/*
 * JFFS3 -- Journalling Flash File System, Version 3.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * JFFS2 Id: readinode.c,v 1.117 2004/11/20 18:06:54 dwmw2  Exp
 * $Id: readinode.c,v 3.8 2005/01/05 16:19:00 dedekind Exp $
 *
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/crc32.h>
#include <linux/pagemap.h>
#include <linux/mtd/mtd.h>
#include <linux/compiler.h>
#include "nodelist.h"

static int jffs3_add_frag_to_fragtree(struct jffs3_sb_info *c, struct rb_root *list, struct jffs3_node_frag *newfrag);

static void jffs3_obsolete_node_frag(struct jffs3_sb_info *c, struct jffs3_node_frag *this)
{
	if (this->node) {
		this->node->frags--;
		if (!this->node->frags) {
			/* The node has no valid frags left. It's totally obsoleted */
			DBG_BI(2, "Marking old node @0x%08x (0x%04x-0x%04x) obsolete\n",
				  ref_offset(this->node->raw), this->node->ofs, this->node->ofs+this->node->size);
			jffs3_mark_node_obsolete(c, this->node->raw);
			jffs3_free_full_dnode(this->node);
		} else {
			DBG_BI(2, "Marking old node @0x%08x (0x%04x-0x%04x) REF_NORMAL. frags is %d\n",
				  ref_offset(this->node->raw), this->node->ofs, this->node->ofs+this->node->size,
				  this->node->frags);
			mark_ref_normal(this->node->raw);
		}

	}
	jffs3_free_node_frag(this);
}

/* Given an inode, probably with existing list of fragments, add the new node
 * to the fragment list.
 */
int jffs3_add_full_dnode_to_inode(struct jffs3_sb_info *c, struct jffs3_inode_info *f, struct jffs3_full_dnode *fn)
{
	int ret;
	struct jffs3_node_frag *newfrag;

	DBG_BI(1, "enter, ino #%u, f %p, fn %p)\n", f->inocache->ino, f, fn);

	newfrag = jffs3_alloc_node_frag();
	if (unlikely(!newfrag))
		return -ENOMEM;

	DBG_BI(2, "adding node %04x-%04x @0x%08x on flash, newfrag *%p\n",
		  fn->ofs, fn->ofs+fn->size, ref_offset(fn->raw), newfrag);

	if (unlikely(!fn->size)) {
		jffs3_free_node_frag(newfrag);
		return 0;
	}

	newfrag->ofs = fn->ofs;
	newfrag->size = fn->size;
	newfrag->node = fn;
	newfrag->node->frags = 1;

	ret = jffs3_add_frag_to_fragtree(c, &f->fragtree, newfrag);
	if (ret)
		return ret;

	/* If we now share a page with other nodes, mark either previous
	   or next node REF_NORMAL, as appropriate.  */
	if (newfrag->ofs & (PAGE_CACHE_SIZE-1)) {
		struct jffs3_node_frag *prev = frag_prev(newfrag);

		mark_ref_normal(fn->raw);
		/* If we don't start at zero there's _always_ a previous */
		if (prev->node)
			mark_ref_normal(prev->node->raw);
	}

	if ((newfrag->ofs+newfrag->size) & (PAGE_CACHE_SIZE-1)) {
		struct jffs3_node_frag *next = frag_next(newfrag);

		if (next) {
			mark_ref_normal(fn->raw);
			if (next->node)
				mark_ref_normal(next->node->raw);
		}
	}

	if (DEBUG2) {
		DBG_BI(2, "The fragment tree dump:\n");
		jffs3_dbg_dump_frag_list(f);
	}

	return 0;
}

/* Doesn't set inode->i_size */
static int jffs3_add_frag_to_fragtree(struct jffs3_sb_info *c, struct rb_root *list, struct jffs3_node_frag *newfrag)
{
	struct jffs3_node_frag *this;
	uint32_t lastend;

