout_segment *lseg, loff_t offset)
{
	struct nfs4_filelayout_segment *flseg = FILELAYOUT_LSEG(lseg);

	switch (flseg->stripe_type) {
	case STRIPE_SPARSE:
		return offset;

	case STRIPE_DENSE:
		return filelayout_get_dense_offset(flseg, offset);
	}

	BUG();
}

/* For data server errors we don't recover from */
static void
filelayout_set_lo_fail(struct pnfs_layout_segment *lseg)
{
	if (lseg->pls_range.iomode == IOMODE_RW) {
		dprintk("%s Setting layout IOMODE_RW fail bit\n", __func__);
		set_bit(lo_fail_bit(IOMODE_RW), &lseg->pls_layout->plh_flags);
	} else {
		dprintk("%s Setting layout IOMODE_READ fail bit\n", __func__);
		set_bit(lo_fail_bit(IOMODE_READ), &lseg->pls_layout->plh_flags);
	}
}

static int filelayout_async_handle_error(struct rpc_task *task,
					 struct nfs4_state *state,
					 struct nfs_client *clp,
					 int *reset)
{
	if (task->tk_status >= 0)
		return 0;

	*reset = 0;

	switch (task->tk_status) {
	case -NFS4ERR_BADSESSION:
	case -NFS4ERR_BADSLOT:
	case -NFS4ERR_BAD_HIGH_SLOT:
	case -NFS4ERR_DEADSESSION:
	case -NFS4ERR_CONN_NOT_BOUND_TO_SESSION:
	case -NFS4ERR_SEQ_FALSE_RETRY:
	case -NFS4ERR_SEQ_MISORDERED:
		dprintk("%s ERROR %d, Reset session. Exchangeid "
			"flags 0x%x\n", __func__, task->tk_status,
			clp->cl_exchange_flags);
		nfs4_schedule_session_recovery(clp->cl_session);
		break;
	case -NFS4ERR_DELAY:
	case -NFS4ERR_GRACE:
	case -EKEYEXPIRED:
		rpc_delay(task, FILELAYOUT_POLL_RETRY_MAX);
		break;
	default:
		dprintk("%s DS error. Retry through MDS %d\n", __func__,
			task->tk_status);
		*reset = 1;
		break;
	}
	task->tk_status = 0;
	return -EAGAIN;
}

/* NFS_PROTO call done callback routines */

static int filelayout_read_done_cb(struct rpc_task *task,
				struct nfs_read_data *data)
{
	struct nfs_client *clp = data->ds_clp;
	int reset = 0;

	dprintk("%s DS read\n", __func__);

	if (filelayout_async_handle_error(task, data->args.context->state,
					  data->ds_clp, &reset) == -EAGAIN) {
		dprintk("%s calling restart ds_clp %p ds_clp->cl_session %p\n",
			__func__, data->ds_clp, data->ds_clp->cl_session);
		if (reset) {
			filelayout_set_lo_fail(data->lseg);
			nfs4_reset_read(task, data);
			clp = NFS_SERVER(data->inode)->nfs_client;
		}
		nfs_restart_rpc(task, clp);
		return -EAGAIN;
	}

	return 0;
}

/*
 * Call ops for the async read/write cases
 * In the case of dense layouts, the offset needs to be reset to its
 * original value.
 */
static void filelayout_read_prepare(struct rpc_task *task, void *data)
{
	struct nfs_read_data *rdata = (struct nfs_read_data *)data;

	rdata->read_done_cb = filelayout_read_done_cb;

	if (nfs41_setup_sequence(rdata->ds_clp->cl_session,
				&rdata->args.seq_args, &rdata->res.seq_res,
				0, task))
		return;

	rpc_call_start(task);
}

static void filelayout_read_call_done(struct rpc_task *task, void *data)
{
	struct nfs_read_data *rdata = (struct nfs_read_data *)data;

	dprintk("--> %s task->tk_status %d\n", __func__, task->tk_status);

	/* Note this may cause RPC to be resent */
	rdata->mds_ops->rpc_call_done(task, data);
}

static void filelayout_read_release(void *data)
{
	struct nfs_read_data *rdata = (struct nfs_read_data *)data;

	rdata->mds_ops->rpc_release(data);
}

static int filelayout_write_done_cb(struct rpc_task *task,
				struct nfs_write_data *data)
{
	int reset = 0;

	if (filelayout_async_handle_error(task, data->args.context->state,
					  data->ds_clp, &reset) == -EAGAIN) {
		struct nfs_client *clp;

