fs/jffs2/readinode.c

/*
 * JFFS2 -- Journalling Flash File System, Version 2.
 *
 * Copyright (C) 2001-2003 Red Hat, Inc.
 *
 * Created by David Woodhouse <dwmw2@infradead.org>
 *
 * For licensing information, see the file 'LICENCE' in this directory.
 *
 * $Id: readinode.c,v 1.134 2005/07/31 08:20:44 dedekind Exp $
 *
 */

#include <linux/kernel.h>
#include <linux/sched.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"

/* 
 * Put a new tmp_dnode_info into the temporaty RB-tree, keeping the list in 
 * order of increasing version.
 */
static void jffs2_add_tn_to_tree(struct jffs2_tmp_dnode_info *tn, struct rb_root *list)
{
	struct rb_node **p = &list->rb_node;
	struct rb_node * parent = NULL;
	struct jffs2_tmp_dnode_info *this;

	while (*p) {
		parent = *p;
		this = rb_entry(parent, struct jffs2_tmp_dnode_info, rb);

		/* There may actually be a collision here, but it doesn't
		   actually matter. As long as the two nodes with the same
		   version are together, it's all fine. */
		if (tn->version < this->version)
			p = &(*p)->rb_left;
		else
			p = &(*p)->rb_right;
        }

	rb_link_node(&tn->rb, parent, p);
	rb_insert_color(&tn->rb, list);
}

static void jffs2_free_tmp_dnode_info_list(struct rb_root *list)
{
	struct rb_node *this;
	struct jffs2_tmp_dnode_info *tn;

	this = list->rb_node;

	/* Now at bottom of tree */
	while (this) {
		if (this->rb_left)
			this = this->rb_left;
		else if (this->rb_right)
			this = this->rb_right;
		else {
			tn = rb_entry(this, struct jffs2_tmp_dnode_info, rb);
			jffs2_free_full_dnode(tn->fn);
			jffs2_free_tmp_dnode_info(tn);

			this = this->rb_parent;
			if (!this)
				break;

			if (this->rb_left == &tn->rb)
				this->rb_left = NULL;
			else if (this->rb_right == &tn->rb)
				this->rb_right = NULL;
			else BUG();
		}
	}
	list->rb_node = NULL;
}

static void jffs2_free_full_dirent_list(struct jffs2_full_dirent *fd)
{
	struct jffs2_full_dirent *next;

	while (fd) {
		next = fd->next;
		jffs2_free_full_dirent(fd);
		fd = next;
	}
}

/* Returns first valid node after 'ref'. May return 'ref' */
static struct jffs2_raw_node_ref *jffs2_first_valid_node(struct jffs2_raw_node_ref *ref)
{
	while (ref && ref->next_in_ino) {
		if (!ref_obsolete(ref))
			return ref;
		JFFS2_DBG_NODEREF("node at 0x%08x is obsoleted. Ignoring.\n", ref_offset(ref));
		ref = ref->next_in_ino;
	}
	return NULL;
}

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an directory entry node is found.
 *
 * Returns: 0 on succes;
 * 	    1 if the node should be marked obsolete;
 * 	    negative error code on failure.
 */
static inline int
read_direntry(struct jffs2_sb_info *c,
	      struct jffs2_raw_node_ref *ref,
	      struct jffs2_raw_dirent *rd,
	      uint32_t read,
	      struct jffs2_full_dirent **fdp,
	      int32_t *latest_mctime,
	      uint32_t *mctime_ver)
{
	struct jffs2_full_dirent *fd;
	
	/* The direntry nodes are checked during the flash scanning */
	BUG_ON(ref_flags(ref) == REF_UNCHECKED);
	/* Obsoleted. This cannot happen, surely? dwmw2 20020308 */
	BUG_ON(ref_obsolete(ref));
			
