/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001, 2002 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@cambridge.redhat.com>
 *
 * The original JFFS, from which the design for JFFS2 was derived,
 * was designed and implemented by Axis Communications AB.
 *
 * The contents of this file are subject to the Red Hat eCos Public
 * License Version 1.1 (the "Licence"); you may not use this file
 * except in compliance with the Licence.  You may obtain a copy of
 * the Licence at http://www.redhat.com/
 *
 * Software distributed under the Licence is distributed on an "AS IS"
 * basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.
 * See the Licence for the specific language governing rights and
 * limitations under the Licence.
 *
 * The Original Code is JFFS2 - Journalling Flash File System, version 2
 *
 * Alternatively, the contents of this file may be used under the
 * terms of the GNU General Public License version 2 (the "GPL"), in
 * which case the provisions of the GPL are applicable instead of the
 * above.  If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the RHEPL, indicate your decision by
 * deleting the provisions above and replace them with the notice and
 * other provisions required by the GPL.  If you do not delete the
 * provisions above, a recipient may use your version of this file
 * under either the RHEPL or the GPL.
 *
 * $Id: nodemgmt.c,v 1.2 2002/07/11 17:10:38 sneha Exp $
 *
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/mtd/mtd.h>
#include <linux/interrupt.h>
#include "nodelist.h"

/* Bias the free block calculations to reduce jitter. If we've already
   GC'd enough of the current gc_block that we can fit the remainder
   into the end of the block we're filling, require one fewer free
   block than we otherwise would.
*/
static inline int jffs2_reserve_bias(struct jffs2_sb_info *c)
{
       __u32 gc_ofs;

       if (!c->gcblock)
               return 0;

       D1(if (!c->gcblock->gc_node) BUG());

       if (!c->nextblock)
               return 0;

       gc_ofs = c->gcblock->gc_node->flash_offset & ~(c->sector_size - 1);

       if (gc_ofs > c->nextblock->free_size) {
               /* We're already far enough through the GC to fit the
                  remainder of gc_block into nextblock */
               D1(printk(KERN_DEBUG "jffs2_reserve_bias returns 1. gc_ofs 0x%08x, nextblock->free_size 0x%08x\n", gc_ofs, c->nextblock->free_size));
               return 1;
       }
       return 0;
}

/**
 *	jffs2_reserve_space - request physical space to write nodes to flash
 *	@c: superblock info
 *	@minsize: Minimum acceptable size of allocation
 *	@ofs: Returned value of node offset
 *	@len: Returned value of allocation length
 *	@prio: Allocation type - ALLOC_{NORMAL,DELETION}
 *
 *	Requests a block of physical space on the flash. Returns zero for success
 *	and puts 'ofs' and 'len' into the appriopriate place, or returns -ENOSPC
 *	or other error if appropriate.
 *
 *	If it returns zero, jffs2_reserve_space() also downs the per-filesystem
 *	allocation semaphore, to prevent more than one allocation from being
 *	active at any time. The semaphore is later released by jffs2_commit_allocation()
 *
 *	jffs2_reserve_space() may trigger garbage collection in order to make room
 *	for the requested allocation.
 */

static int jffs2_do_reserve_space(struct jffs2_sb_info *c,  uint32_t minsize, uint32_t *ofs, uint32_t *len);

int jffs2_reserve_space(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs, uint32_t *len, int prio)
{
	int ret = -EAGAIN;
	int blocksneeded = JFFS2_RESERVED_BLOCKS_WRITE;
	/* align it */
	minsize = PAD(minsize);

	if (prio == ALLOC_DELETION)
		blocksneeded = JFFS2_RESERVED_BLOCKS_DELETION;

	D1(printk(KERN_DEBUG "jffs2_reserve_space(): Requested 0x%x bytes\n", minsize));
	down(&c->alloc_sem);

	D1(printk(KERN_DEBUG "jffs2_reserve_space(): alloc sem got\n"));

	spin_lock_bh(&c->erase_completion_lock);