		dprintk("%s calling restart ds_clp %p ds_clp->cl_session %p\n",
			__func__, data->ds_clp, data->ds_clp->cl_session);
		if (reset) {
			filelayout_set_lo_fail(data->lseg);
			nfs4_reset_write(task, data);
			clp = NFS_SERVER(data->inode)->nfs_client;
		} else
			clp = data->ds_clp;
		nfs_restart_rpc(task, clp);
		return -EAGAIN;
	}

	return 0;
}

static void filelayout_write_prepare(struct rpc_task *task, void *data)
{
	struct nfs_write_data *wdata = (struct nfs_write_data *)data;

	if (nfs41_setup_sequence(wdata->ds_clp->cl_session,
				&wdata->args.seq_args, &wdata->res.seq_res,
				0, task))
		return;

	rpc_call_start(task);
}

static void filelayout_write_call_done(struct rpc_task *task, void *data)
{
	struct nfs_write_data *wdata = (struct nfs_write_data *)data;

	/* Note this may cause RPC to be resent */
	wdata->mds_ops->rpc_call_done(task, data);
}

static void filelayout_write_release(void *data)
{
	struct nfs_write_data *wdata = (struct nfs_write_data *)data;

	wdata->mds_ops->rpc_release(data);
}

struct rpc_call_ops filelayout_read_call_ops = {
	.rpc_call_prepare = filelayout_read_prepare,
	.rpc_call_done = filelayout_read_call_done,
	.rpc_release = filelayout_read_release,
};

struct rpc_call_ops filelayout_write_call_ops = {
	.rpc_call_prepare = filelayout_write_prepare,
	.rpc_call_done = filelayout_write_call_done,
	.rpc_release = filelayout_write_release,
};

static enum pnfs_try_status
filelayout_read_pagelist(struct nfs_read_data *data)
{
	struct pnfs_layout_segment *lseg = data->lseg;
	struct nfs4_pnfs_ds *ds;
	loff_t offset = data->args.offset;
	u32 j, idx;
	struct nfs_fh *fh;
	int status;

	dprintk("--> %s ino %lu pgbase %u req %Zu@%llu\n",
		__func__, data->inode->i_ino,
		data->args.pgbase, (size_t)data->args.count, offset);

	/* Retrieve the correct rpc_client for the byte range */
	j = nfs4_fl_calc_j_index(lseg, offset);
	idx = nfs4_fl_calc_ds_index(lseg, j);
	ds = nfs4_fl_prepare_ds(lseg, idx);
	if (!ds) {
		/* Either layout fh index faulty, or ds connect failed */
		set_bit(lo_fail_bit(IOMODE_RW), &lseg->pls_layout->plh_flags);
		set_bit(lo_fail_bit(IOMODE_READ), &lseg->pls_layout->plh_flags);
		return PNFS_NOT_ATTEMPTED;
	}
	dprintk("%s USE DS:ip %x %hu\n", __func__,
		ntohl(ds->ds_ip_addr), ntohs(ds->ds_port));

	/* No multipath support. Use first DS */
	data->ds_clp = ds->ds_clp;
	fh = nfs4_fl_select_ds_fh(lseg, j);
	if (fh)
		data->args.fh = fh;

	data->args.offset = filelayout_get_dserver_offset(lseg, offset);
	data->mds_offset = offset;

	/* Perform an asynchronous read to ds */
	status = nfs_initiate_read(data, ds->ds_clp->cl_rpcclient,
				   &filelayout_read_call_ops);
	BUG_ON(status != 0);
	return PNFS_ATTEMPTED;
}

/* Perform async writes. */
static enum pnfs_try_status
filelayout_write_pagelist(struct nfs_write_data *data, int sync)
{
	struct pnfs_layout_segment *lseg = data->lseg;
	struct nfs4_pnfs_ds *ds;
	loff_t offset = data->args.offset;
	u32 j, idx;
	struct nfs_fh *fh;
	int status;

	/* Retrieve the correct rpc_client for the byte range */
	j = nfs4_fl_calc_j_index(lseg, offset);
	idx = nfs4_fl_calc_ds_index(lseg, j);
	ds = nfs4_fl_prepare_ds(lseg, idx);
	if (!ds) {
		printk(KERN_ERR "%s: prepare_ds failed, use MDS\n", __func__);
		set_bit(lo_fail_bit(IOMODE_RW), &lseg->pls_layout->plh_flags);
		set_bit(lo_fail_bit(IOMODE_READ), &lseg->pls_layout->plh_flags);
		return PNFS_NOT_ATTEMPTED;
	}
	dprintk("%s ino %lu sync %d req %Zu@%llu DS:%x:%hu\n", __func__,
		data->inode->i_ino, sync, (size_t) data->args.count, offset,
		ntohl(ds->ds_ip_addr), ntohs(ds->ds_port));