	/* Sanity check */
	if (unlikely(PAD((rd->nsize + sizeof(*rd))) != PAD(je32_to_cpu(rd->totlen)))) {
		JFFS2_ERROR("illegal nsize in node at %#08x: nsize %#02x, totlen %#04x\n",
		       ref_offset(ref), rd->nsize, je32_to_cpu(rd->totlen));
		return 1;
	}
	
	fd = jffs2_alloc_full_dirent(rd->nsize + 1);
	if (unlikely(!fd))
		return -ENOMEM;

	fd->raw = ref;
	fd->version = je32_to_cpu(rd->version);
	fd->ino = je32_to_cpu(rd->ino);
	fd->type = rd->type;

	/* Pick out the mctime of the latest dirent */
	if(fd->version > *mctime_ver) {
		*mctime_ver = fd->version;
		*latest_mctime = je32_to_cpu(rd->mctime);
	}

	/* 
	 * Copy as much of the name as possible from the raw
	 * dirent we've already read from the flash.
	 */
	if (read > sizeof(*rd))
		memcpy(&fd->name[0], &rd->name[0],
		       min_t(uint32_t, rd->nsize, (read - sizeof(*rd)) ));
		
	/* Do we need to copy any more of the name directly from the flash? */
	if (rd->nsize + sizeof(*rd) > read) {
		/* FIXME: point() */
		int err;
		int already = read - sizeof(*rd);
			
		err = jffs2_flash_read(c, (ref_offset(ref)) + read, 
				rd->nsize - already, &read, &fd->name[already]);
		if (unlikely(read != rd->nsize - already) && likely(!err))
			return -EIO;
			
		if (unlikely(err)) {
			JFFS2_ERROR("read remainder of name: error %d\n", err);
			jffs2_free_full_dirent(fd);
			return -EIO;
		}
	}
	
	fd->nhash = full_name_hash(fd->name, rd->nsize);
	fd->next = NULL;
	fd->name[rd->nsize] = '\0';
	
	/*
	 * Wheee. We now have a complete jffs2_full_dirent structure, with
	 * the name in it and everything. Link it into the list 
	 */
	jffs2_add_fd_to_list(c, fd, fdp);

	return 0;
}

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an inode node is found.
 *
 * Returns: 0 on succes;
 * 	    1 if the node should be marked obsolete;
 * 	    negative error code on failure.
 */
static inline int
read_dnode(struct jffs2_sb_info *c,
	   struct jffs2_raw_node_ref *ref,
	   struct jffs2_raw_inode *rd,
	   uint32_t read,
	   struct rb_root *tnp,
	   int32_t *latest_mctime,
	   uint32_t *mctime_ver)
{
	struct jffs2_eraseblock *jeb;
	struct jffs2_tmp_dnode_info *tn;
	
	/* Obsoleted. This cannot happen, surely? dwmw2 20020308 */
	BUG_ON(ref_obsolete(ref));

	/* If we've never checked the CRCs on this node, check them now */
	if (ref_flags(ref) == REF_UNCHECKED) {
		uint32_t crc, len;

		crc = crc32(0, rd, sizeof(*rd) - 8);
		if (unlikely(crc != je32_to_cpu(rd->node_crc))) {
			JFFS2_NOTICE("header CRC failed on node at %#08x: read %#08x, calculated %#08x\n",
					ref_offset(ref), je32_to_cpu(rd->node_crc), crc);
			return 1;
		}
		
		/* Sanity checks */
		if (unlikely(je32_to_cpu(rd->offset) > je32_to_cpu(rd->isize)) ||
		    unlikely(PAD(je32_to_cpu(rd->csize) + sizeof(*rd)) != PAD(je32_to_cpu(rd->totlen)))) {
				JFFS2_WARNING("inode node header CRC is corrupted at %#08x\n", ref_offset(ref));
				jffs2_dbg_dump_node(c, ref_offset(ref));
			return 1;
		}