	/* Skip all the nodes which are completed before this one starts */
	this = jffs3_lookup_node_frag(list, newfrag->node->ofs);

	if (this) {
		DBG_BI(2, "Lookup gave frag 0x%04x-0x%04x; phys 0x%08x (*%p)\n",
			  this->ofs, this->ofs+this->size,
			  this->node ? (ref_offset(this->node->raw)) : 0xffffffff, this);
		lastend = this->ofs + this->size;
	} else {
		DBG_BI(2, "Lookup gave no frag\n");
		lastend = 0;
	}

	/* See if we ran off the end of the list */
	if (lastend <= newfrag->ofs) {
		/* We did */

		/* Check if 'this' node was on the same page as the new node.
		   If so, both 'this' and the new node get marked REF_NORMAL so
		   the GC can take a look.
		*/
		if (lastend && (lastend-1) >> PAGE_CACHE_SHIFT == newfrag->ofs >> PAGE_CACHE_SHIFT) {
			if (this->node)
				mark_ref_normal(this->node->raw);
			mark_ref_normal(newfrag->node->raw);
		}

		if (lastend < newfrag->node->ofs) {
			/* ... and we need to put a hole in before the new node */
			struct jffs3_node_frag *holefrag = jffs3_alloc_node_frag();
			if (!holefrag) {
				jffs3_free_node_frag(newfrag);
				return -ENOMEM;
			}
			holefrag->ofs = lastend;
			holefrag->size = newfrag->node->ofs - lastend;
			holefrag->node = NULL;
			if (this) {
				/* By definition, the 'this' node has no right-hand child,
				   because there are no frags with offset greater than it.
				   So that's where we want to put the hole */
				DBG_BI(2, "Adding hole frag (%p) on right of node at (%p)\n", holefrag, this);
				rb_link_node(&holefrag->rb, &this->rb, &this->rb.rb_right);
			} else {
				DBG_BI(2, "Adding hole frag (%p) at root of tree\n", holefrag);
				rb_link_node(&holefrag->rb, NULL, &list->rb_node);
			}
			rb_insert_color(&holefrag->rb, list);
			this = holefrag;
		}
		if (this) {
			/* By definition, the 'this' node has no right-hand child,
			   because there are no frags with offset greater than it.
			   So that's where we want to put the hole */
			DBG_BI(2, "Adding new frag (%p) on right of node at (%p)\n", newfrag, this);
			rb_link_node(&newfrag->rb, &this->rb, &this->rb.rb_right);
		} else {
			DBG_BI(2, "Adding new frag (%p) at root of tree\n", newfrag);
			rb_link_node(&newfrag->rb, NULL, &list->rb_node);
		}
		rb_insert_color(&newfrag->rb, list);
		return 0;
	}

	DBG_BI(2, "dealing with frag 0x%04x-0x%04x; phys 0x%08x (*%p)\n",
		  this->ofs, this->ofs+this->size,
		  this->node ? (ref_offset(this->node->raw)) : 0xffffffff, this);

	/* OK. 'this' is pointing at the first frag that newfrag->ofs at least partially obsoletes,
	 * - i.e. newfrag->ofs < this->ofs+this->size && newfrag->ofs >= this->ofs
	 */
	if (newfrag->ofs > this->ofs) {
		/* This node isn't completely obsoleted. The start of it remains valid */

		/* Mark the new node and the partially covered node REF_NORMAL -- let
		   the GC take a look at them */
		mark_ref_normal(newfrag->node->raw);
		if (this->node)
			mark_ref_normal(this->node->raw);

		if (this->ofs + this->size > newfrag->ofs + newfrag->size) {
			/* The new node splits 'this' frag into two */
			struct jffs3_node_frag *newfrag2 = jffs3_alloc_node_frag();
			if (!newfrag2) {
				jffs3_free_node_frag(newfrag);
				return -ENOMEM;
			}

			if (DEBUG2) {
				DBG_BI(2, "split old frag 0x%04x-0x%04x -->", this->ofs, this->ofs+this->size);
				if (this->node)
					DBG_BI(2, "phys 0x%08x\n", ref_offset(this->node->raw));
				else
					DBG_BI(2, "hole\n");
			}