	/* this needs a little more thought */
	while(ret == -EAGAIN) {
		while(c->nr_free_blocks + c->nr_erasing_blocks < blocksneeded - jffs2_reserve_bias(c)) {			
			int ret;

			up(&c->alloc_sem);
			if (c->dirty_size < c->sector_size) {
				D1(printk(KERN_DEBUG "Short on space, but total dirty size 0x%08x < sector size 0x%08x, so -ENOSPC\n", c->dirty_size, c->sector_size));
				spin_unlock_bh(&c->erase_completion_lock);
				return -ENOSPC;
			}
			D1(printk(KERN_DEBUG "Triggering GC pass. nr_free_blocks %d, nr_erasing_blocks %d, free_size 0x%08x, dirty_size 0x%08x, used_size 0x%08x, erasing_size 0x%08x, bad_size 0x%08x (total 0x%08x of 0x%08x)\n",
				  c->nr_free_blocks, c->nr_erasing_blocks, c->free_size, c->dirty_size, c->used_size, c->erasing_size, c->bad_size,
				  c->free_size + c->dirty_size + c->used_size + c->erasing_size + c->bad_size, c->flash_size));
			spin_unlock_bh(&c->erase_completion_lock);
			
			ret = jffs2_garbage_collect_pass(c);
			if (ret)
				return ret;

			if (current->need_resched)
				schedule();

			if (signal_pending(current))
				return -EINTR;

			down(&c->alloc_sem);
			spin_lock_bh(&c->erase_completion_lock);
		}

		ret = jffs2_do_reserve_space(c, minsize, ofs, len);
		if (ret) {
			D1(printk(KERN_DEBUG "jffs2_reserve_space: ret is %d\n", ret));
		}
	}
	spin_unlock_bh(&c->erase_completion_lock);
	if (ret)
		up(&c->alloc_sem);
	return ret;
}

int jffs2_reserve_space_gc(struct jffs2_sb_info *c, uint32_t minsize, uint32_t *ofs, uint32_t *len)
{
	int ret = -EAGAIN;
	minsize = PAD(minsize);

	D1(printk(KERN_DEBUG "jffs2_reserve_space_gc(): Requested 0x%x bytes\n", minsize));

	spin_lock_bh(&c->erase_completion_lock);
	while(ret == -EAGAIN) {
		ret = jffs2_do_reserve_space(c, minsize, ofs, len);
		if (ret) {
		        D1(printk(KERN_DEBUG "jffs2_reserve_space_gc: looping, ret is %d\n", ret));
		}
	}
	spin_unlock_bh(&c->erase_completion_lock);
	return ret;
}

/* Called with alloc sem _and_ erase_completion_lock */
static int jffs2_do_reserve_space(struct jffs2_sb_info *c,  uint32_t minsize, uint32_t *ofs, uint32_t *len)
{
	struct jffs2_eraseblock *jeb = c->nextblock;
	
 restart:
	if (jeb && minsize > jeb->free_size) {
		/* Skip the end of this block and file it as having some dirty space */
		c->dirty_size += jeb->free_size;
		c->free_size -= jeb->free_size;
		jeb->dirty_size += jeb->free_size;
		jeb->free_size = 0;
		D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to dirty_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
			  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
		list_add_tail(&jeb->list, &c->dirty_list);
		c->nextblock = jeb = NULL;
	}
	
	if (!jeb) {
		struct list_head *next;
		/* Take the next block off the 'free' list */

		if (list_empty(&c->free_list)) {

			DECLARE_WAITQUEUE(wait, current);
			
			if (!c->nr_erasing_blocks) {
//			if (list_empty(&c->erasing_list) && list_empty(&c->erase_pending_list) && list_empty(c->erase_complete_list)) {
				/* Ouch. We're in GC, or we wouldn't have got here.
				   And there's no space left. At all. */
				printk(KERN_CRIT "Argh. No free space left for GC. nr_erasing_blocks is %d. nr_free_blocks is %d. (erasingempty: %s, erasependingempty: %s)\n", 
				       c->nr_erasing_blocks, c->nr_free_blocks, list_empty(&c->erasing_list)?"yes":"no", list_empty(&c->erase_pending_list)?"yes":"no");
				return -ENOSPC;
			}
			/* Make sure this can't deadlock. Someone has to start the erases
			   of erase_pending blocks */
			set_current_state(TASK_INTERRUPTIBLE);
			add_wait_queue(&c->erase_wait, &wait);
			D1(printk(KERN_DEBUG "Waiting for erases to complete. erasing_blocks is %d. (erasingempty: %s, erasependingempty: %s)\n", 
				  c->nr_erasing_blocks, list_empty(&c->erasing_list)?"yes":"no", list_empty(&c->erase_pending_list)?"yes":"no"));
			if (!list_empty(&c->erase_pending_list)) {
				D1(printk(KERN_DEBUG "Triggering pending erases\n"));
				jffs2_erase_pending_trigger(c);
			}
			spin_unlock_bh(&c->erase_completion_lock);
			schedule();
			remove_wait_queue(&c->erase_wait, &wait);
			spin_lock_bh(&c->erase_completion_lock);
			if (signal_pending(current)) {
				return -EINTR;
			}
			/* An erase may have failed, decreasing the
			   amount of free space available. So we must
			   restart from the beginning */
			return -EAGAIN;
		}