		if (rd->compr != JFFS2_COMPR_ZERO && je32_to_cpu(rd->csize)) {
			unsigned char *buf = NULL;
			uint32_t pointed = 0;
			int err;
#ifndef __ECOS
			if (c->mtd->point) {
				err = c->mtd->point (c->mtd, ref_offset(ref) + sizeof(*rd), je32_to_cpu(rd->csize),
						     &read, &buf);
				if (unlikely(read < je32_to_cpu(rd->csize)) && likely(!err)) {
					JFFS2_ERROR("MTD point returned len too short: 0x%zx\n", read);
					c->mtd->unpoint(c->mtd, buf, ref_offset(ref) + sizeof(*rd),
							je32_to_cpu(rd->csize));
				} else if (unlikely(err)){
					JFFS2_ERROR("MTD point failed %d\n", err);
				} else
					pointed = 1; /* succefully pointed to device */
			}
#endif					
			if(!pointed){
				buf = kmalloc(je32_to_cpu(rd->csize), GFP_KERNEL);
				if (!buf)
					return -ENOMEM;
				
				err = jffs2_flash_read(c, ref_offset(ref) + sizeof(*rd), je32_to_cpu(rd->csize),
							&read, buf);
				if (unlikely(read != je32_to_cpu(rd->csize)) && likely(!err))
					err = -EIO;
				if (err) {
					kfree(buf);
					return err;
				}
			}
			crc = crc32(0, buf, je32_to_cpu(rd->csize));
			if(!pointed)
				kfree(buf);
#ifndef __ECOS
			else
				c->mtd->unpoint(c->mtd, buf, ref_offset(ref) + sizeof(*rd), je32_to_cpu(rd->csize));
#endif

			if (crc != je32_to_cpu(rd->data_crc)) {
				JFFS2_NOTICE("data CRC failed on node at %#08x: read %#08x, calculated %#08x\n",
					ref_offset(ref), je32_to_cpu(rd->data_crc), crc);
				return 1;
			}
			
		}

		/* Mark the node as having been checked and fix the accounting accordingly */
		jeb = &c->blocks[ref->flash_offset / c->sector_size];
		len = ref_totlen(c, jeb, ref);

		spin_lock(&c->erase_completion_lock);
		jeb->used_size += len;
		jeb->unchecked_size -= len;
		c->used_size += len;
		c->unchecked_size -= len;

		/* If node covers at least a whole page, or if it starts at the 
		   beginning of a page and runs to the end of the file, or if 
		   it's a hole node, mark it REF_PRISTINE, else REF_NORMAL. 

		   If it's actually overlapped, it'll get made NORMAL (or OBSOLETE) 
		   when the overlapping node(s) get added to the tree anyway. 
		*/
		if ((je32_to_cpu(rd->dsize) >= PAGE_CACHE_SIZE) ||
		    ( ((je32_to_cpu(rd->offset) & (PAGE_CACHE_SIZE-1))==0) &&
		      (je32_to_cpu(rd->dsize) + je32_to_cpu(rd->offset) == je32_to_cpu(rd->isize)))) {
			JFFS2_DBG_READINODE("marking node at %#08x REF_PRISTINE\n", ref_offset(ref));
			ref->flash_offset = ref_offset(ref) | REF_PRISTINE;
		} else {
			JFFS2_DBG_READINODE("marking node at %#08x REF_NORMAL\n", ref_offset(ref));
			ref->flash_offset = ref_offset(ref) | REF_NORMAL;
		}
		spin_unlock(&c->erase_completion_lock);
	}

	tn = jffs2_alloc_tmp_dnode_info();
	if (!tn) {
		JFFS2_ERROR("alloc tn failed\n");
		return -ENOMEM;
	}

	tn->fn = jffs2_alloc_full_dnode();
	if (!tn->fn) {
		JFFS2_ERROR("alloc fn failed\n");
		jffs2_free_tmp_dnode_info(tn);
		return -ENOMEM;
	}
	
	tn->version = je32_to_cpu(rd->version);
	tn->fn->ofs = je32_to_cpu(rd->offset);
	tn->fn->raw = ref;
	
	/* There was a bug where we wrote hole nodes out with
	   csize/dsize swapped. Deal with it */
	if (rd->compr == JFFS2_COMPR_ZERO && !je32_to_cpu(rd->dsize) && je32_to_cpu(rd->csize))
		tn->fn->size = je32_to_cpu(rd->csize);
	else // normal case...
		tn->fn->size = je32_to_cpu(rd->dsize);