			/* New second frag pointing to this's node */
			newfrag2->ofs = newfrag->ofs + newfrag->size;
			newfrag2->size = (this->ofs+this->size) - newfrag2->ofs;
			newfrag2->node = this->node;
			if (this->node)
				this->node->frags++;

			/* Adjust size of original 'this' */
			this->size = newfrag->ofs - this->ofs;

			/* Now, we know there's no node with offset
			   greater than this->ofs but smaller than
			   newfrag2->ofs or newfrag->ofs, for obvious
			   reasons. So we can do a tree insert from
			   'this' to insert newfrag, and a tree insert
			   from newfrag to insert newfrag2. */
			jffs3_fragtree_insert(newfrag, this);
			rb_insert_color(&newfrag->rb, list);

			jffs3_fragtree_insert(newfrag2, newfrag);
			rb_insert_color(&newfrag2->rb, list);

			return 0;
		}
		/* New node just reduces 'this' frag in size, doesn't split it */
		this->size = newfrag->ofs - this->ofs;

		/* Again, we know it lives down here in the tree */
		jffs3_fragtree_insert(newfrag, this);
		rb_insert_color(&newfrag->rb, list);
	} else {
		/* New frag starts at the same point as 'this' used to. Replace
		   it in the tree without doing a delete and insertion */
		DBG_BI(2, "Inserting newfrag (*%p),%d-%d in before 'this' (*%p),%d-%d\n",
			  newfrag, newfrag->ofs, newfrag->ofs+newfrag->size,
			  this, this->ofs, this->ofs+this->size);

		rb_replace_node(&this->rb, &newfrag->rb, list);

		if (newfrag->ofs + newfrag->size >= this->ofs+this->size) {
			DBG_BI(2, "Obsoleting node frag %p (%x-%x)\n", this, this->ofs, this->ofs+this->size);
			jffs3_obsolete_node_frag(c, this);
		} else {
			this->ofs += newfrag->size;
			this->size -= newfrag->size;

			jffs3_fragtree_insert(this, newfrag);
			rb_insert_color(&this->rb, list);
			return 0;
		}
	}
	/* OK, now we have newfrag added in the correct place in the tree, but
	   frag_next(newfrag) may be a fragment which is overlapped by it
	*/
	while ((this = frag_next(newfrag)) && newfrag->ofs + newfrag->size >= this->ofs + this->size) {
		/* 'this' frag is obsoleted completely. */
		DBG_BI(2, "Obsoleting node frag %p (%x-%x) and removing from tree\n",
				this, this->ofs, this->ofs+this->size);
		rb_erase(&this->rb, list);
		jffs3_obsolete_node_frag(c, this);
	}
	/* Now we're pointing at the first frag which isn't totally obsoleted by
	   the new frag */

	if (!this || newfrag->ofs + newfrag->size == this->ofs) {
		return 0;
	}
	/* Still some overlap but we don't need to move it in the tree */
	this->size = (this->ofs + this->size) - (newfrag->ofs + newfrag->size);
	this->ofs = newfrag->ofs + newfrag->size;

	/* And mark them REF_NORMAL so the GC takes a look at them */
	if (this->node)
		mark_ref_normal(this->node->raw);
	mark_ref_normal(newfrag->node->raw);

	return 0;
}

void jffs3_truncate_fraglist (struct jffs3_sb_info *c, struct rb_root *list, uint32_t size)
{
	struct jffs3_node_frag *frag = jffs3_lookup_node_frag(list, size);

	DBG_BI(1, "Truncating fraglist to 0x%08x bytes\n", size);

	/* We know frag->ofs <= size. That's what lookup does for us */
	if (frag && frag->ofs != size) {
		if (frag->ofs+frag->size >= size) {
			DBG_BI(1, "Truncating frag 0x%08x-0x%08x\n", frag->ofs, frag->ofs+frag->size);
			frag->size = size - frag->ofs;
		}
		frag = frag_next(frag);
	}
	while (frag && frag->ofs >= size) {
		struct jffs3_node_frag *next = frag_next(frag);