	/* We can't handle commit to ds yet */
	if (!FILELAYOUT_LSEG(lseg)->commit_through_mds)
		data->args.stable = NFS_FILE_SYNC;

	data->write_done_cb = filelayout_write_done_cb;
	data->ds_clp = ds->ds_clp;
	fh = nfs4_fl_select_ds_fh(lseg, j);
	if (fh)
		data->args.fh = fh;
	/*
	 * Get the file offset on the dserver. Set the write offset to
	 * this offset and save the original offset.
	 */
	data->args.offset = filelayout_get_dserver_offset(lseg, offset);
	data->mds_offset = offset;

	/* Perform an asynchronous write */
	status = nfs_initiate_write(data, ds->ds_clp->cl_rpcclient,
				    &filelayout_write_call_ops, sync);
	BUG_ON(status != 0);
	return PNFS_ATTEMPTED;
}

/*
 * filelayout_check_layout()
 *
 * Make sure layout segment parameters are sane WRT the device.
 * At this point no generic layer initialization of the lseg has occurred,
 * and nothing has been added to the layout_hdr cache.
 *
 */
static int
filelayout_check_layout(struct pnfs_layout_hdr *lo,
			struct nfs4_filelayout_segment *fl,
			struct nfs4_layoutget_res *lgr,
			struct nfs4_deviceid *id)
{
	struct nfs4_file_layout_dsaddr *dsaddr;
	int status = -EINVAL;
	struct nfs_server *nfss = NFS_SERVER(lo->plh_inode);

	dprintk("--> %s\n", __func__);

	if (fl->pattern_offset > lgr->range.offset) {
		dprintk("%s pattern_offset %lld to large\n",
				__func__, fl->pattern_offset);
		goto out;
	}

	if (!fl->stripe_unit || fl->stripe_unit % PAGE_SIZE) {
		dprintk("%s Invalid stripe unit (%u)\n",
			__func__, fl->stripe_unit);
		goto out;
	}

	/* find and reference the deviceid */
	dsaddr = nfs4_fl_find_get_deviceid(id);
	if (dsaddr == NULL) {
		dsaddr = get_device_info(lo->plh_inode, id);
		if (dsaddr == NULL)
			goto out;
	}
	fl->dsaddr = dsaddr;

	if (fl->first_stripe_index < 0 ||
	    fl->first_stripe_index >= dsaddr->stripe_count) {
		dprintk("%s Bad first_stripe_index %d\n",
				__func__, fl->first_stripe_index);
		goto out_put;
	}

	if ((fl->stripe_type == STRIPE_SPARSE &&
	    fl->num_fh > 1 && fl->num_fh != dsaddr->ds_num) ||
	    (fl->stripe_type == STRIPE_DENSE &&
	    fl->num_fh != dsaddr->stripe_count)) {
		dprintk("%s num_fh %u not valid for given packing\n",
			__func__, fl->num_fh);
		goto out_put;
	}

	if (fl->stripe_unit % nfss->rsize || fl->stripe_unit % nfss->wsize) {
		dprintk("%s Stripe unit (%u) not aligned with rsize %u "
			"wsize %u\n", __func__, fl->stripe_unit, nfss->rsize,
			nfss->wsize);
	}

	status = 0;
out:
	dprintk("--> %s returns %d\n", __func__, status);
	return status;
out_put:
	nfs4_fl_put_deviceid(dsaddr);
	goto out;
}

static void filelayout_free_fh_array(struct nfs4_filelayout_segment *fl)
{
	int i;

	for (i = 0; i < fl->num_fh; i++) {
		if (!fl->fh_array[i])
			break;
		kfree(fl->fh_array[i]);
	}
	kfree(fl->fh_array);
	fl->fh_array = NULL;
}

static void
_filelayout_free_lseg(struct nfs4_filelayout_segment *fl)
{
	filelayout_free_fh_array(fl);
	kfree(fl);
}

static int
filelayout_decode_layout(struct pnfs_layout_hdr *flo,
			 struct nfs4_filelayout_segment *fl,
			 struct nfs4_layoutget_res *lgr,
			 struct nfs4_deviceid *id)
{
	uint32_t *p = (uint32_t *)lgr->layout.buf;
	uint32_t nfl_util;
	int i;

	dprintk("%s: set_layout_map Begin\n", __func__);

	memcpy(id, p, sizeof(*id));
	p += XDR_QUADLEN(NFS4_DEVICEID4_SIZE);
	print_deviceid(id);