	JFFS2_DBG_READINODE("dnode @%08x: ver %u, offset %#04x, dsize %#04x\n",
		  ref_offset(ref), je32_to_cpu(rd->version), je32_to_cpu(rd->offset), je32_to_cpu(rd->dsize));
	
	jffs2_add_tn_to_tree(tn, tnp);

	return 0;
}

/*
 * Helper function for jffs2_get_inode_nodes().
 * It is called every time an unknown node is found.
 *
 * Returns: 0 on succes;
 * 	    1 if the node should be marked obsolete;
 * 	    negative error code on failure.
 */
static inline int
read_unknown(struct jffs2_sb_info *c,
	     struct jffs2_raw_node_ref *ref,
	     struct jffs2_unknown_node *un,
	     uint32_t read)
{
	/* We don't mark unknown nodes as REF_UNCHECKED */
	BUG_ON(ref_flags(ref) == REF_UNCHECKED);
	
	un->nodetype = cpu_to_je16(JFFS2_NODE_ACCURATE | je16_to_cpu(un->nodetype));

	if (crc32(0, un, sizeof(struct jffs2_unknown_node) - 4) != je32_to_cpu(un->hdr_crc)) {
		/* Hmmm. This should have been caught at scan time. */
		JFFS2_NOTICE("node header CRC failed at %#08x. But it must have been OK earlier.\n", ref_offset(ref));
		jffs2_dbg_dump_node(c, ref_offset(ref));
		return 1;
	} else {
		switch(je16_to_cpu(un->nodetype) & JFFS2_COMPAT_MASK) {

		case JFFS2_FEATURE_INCOMPAT:
			JFFS2_ERROR("unknown INCOMPAT nodetype %#04X at %#08x\n",
				je16_to_cpu(un->nodetype), ref_offset(ref));
			/* EEP */
			BUG();
			break;

		case JFFS2_FEATURE_ROCOMPAT:
			JFFS2_ERROR("unknown ROCOMPAT nodetype %#04X at %#08x\n",
					je16_to_cpu(un->nodetype), ref_offset(ref));
			BUG_ON(!(c->flags & JFFS2_SB_FLAG_RO));
			break;

		case JFFS2_FEATURE_RWCOMPAT_COPY:
			JFFS2_NOTICE("unknown RWCOMPAT_COPY nodetype %#04X at %#08x\n",
					je16_to_cpu(un->nodetype), ref_offset(ref));
			break;

		case JFFS2_FEATURE_RWCOMPAT_DELETE:
			JFFS2_NOTICE("unknown RWCOMPAT_DELETE nodetype %#04X at %#08x\n",
					je16_to_cpu(un->nodetype), ref_offset(ref));
			return 1;
		}
	}

	return 0;
}

/* Get tmp_dnode_info and full_dirent for all non-obsolete nodes associated
   with this ino, returning the former in order of version */

static int jffs2_get_inode_nodes(struct jffs2_sb_info *c, struct jffs2_inode_info *f,
				 struct rb_root *tnp, struct jffs2_full_dirent **fdp,
				 uint32_t *highest_version, uint32_t *latest_mctime,
				 uint32_t *mctime_ver)
{
	struct jffs2_raw_node_ref *ref, *valid_ref;
	struct rb_root ret_tn = RB_ROOT;
	struct jffs2_full_dirent *ret_fd = NULL;
	union jffs2_node_union node;
	size_t retlen;
	int err;

	*mctime_ver = 0;
	
	JFFS2_DBG_READINODE("ino #%u\n", f->inocache->ino);

	spin_lock(&c->erase_completion_lock);

	valid_ref = jffs2_first_valid_node(f->inocache->nodes);

	if (!valid_ref && (f->inocache->ino != 1))
		JFFS2_WARNING("no valid nodes for ino #%u\n", f->inocache->ino);

	while (valid_ref) {
		/* We can hold a pointer to a non-obsolete node without the spinlock,
		   but _obsolete_ nodes may disappear at any time, if the block
		   they're in gets erased. So if we mark 'ref' obsolete while we're
		   not holding the lock, it can go away immediately. For that reason,
		   we find the next valid node first, before processing 'ref'.
		*/
		ref = valid_ref;
		valid_ref = jffs2_first_valid_node(ref->next_in_ino);
		spin_unlock(&c->erase_completion_lock);

		cond_resched();