		DBG_BI(1, "Removing frag 0x%08x-0x%08x\n", frag->ofs, frag->ofs+frag->size);
		frag_erase(frag, list);
		jffs3_obsolete_node_frag(c, frag);
		frag = next;
	}
}

/* Scan the list of all nodes present for this ino, build map of versions, etc. */

static int jffs3_do_read_inode_internal(struct jffs3_sb_info *c,
					struct jffs3_inode_info *f,
					struct jffs3_raw_inode *latest_node);

int jffs3_do_read_inode(struct jffs3_sb_info *c, struct jffs3_inode_info *f,
			uint32_t ino, struct jffs3_raw_inode *latest_node)
{
	DBG_RI(2, "Read ino #%u\n", ino);

 retry_inocache:
	spin_lock(&c->inocache_lock);
	f->inocache = jffs3_get_ino_cache(c, ino);

	DBG_RI(2, "Got inocache at %p\n", f->inocache);

	if (f->inocache) {
		/* Check its state. We may need to wait before we can use it */
		switch(f->inocache->state) {
		case INO_STATE_UNCHECKED:
		case INO_STATE_CHECKEDABSENT:
			f->inocache->state = INO_STATE_READING;
			break;

		case INO_STATE_CHECKING:
		case INO_STATE_GC:
			/* If it's in either of these states, we need
			   to wait for whoever's got it to finish and
			   put it back. */
			DBG_RI(1, "waiting for ino #%u in state %d\n",
				  ino, f->inocache->state);
			sleep_on_spinunlock(&c->inocache_wq, &c->inocache_lock);
			goto retry_inocache;

		case INO_STATE_READING:
		case INO_STATE_PRESENT:
			/* Eep. This should never happen. It can
			happen if Linux calls read_inode() again
			before clear_inode() has finished though. */
			WARNING_MSG("Eep. Trying to read_inode #%u when it's "
					"already in state %d!\n", ino, f->inocache->state);
			/* Fail. That's probably better than allowing it to succeed */
			f->inocache = NULL;
			break;

		default:
			BUG();
		}
	}
	spin_unlock(&c->inocache_lock);

	if (!f->inocache && ino == 1) {
		/* Special case - no root inode on medium */
		f->inocache = jffs3_alloc_inode_cache();
		if (!f->inocache) {
			WARNING_MSG("Cannot allocate inocache for root inode\n");
			return -ENOMEM;
		}
		DBG_RI(1, "Creating inocache for root inode\n");
		memset(f->inocache, 0, sizeof(struct jffs3_inode_cache));
		f->inocache->ino = f->inocache->nlink = 1;
		f->inocache->nodes = (struct jffs3_raw_node_ref *)f->inocache;
		f->inocache->state = INO_STATE_READING;
		jffs3_add_ino_cache(c, f->inocache);
	}
	if (!f->inocache) {
		WARNING_MSG("on nonexistent ino %u\n", ino);
		return -ENOENT;
	}

	return jffs3_do_read_inode_internal(c, f, latest_node);
}

int jffs3_do_crccheck_inode(struct jffs3_sb_info *c, struct jffs3_inode_cache *ic)
{
	struct jffs3_raw_inode n;
	struct jffs3_inode_info *f = kmalloc(sizeof(*f), GFP_KERNEL);
	int ret;

	if (!f)
		return -ENOMEM;

	memset(f, 0, sizeof(*f));
	init_MUTEX_LOCKED(&f->sem);
	f->inocache = ic;

	ret = jffs3_do_read_inode_internal(c, f, &n);
	if (!ret) {
		up(&f->sem);
		jffs3_do_clear_inode(c, f);
	}
	kfree (f);
	return ret;
}

static int jffs3_do_read_inode_internal(struct jffs3_sb_info *c,
					struct jffs3_inode_info *f,
					struct jffs3_raw_inode *latest_node)
{
	struct jffs3_tmp_dnode_info *tn_list, *tn;
	struct jffs3_full_dirent *fd_list;
	struct jffs3_full_dnode *fn = NULL;
	uint32_t crc;
	uint32_t latest_mctime, mctime_ver;
	uint32_t mdata_ver = 0;
	size_t retlen;
	int ret;

