/*
 * OBDFS Super operations - also used for Lustre file system
 *
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 * Copryright (C) 1999 Stelias Computing Inc. <braam@stelias.com>
 * Copryright (C) 1999 Seagate Technology Inc.
 *
 */
#define __NO_VERSION__
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/fs.h>
#include <linux/malloc.h>
#include <linux/locks.h>
#include <linux/errno.h>
#include <linux/swap.h>
#include <linux/smp_lock.h>
#include <linux/vmalloc.h>
#include <linux/blkdev.h>
#include <linux/sysrq.h>
#include <linux/file.h>
#include <linux/init.h>
#include <linux/quotaops.h>
#include <linux/iobuf.h>
#include <linux/highmem.h>

#include <asm/uaccess.h>
#include <asm/io.h>
#include <asm/bitops.h>
#include <asm/mmu_context.h>

#include <linux/obd_support.h>
#include <linux/obd_class.h>
#include <linux/obdfs.h>



struct {
	int nfract;  /* Percentage of buffer cache dirty to 
			activate bdflush */
	int ndirty;  /* Maximum number of dirty blocks to write out per
			wake-cycle */
	int nrefill; /* Number of clean buffers to try to obtain
				each time we call refill */
	int nref_dirt; /* Dirty buffer threshold for activating bdflush
			  when trying to refill buffers. */
	int interval; /* jiffies delay between kupdate flushes */
	int age_buffer;  /* Time for normal buffer to age before we flush it */
	int age_super;  /* Time for superblock to age before we flush it */
} pupd_prm = {40, 500, 64, 256, 5*HZ, 30*HZ, 5*HZ }; 


static int obdfs_enqueue_pages(struct inode *inode, struct obdo **obdo,
			       int nr_slots, struct page **pages, char **bufs,
			       obd_size *counts, obd_off *offsets,
			       obd_flag *flag, int check_time)
{
	struct list_head *page_list = obdfs_iplist(inode);
	struct list_head *tmp;
	int i = 0;

	ENTRY;
	/* if there are no pages, remove from super block list */
	if (list_empty(obdfs_iplist(inode))) {
		list_del(obdfs_islist(inode));
		/* we check for "empty" on this animal: must init it! */
		INIT_LIST_HEAD(obdfs_islist(inode));
		CDEBUG(D_INODE, "empty list\n");
		EXIT;
		return 0;
	}

	*obdo = obdo_fromid(IID(inode), inode->i_ino, OBD_MD_FLNOTOBD);
	if ( IS_ERR(*obdo) ) {
		EXIT;
		return PTR_ERR(*obdo);
	}

	obdfs_from_inode(*obdo, inode);
	*flag = OBD_BRW_CREATE;

	tmp = page_list;
	while ( (tmp = tmp->next) != page_list && (i < nr_slots) ) {
		struct obdfs_pgrq *req;
		struct page *page;
		
		req = list_entry(tmp, struct obdfs_pgrq, rq_plist);
		/* remove request from list before write to avoid conflict */
		obdfs_pgrq_del(req);
		page = req->rq_page;

		if ( !page  ) {
			CDEBUG(D_INODE, "no page \n");
			EXIT;
			return 0;
		}

		if (check_time && 
		    req->rq_jiffies > (jiffies - pupd_prm.age_buffer))
			continue;
		
		CDEBUG(D_INODE, "adding page %p to vector\n", page);
		bufs[i] = (char *)page_address(page);
		pages[i] = page;
		counts[i] = PAGE_SIZE;
		offsets[i] = ((obd_off)page->index) << PAGE_SHIFT;
		i++;
	}

	/* If no more pages for this inode, remove from superblock list */
	if ( list_empty(obdfs_iplist(inode)) )
		list_del(obdfs_islist(inode));

	EXIT;
	return i;  
}


/* Remove writeback requests for the superblock */
int obdfs_flush_reqs(struct list_head *inode_list, int flush_inode,
		     int check_time)
{
	struct list_head *tmp = inode_list;
	obd_count	  num_io = 0;
	obd_count         num_obdos = 0;
	struct inode	 *inodes[MAX_IOVEC];
	struct obdo	 *obdos[MAX_IOVEC];
	struct page	 *pages[MAX_IOVEC];
	char		 *bufs[MAX_IOVEC];
	obd_size	  counts[MAX_IOVEC];
	obd_off		  offsets[MAX_IOVEC];
	obd_flag	  flags[MAX_IOVEC];
	obd_count         bufs_per_obdo[MAX_IOVEC];
	int		  err = 0;
	int i;

	ENTRY;

	if (!inode_list) {
		CDEBUG(D_INODE, "no list\n");
		EXIT;
		return 0;
	}

	if ( list_empty(inode_list)) {
		CDEBUG(D_INODE, "list empty\n");
		EXIT;
		return 0;
	}