		/* FIXME: point() */
		err = jffs2_flash_read(c, (ref_offset(ref)), 
				       min_t(uint32_t, ref_totlen(c, NULL, ref), sizeof(node)),
				       &retlen, (void *)&node);
		if (err) {
			JFFS2_ERROR("error %d reading node at 0x%08x in get_inode_nodes()\n", err, ref_offset(ref));
			goto free_out;
		}
			
		switch (je16_to_cpu(node.u.nodetype)) {
			
		case JFFS2_NODETYPE_DIRENT:
			JFFS2_DBG_READINODE("node at %08x (%d) is a dirent node\n", ref_offset(ref), ref_flags(ref));
			
			if (retlen < sizeof(node.d)) {
				JFFS2_ERROR("short read dirent at %#08x\n", ref_offset(ref));
				err = -EIO;
				goto free_out;
			}

			err = read_direntry(c, ref, &node.d, retlen, &ret_fd, latest_mctime, mctime_ver);
			if (err == 1) {
				jffs2_mark_node_obsolete(c, ref);
				break;
			} else if (unlikely(err))
				goto free_out;
			
			if (je32_to_cpu(node.d.version) > *highest_version)
				*highest_version = je32_to_cpu(node.d.version);

			break;

		case JFFS2_NODETYPE_INODE:
			JFFS2_DBG_READINODE("node at %08x (%d) is a data node\n", ref_offset(ref), ref_flags(ref));
			
			if (retlen < sizeof(node.i)) {
				JFFS2_ERROR("short read dnode at %#08x\n", ref_offset(ref));
				err = -EIO;
				goto free_out;
			}

			err = read_dnode(c, ref, &node.i, retlen, &ret_tn, latest_mctime, mctime_ver);
			if (err == 1) {
				jffs2_mark_node_obsolete(c, ref);
				break;
			} else if (unlikely(err))
				goto free_out;

			if (je32_to_cpu(node.i.version) > *highest_version)
				*highest_version = je32_to_cpu(node.i.version);
			
			JFFS2_DBG_READINODE("version %d, highest_version now %d\n",
					je32_to_cpu(node.i.version), *highest_version);

			break;

		default:
			/* Check we've managed to read at least the common node header */
			if (retlen < sizeof(struct jffs2_unknown_node)) {
				JFFS2_ERROR("short read unknown node at %#08x\n", ref_offset(ref));
				return -EIO;
			}

			err = read_unknown(c, ref, &node.u, retlen);
			if (err == 1) {
				jffs2_mark_node_obsolete(c, ref);
				break;
			} else if (unlikely(err))
				goto free_out;

		}
		spin_lock(&c->erase_completion_lock);

	}
	spin_unlock(&c->erase_completion_lock);
	*tnp = ret_tn;
	*fdp = ret_fd;

	return 0;

 free_out:
	jffs2_free_tmp_dnode_info_list(&ret_tn);
	jffs2_free_full_dirent_list(ret_fd);
	return err;
}

static int jffs2_do_read_inode_internal(struct jffs2_sb_info *c, 
					struct jffs2_inode_info *f,
					struct jffs2_raw_inode *latest_node)
{
	struct jffs2_tmp_dnode_info *tn = NULL;
	struct rb_root tn_list;
	struct rb_node *rb, *repl_rb;
	struct jffs2_full_dirent *fd_list;
	struct jffs2_full_dnode *fn = NULL;
	uint32_t crc;
	uint32_t latest_mctime, mctime_ver;
	uint32_t mdata_ver = 0;
	size_t retlen;
	int ret;

	JFFS2_DBG_READINODE("ino #%u nlink is %d\n", f->inocache->ino, f->inocache->nlink);