	DBG_RI(1, "read ino #%u, nlink %d, state %d\n",
		f->inocache->ino, f->inocache->nlink,
		f->inocache->state);

	/* Grab all nodes relevant to this ino */
	ret = jffs3_get_inode_nodes(c, f, &tn_list, &fd_list, &f->highest_version, &latest_mctime, &mctime_ver);

	if (ret) {
		WARNING_MSG("for ino %u returned %d\n", f->inocache->ino, ret);
		if (f->inocache->state == INO_STATE_READING)
			jffs3_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);
		return ret;
	}
	f->dents = fd_list;

	while (tn_list) {
		tn = tn_list;

		fn = tn->fn;

		if (f->metadata) {
			if (likely(tn->version >= mdata_ver)) {
				DBG_RI(1, "Obsoleting old metadata at 0x%08x\n", ref_offset(f->metadata->raw));
				jffs3_mark_node_obsolete(c, f->metadata->raw);
				jffs3_free_full_dnode(f->metadata);
				f->metadata = NULL;

				mdata_ver = 0;
			} else {
				/* This should never happen. */
				WARNING_MSG("Er. New metadata at 0x%08x with ver %d is actually older "
					"than previous ver %d at 0x%08x\n",
					ref_offset(fn->raw), tn->version, mdata_ver, ref_offset(f->metadata->raw));
				jffs3_mark_node_obsolete(c, fn->raw);
				jffs3_free_full_dnode(fn);
				/* Fill in latest_node from the metadata, not this one we're about to free... */
				fn = f->metadata;
				goto next_tn;
			}
		}

		if (fn->size) {
			jffs3_add_full_dnode_to_inode(c, f, fn);
		} else {
			/* Zero-sized node at end of version list. Just a metadata update */
			DBG_RI(1, "metadata @%08x: ver %d\n", ref_offset(fn->raw), tn->version);
			f->metadata = fn;
			mdata_ver = tn->version;
		}
	next_tn:
		tn_list = tn->next;
		jffs3_free_tmp_dnode_info(tn);
	}

	if (PARANOIA)
		jffs3_dbg_fragtree_paranoia_check(f);

	if (!fn) {
		/* No data nodes for this inode. */
		if (f->inocache->ino != 1) {
			if (!fd_list) {
				WARNING_MSG("No data nodes found for ino #%u\n", f->inocache->ino);
				if (f->inocache->state == INO_STATE_READING)
					jffs3_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);
				return -EIO;
			} else
			DBG_RI(1, "No data nodes found for ino #%u, but it has children "
				"so we fake some modes for it\n", f->inocache->ino);
		}
		latest_node->mode = cpu_to_jemode(S_IFDIR|S_IRUGO|S_IWUSR|S_IXUGO);
		latest_node->version = cpu_to_je32(0);
		latest_node->atime = latest_node->ctime = latest_node->mtime = cpu_to_je32(0);
		latest_node->isize = cpu_to_je32(0);
		latest_node->gid = cpu_to_je16(0);
		latest_node->uid = cpu_to_je16(0);
		if (f->inocache->state == INO_STATE_READING)
			jffs3_set_inocache_state(c, f->inocache, INO_STATE_PRESENT);
		return 0;
	}

	ret = jffs3_flash_read(c, ref_offset(fn->raw), sizeof(*latest_node), &retlen, (void *)latest_node);
	if (ret || retlen != sizeof(*latest_node)) {
		WARNING_MSG("MTD read failed: Returned %d, %zd of %zd bytes read\n",
				ret, retlen, sizeof(*latest_node));
		/* FIXME: If this fails, there seems to be a memory leak. Find it. */
		up(&f->sem);
		jffs3_do_clear_inode(c, f);
		return ret?ret:-EIO;
	}