	/* add all of the outstanding pages to a write vector, and write it */
	while ( (tmp = tmp->next) != inode_list ) {
		struct obdfs_inode_info *ii;
		int res;

		ii = list_entry(tmp, struct obdfs_inode_info, oi_inodes);
		inodes[num_obdos] = list_entry(ii, struct inode, u);

		res = obdfs_enqueue_pages(inodes[num_obdos], &obdos[num_obdos],
					  MAX_IOVEC - num_io, &pages[num_io],
					  &bufs[num_io], &counts[num_io],
					  &offsets[num_io], &flags[num_obdos],1);
		if ( res < 0 ) {
			return -EIO;
		}
		
		bufs_per_obdo[num_obdos] = res;
		num_io += res;
		num_obdos++;

		if ( num_io == MAX_IOVEC ) {
			err = obdfs_do_vec_wr(inodes[0]->i_sb, num_io,
					      num_obdos, obdos, bufs_per_obdo,
					      pages, bufs, counts, offsets,
					      flags);
			for (i = 0 ; i < num_obdos ; i++) {
				obdfs_to_inode(inodes[i], obdos[i]);
				obdo_free(obdos[i]);
			}
			if ( err ) {
				EXIT;
				goto ERR;
			}
			num_io = 0;
			num_obdos = 0;
		}
	} 

	/* flush any remaining I/Os */
	if ( num_io ) {
		err = obdfs_do_vec_wr(inodes[0]->i_sb, num_io, num_obdos, 
				      obdos, bufs_per_obdo, pages, bufs,
				      counts, offsets, flags);
		for (i = 0 ; i < num_obdos ; i++) {
			obdfs_to_inode(inodes[i], obdos[i]);
			obdo_free(obdos[i]);
		}
	}
	EXIT;
ERR:

	return err;
} /* obdfs_remove_pages_from_cache */


static void obdfs_flush_dirty_pages(int check_time)
{
	struct list_head *sl;

	sl = &obdfs_super_list;
	while ( (sl = sl->next) != &obdfs_super_list ) {
		struct obdfs_sb_info *sbi = 
			list_entry(sl, struct obdfs_sb_info, osi_list);

		/* walk write requests here, use the sb, check the time */
		obdfs_flush_reqs(&sbi->osi_inodes, 0, 1);
	}

#if 0
	/* again, but now we wait for completion */
	sl = &obdfs_super_list;
	while ( (sl = sl->next) != &obdfs_super_list ) {
		struct obdfs_sb_info *sbi = 
			list_entry(sl, struct obdfs_sb_info, sl_chain);

		/* walk write requests here */
		obdfs_flush_reqs(&sbi->osi_pages, 0, check_time);
	}
#endif
}


static struct task_struct *pupdated;


static int pupdate(void *unused) 
{
	struct task_struct * tsk = current;
	int interval;
	
	pupdated = current;

	exit_files(current);
	exit_mm(current);

	tsk->session = 1;
	tsk->pgrp = 1;
	sprintf(tsk->comm, "pupdated");
	pupdated = current;

	printk("pupdated activated...\n");

	/* sigstop and sigcont will stop and wakeup pupdate */
	spin_lock_irq(&tsk->sigmask_lock);
	sigfillset(&tsk->blocked);
	siginitsetinv(&tsk->blocked, sigmask(SIGTERM));
	recalc_sigpending(tsk);
	spin_unlock_irq(&tsk->sigmask_lock);

	for (;;) {
		/* update interval */
		interval = pupd_prm.interval;
		if (interval)
		{
			tsk->state = TASK_INTERRUPTIBLE;
			schedule_timeout(interval);
		}
		else
		{
		stop_pupdate:
			tsk->state = TASK_STOPPED;
			/* MOD_DEC_USE_COUNT; */
			printk("pupdated stopped...\n");
			return 0;
		}
		/* check for sigstop */
		if (signal_pending(tsk))
		{
			int stopped = 0;
			spin_lock_irq(&tsk->sigmask_lock);
			if (sigismember(&tsk->signal, SIGTERM))
			{
				sigdelset(&tsk->signal, SIGTERM);
				stopped = 1;
			}
			recalc_sigpending(tsk);
			spin_unlock_irq(&tsk->sigmask_lock);
			if (stopped)
				goto stop_pupdate;
		}
		/* asynchronous setattr etc for the future ... */
		/* flush_inodes(); */
		CDEBUG(D_INODE, "about to flush pages...\n");
		/*
		obdfs_flush_dirty_pages(1);
		*/
		CDEBUG(D_INODE, "done flushing pages...\n");
	}
}


int flushd_init(void)
{
	/*
	kernel_thread(bdflush, NULL, CLONE_FS | CLONE_FILES | CLONE_SIGHAND);
	 */
	/* MOD_INC_USE_COUNT; */
	kernel_thread(pupdate, NULL, 0);
	printk("flushd inited\n");
	return 0;
}

int flushd_cleanup(void)
{
	/* this should deliver a signal to */
	

	/* XXX Andreas, we will do this later, for now, you must kill
	   pupdated with a SIGTERM from userland, before unloading obdfs.o
	*/
	if (pupdated) {
		/* then let it run at least once, before continuing */

		/* XXX need to do something like this here:
		send_sig(SIGTERM, current, 0);
		 */
		1;
	}

	/* not reached */
	return 0;

}