	nfl_util = be32_to_cpup(p++);
	if (nfl_util & NFL4_UFLG_COMMIT_THRU_MDS)
		fl->commit_through_mds = 1;
	if (nfl_util & NFL4_UFLG_DENSE)
		fl->stripe_type = STRIPE_DENSE;
	else
		fl->stripe_type = STRIPE_SPARSE;
	fl->stripe_unit = nfl_util & ~NFL4_UFLG_MASK;

	fl->first_stripe_index = be32_to_cpup(p++);
	p = xdr_decode_hyper(p, &fl->pattern_offset);
	fl->num_fh = be32_to_cpup(p++);

	dprintk("%s: nfl_util 0x%X num_fh %u fsi %u po %llu\n",
		__func__, nfl_util, fl->num_fh, fl->first_stripe_index,
		fl->pattern_offset);

	fl->fh_array = kzalloc(fl->num_fh * sizeof(struct nfs_fh *),
			       GFP_KERNEL);
	if (!fl->fh_array)
		return -ENOMEM;

	for (i = 0; i < fl->num_fh; i++) {
		/* Do we want to use a mempool here? */
		fl->fh_array[i] = kmalloc(sizeof(struct nfs_fh), GFP_KERNEL);
		if (!fl->fh_array[i]) {
			filelayout_free_fh_array(fl);
			return -ENOMEM;
		}
		fl->fh_array[i]->size = be32_to_cpup(p++);
		if (sizeof(struct nfs_fh) < fl->fh_array[i]->size) {
			printk(KERN_ERR "Too big fh %d received %d\n",
			       i, fl->fh_array[i]->size);
			filelayout_free_fh_array(fl);
			return -EIO;
		}
		memcpy(fl->fh_array[i]->data, p, fl->fh_array[i]->size);
		p += XDR_QUADLEN(fl->fh_array[i]->size);
		dprintk("DEBUG: %s: fh len %d\n", __func__,
			fl->fh_array[i]->size);
	}

	return 0;
}

static struct pnfs_layout_segment *
filelayout_alloc_lseg(struct pnfs_layout_hdr *layoutid,
		      struct nfs4_layoutget_res *lgr)
{
	struct nfs4_filelayout_segment *fl;
	int rc;
	struct nfs4_deviceid id;

	dprintk("--> %s\n", __func__);
	fl = kzalloc(sizeof(*fl), GFP_KERNEL);
	if (!fl)
		return NULL;

	rc = filelayout_decode_layout(layoutid, fl, lgr, &id);
	if (rc != 0 || filelayout_check_layout(layoutid, fl, lgr, &id)) {
		_filelayout_free_lseg(fl);
		return NULL;
	}
	return &fl->generic_hdr;
}

static void
filelayout_free_lseg(struct pnfs_layout_segment *lseg)
{
	struct nfs4_filelayout_segment *fl = FILELAYOUT_LSEG(lseg);

	dprintk("--> %s\n", __func__);
	nfs4_fl_put_deviceid(fl->dsaddr);
	_filelayout_free_lseg(fl);
}

/*
 * filelayout_pg_test(). Called by nfs_can_coalesce_requests()
 *
 * return 1 :  coalesce page
 * return 0 :  don't coalesce page
 */
int
filelayout_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
		   struct nfs_page *req)
{
	u64 p_stripe, r_stripe;
	u32 stripe_unit;

	if (!pgio->pg_lseg)
		return 1;
	p_stripe = (u64)prev->wb_index << PAGE_CACHE_SHIFT;
	r_stripe = (u64)req->wb_index << PAGE_CACHE_SHIFT;
	stripe_unit = FILELAYOUT_LSEG(pgio->pg_lseg)->stripe_unit;

	do_div(p_stripe, stripe_unit);
	do_div(r_stripe, stripe_unit);

	return (p_stripe == r_stripe);
}

static struct pnfs_layoutdriver_type filelayout_type = {
	.id			= LAYOUT_NFSV4_1_FILES,
	.name			= "LAYOUT_NFSV4_1_FILES",
	.owner			= THIS_MODULE,
	.alloc_lseg		= filelayout_alloc_lseg,
	.free_lseg		= filelayout_free_lseg,
	.pg_test		= filelayout_pg_test,
	.read_pagelist		= filelayout_read_pagelist,
	.write_pagelist		= filelayout_write_pagelist,
};

static int __init nfs4filelayout_init(void)
{
	printk(KERN_INFO "%s: NFSv4 File Layout Driver Registering...\n",
	       __func__);
	return pnfs_register_layoutdriver(&filelayout_type);
}

static void __exit nfs4filelayout_exit(void)
{
	printk(KERN_INFO "%s: NFSv4 File Layout Driver Unregistering...\n",
	       __func__);
	pnfs_unregister_layoutdriver(&filelayout_type);
}

module_init(nfs4filelayout_init);
module_exit(nfs4filelayout_exit);