		next = c->free_list.next;
		list_del(next);
		c->nextblock = jeb = list_entry(next, struct jffs2_eraseblock, list);
		c->nr_free_blocks--;
		if (jeb->free_size != c->sector_size - sizeof(struct jffs2_unknown_node)) {
			printk(KERN_WARNING "Eep. Block 0x%08x taken from free_list had free_size of 0x%08x!!\n", jeb->offset, jeb->free_size);
			goto restart;
		}
	}
	/* OK, jeb (==c->nextblock) is now pointing at a block which definitely has
	   enough space */
	*ofs = jeb->offset + (c->sector_size - jeb->free_size);
	*len = jeb->free_size;
	D1(printk(KERN_DEBUG "jffs2_do_reserve_space(): Giving 0x%x bytes at 0x%x\n", *len, *ofs));
	return 0;
}

/**
 *	jffs2_add_physical_node_ref - add a physical node reference to the list
 *	@c: superblock info
 *	@ofs: physical location of this physical node
 *	@len: length of this physical node
 *	@ino: inode number with which this physical node is associated
 *
 *	Should only be used to report nodes for which space has been allocated 
 *	by jffs2_reserve_space.
 *
 *	Must be called with the alloc_sem held.
 */
 
int jffs2_add_physical_node_ref(struct jffs2_sb_info *c, struct jffs2_raw_node_ref *new, uint32_t len, int dirty)
{
	struct jffs2_eraseblock *jeb;

	len = PAD(len);
	jeb = &c->blocks[(new->flash_offset & ~3) / c->sector_size];
	D1(printk(KERN_DEBUG "jffs2_add_physical_node_ref(): Node at 0x%x, size 0x%x\n", new->flash_offset & ~3, len));
#if 1
	if (jeb != c->nextblock || (new->flash_offset & ~3) != jeb->offset + (c->sector_size - jeb->free_size)) {
		printk(KERN_WARNING "argh. node added in wrong place\n");
		jffs2_free_raw_node_ref(new);
		return -EINVAL;
	}
#endif
	if (!jeb->first_node)
		jeb->first_node = new;
	if (jeb->last_node)
		jeb->last_node->next_phys = new;
	jeb->last_node = new;

	spin_lock_bh(&c->erase_completion_lock);
	jeb->free_size -= len;
	c->free_size -= len;
	if (dirty) {
		new->flash_offset |= 1;
		jeb->dirty_size += len;
		c->dirty_size += len;
	} else {
		jeb->used_size += len;
		c->used_size += len;
	}
	spin_unlock_bh(&c->erase_completion_lock);
	if (!jeb->free_size && !jeb->dirty_size) {
		/* If it lives on the dirty_list, jffs2_reserve_space will put it there */
		D1(printk(KERN_DEBUG "Adding full erase block at 0x%08x to clean_list (free 0x%08x, dirty 0x%08x, used 0x%08x\n",
			  jeb->offset, jeb->free_size, jeb->dirty_size, jeb->used_size));
		list_add_tail(&jeb->list, &c->clean_list);
		c->nextblock = NULL;
	}
	ACCT_SANITY_CHECK(c,jeb);
	ACCT_PARANOIA_CHECK(jeb);

	return 0;
}


void jffs2_complete_reservation(struct jffs2_sb_info *c)
{
	D1(printk(KERN_DEBUG "jffs2_complete_reservation()\n"));
	jffs2_garbage_collect_trigger(c);
	up(&c->alloc_sem);
}

void jffs2_mark_node_obsolete(struct jffs2_sb_info *c, struct jffs2_raw_node_ref *ref)
{
	struct jffs2_eraseblock *jeb;
	int blocknr;
	struct jffs2_unknown_node n;
	int ret;
	size_t retlen;

	if(!ref) {
		printk(KERN_NOTICE "EEEEEK. jffs2_mark_node_obsolete called with NULL node\n");
		return;
	}
	if (ref->flash_offset & 1) {
		D1(printk(KERN_DEBUG "jffs2_mark_node_obsolete called with already obsolete node at 0x%08x\n", ref->flash_offset &~3));
		return;
	}
	blocknr = ref->flash_offset / c->sector_size;
	if (blocknr >= c->nr_blocks) {
		printk(KERN_NOTICE "raw node at 0x%08x is off the end of device!\n", ref->flash_offset);
		BUG();
	}
	jeb = &c->blocks[blocknr];
	if (jeb->used_size < ref->totlen) {
		printk(KERN_NOTICE "raw node of size 0x%08x freed from erase block %d at 0x%08x, but used_size was already 0x%08x\n",
		       ref->totlen, blocknr, ref->flash_offset, jeb->used_size);
		BUG();
	}