	crc = crc32(0, latest_node, sizeof(*latest_node)-8);
	if (crc != je32_to_cpu(latest_node->node_crc)) {
		WARNING_MSG("CRC failed for read_inode of inode %u at physical location 0x%x\n",
				f->inocache->ino, ref_offset(fn->raw));
		up(&f->sem);
		jffs3_do_clear_inode(c, f);
		return -EIO;
	}

	switch(jemode_to_cpu(latest_node->mode) & S_IFMT) {
	case S_IFDIR:
		if (mctime_ver > je32_to_cpu(latest_node->version)) {
			/* The times in the latest_node are actually older than
			   mctime in the latest dirent. Cheat. */
			latest_node->ctime = latest_node->mtime = cpu_to_je32(latest_mctime);
		}
		break;


	case S_IFREG:
		/* If it was a regular file, truncate it to the latest node's isize */
		jffs3_truncate_fraglist(c, &f->fragtree, je32_to_cpu(latest_node->isize));
		break;

	case S_IFLNK:
		/* Hack to work around broken isize in old symlink code.
		   Remove this when dwmw2 comes to his senses and stops
		   symlinks from being an entirely gratuitous special
		   case. */
		if (!je32_to_cpu(latest_node->isize))
			latest_node->isize = latest_node->dsize;
		/* fall through... */

	case S_IFBLK:
	case S_IFCHR:
		/* Certain inode types should have only one data node, and it's
		   kept as the metadata node */
		if (f->metadata) {
			WARNING_MSG("Argh. Special inode #%u with mode 0%o had metadata node\n",
			       f->inocache->ino, jemode_to_cpu(latest_node->mode));
			up(&f->sem);
			jffs3_do_clear_inode(c, f);
			return -EIO;
		}
		if (!frag_first(&f->fragtree)) {
			WARNING_MSG("Argh. Special inode #%u with mode 0%o has no fragments\n",
			       f->inocache->ino, jemode_to_cpu(latest_node->mode));
			up(&f->sem);
			jffs3_do_clear_inode(c, f);
			return -EIO;
		}
		/* ASSERT: f->fraglist != NULL */
		if (frag_next(frag_first(&f->fragtree))) {
			WARNING_MSG("Argh. Special inode #%u with mode 0x%x had more than one node\n",
			       f->inocache->ino, jemode_to_cpu(latest_node->mode));
			/* FIXME: Deal with it - check crc32, check for duplicate node, check times and discard the older one */
			up(&f->sem);
			jffs3_do_clear_inode(c, f);
			return -EIO;
		}
		/* OK. We're happy */
		f->metadata = frag_first(&f->fragtree)->node;
		jffs3_free_node_frag(frag_first(&f->fragtree));
		f->fragtree = RB_ROOT;
		break;
	}
	if (f->inocache->state == INO_STATE_READING)
		jffs3_set_inocache_state(c, f->inocache, INO_STATE_PRESENT);

	return 0;
}

void jffs3_do_clear_inode(struct jffs3_sb_info *c, struct jffs3_inode_info *f)
{
	struct jffs3_full_dirent *fd, *fds;
	int deleted;

	down(&f->sem);
	deleted = f->inocache && !f->inocache->nlink;

	if (f->metadata) {
		if (deleted)
			jffs3_mark_node_obsolete(c, f->metadata->raw);
		jffs3_free_full_dnode(f->metadata);
	}

	jffs3_kill_fragtree(&f->fragtree, deleted?c:NULL);

	fds = f->dents;

	while(fds) {
		fd = fds;
		fds = fd->next;
		jffs3_free_full_dirent(fd);
	}

	if (!deleted && f->inocache->state != INO_STATE_CHECKING)
		jffs3_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);

	up(&f->sem);
}