	spin_lock_bh(&c->erase_completion_lock);
	jeb->used_size -= ref->totlen;
	jeb->dirty_size += ref->totlen;
	c->used_size -= ref->totlen;
	c->dirty_size += ref->totlen;
	ref->flash_offset |= 1;
	
	ACCT_SANITY_CHECK(c, jeb);

	ACCT_PARANOIA_CHECK(jeb);

	if (jeb == c->nextblock) {
		D2(printk(KERN_DEBUG "Not moving nextblock 0x%08x to dirty/erase_pending list\n", jeb->offset));
	} else if (jeb == c->gcblock) {
		D2(printk(KERN_DEBUG "Not moving gcblock 0x%08x to dirty/erase_pending list\n", jeb->offset));
#if 0 /* We no longer do this here. It can screw the wear levelling. If you have a lot of static
	 data and a few blocks free, and you just create new files and keep deleting/overwriting
	 them, then you'd keep erasing and reusing those blocks without ever moving stuff around.
	 So we leave completely obsoleted blocks on the dirty_list and let the GC delete them 
	 when it finds them there. That way, we still get the 'once in a while, take a clean block'
	 to spread out the flash usage */
	} else if (!jeb->used_size) {
		D1(printk(KERN_DEBUG "Eraseblock at 0x%08x completely dirtied. Removing from (dirty?) list...\n", jeb->offset));
		list_del(&jeb->list);
		D1(printk(KERN_DEBUG "...and adding to erase_pending_list\n"));
		list_add_tail(&jeb->list, &c->erase_pending_list);
		c->nr_erasing_blocks++;
		jffs2_erase_pending_trigger(c);
		//		OFNI_BS_2SFFJ(c)->s_dirt = 1;
		D1(printk(KERN_DEBUG "Done OK\n"));
#endif
	} else if (jeb->dirty_size == ref->totlen) {
		D1(printk(KERN_DEBUG "Eraseblock at 0x%08x is freshly dirtied. Removing from clean list...\n", jeb->offset));
		list_del(&jeb->list);
		D1(printk(KERN_DEBUG "...and adding to dirty_list\n"));
		list_add_tail(&jeb->list, &c->dirty_list);
	}
	spin_unlock_bh(&c->erase_completion_lock);

	if (c->mtd->type != MTD_NORFLASH && c->mtd->type != MTD_RAM)
		return;
	if (jffs2_is_readonly(c))
		return;

	D1(printk(KERN_DEBUG "obliterating obsoleted node at 0x%08x\n", ref->flash_offset &~3));
	ret = jffs2_flash_read(c, ref->flash_offset &~3, sizeof(n), &retlen, (char *)&n);
	if (ret) {
		printk(KERN_WARNING "Read error reading from obsoleted node at 0x%08x: %d\n", ref->flash_offset &~3, ret);
		return;
	}
	if (retlen != sizeof(n)) {
		printk(KERN_WARNING "Short read from obsoleted node at 0x%08x: %d\n", ref->flash_offset &~3, retlen);
		return;
	}
	if (PAD(n.totlen) != PAD(ref->totlen)) {
		printk(KERN_WARNING "Node totlen on flash (0x%08x) != totlen in node ref (0x%08x)\n", n.totlen, ref->totlen);
		return;
	}
	if (!(n.nodetype & JFFS2_NODE_ACCURATE)) {
		D1(printk(KERN_DEBUG "Node at 0x%08x was already marked obsolete (nodetype 0x%04x\n", ref->flash_offset &~3, n.nodetype));
		return;
	}
	n.nodetype &= ~JFFS2_NODE_ACCURATE;
	ret = jffs2_flash_write(c, ref->flash_offset&~3, sizeof(n), &retlen, (char *)&n);
	if (ret) {
		printk(KERN_WARNING "Write error in obliterating obsoleted node at 0x%08x: %d\n", ref->flash_offset &~3, ret);
		return;
	}
	if (retlen != sizeof(n)) {
		printk(KERN_WARNING "Short write in obliterating obsoleted node at 0x%08x: %d\n", ref->flash_offset &~3, retlen);
		return;
	}
}