	/* Grab all nodes relevant to this ino */
	ret = jffs2_get_inode_nodes(c, f, &tn_list, &fd_list, &f->highest_version, &latest_mctime, &mctime_ver);

	if (ret) {
		JFFS2_ERROR("cannot read nodes for ino %u, returned error is %d\n", f->inocache->ino, ret);
		if (f->inocache->state == INO_STATE_READING)
			jffs2_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);
		return ret;
	}
	f->dents = fd_list;

	rb = rb_first(&tn_list);

	while (rb) {
		tn = rb_entry(rb, struct jffs2_tmp_dnode_info, rb);
		fn = tn->fn;

		if (f->metadata) {
			if (likely(tn->version >= mdata_ver)) {
				JFFS2_DBG_READINODE("obsoleting old metadata at 0x%08x\n", ref_offset(f->metadata->raw));
				jffs2_mark_node_obsolete(c, f->metadata->raw);
				jffs2_free_full_dnode(f->metadata);
				f->metadata = NULL;
				
				mdata_ver = 0;
			} else {
				/* This should never happen. */
				JFFS2_ERROR("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));
				jffs2_mark_node_obsolete(c, fn->raw);
				jffs2_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) {
			jffs2_add_full_dnode_to_inode(c, f, fn);
		} else {
			/* Zero-sized node at end of version list. Just a metadata update */
			JFFS2_DBG_READINODE("metadata @%08x: ver %d\n", ref_offset(fn->raw), tn->version);
			f->metadata = fn;
			mdata_ver = tn->version;
		}
	next_tn:
		BUG_ON(rb->rb_left);
		if (rb->rb_parent && rb->rb_parent->rb_left == rb) {
			/* We were then left-hand child of our parent. We need
			   to move our own right-hand child into our place. */
			repl_rb = rb->rb_right;
			if (repl_rb)
				repl_rb->rb_parent = rb->rb_parent;
		} else
			repl_rb = NULL;

		rb = rb_next(rb);

		/* Remove the spent tn from the tree; don't bother rebalancing
		   but put our right-hand child in our own place. */
		if (tn->rb.rb_parent) {
			if (tn->rb.rb_parent->rb_left == &tn->rb)
				tn->rb.rb_parent->rb_left = repl_rb;
			else if (tn->rb.rb_parent->rb_right == &tn->rb)
				tn->rb.rb_parent->rb_right = repl_rb;
			else BUG();
		} else if (tn->rb.rb_right)
			tn->rb.rb_right->rb_parent = NULL;

		jffs2_free_tmp_dnode_info(tn);
	}
	jffs2_dbg_fragtree_paranoia_check_nolock(f);

	if (!fn) {
		/* No data nodes for this inode. */
		if (f->inocache->ino != 1) {
			JFFS2_WARNING("no data nodes found for ino #%u\n", f->inocache->ino);
			if (!fd_list) {
				if (f->inocache->state == INO_STATE_READING)
					jffs2_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);
				return -EIO;
			}
			JFFS2_NOTICE("but it has children so we fake some modes for it\n");
		}
		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)
			jffs2_set_inocache_state(c, f->inocache, INO_STATE_PRESENT);
		return 0;
	}

	ret = jffs2_flash_read(c, ref_offset(fn->raw), sizeof(*latest_node), &retlen, (void *)latest_node);
	if (ret || retlen != sizeof(*latest_node)) {
		JFFS2_ERROR("failed to read from flash: error %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);
		jffs2_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)) {
		JFFS2_ERROR("CRC failed for read_inode of inode %u at physical location 0x%x\n",
			f->inocache->ino, ref_offset(fn->raw));
		up(&f->sem);
		jffs2_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 */
		jffs2_truncate_fragtree(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;

		if (f->inocache->state != INO_STATE_CHECKING) {
			/* Symlink's inode data is the target path. Read it and
			 * keep in RAM to facilitate quick follow symlink
			 * operation. */
			f->target = kmalloc(je32_to_cpu(latest_node->csize) + 1, GFP_KERNEL);
			if (!f->target) {
				JFFS2_ERROR("can't allocate %d bytes of memory for the symlink target path cache\n", je32_to_cpu(latest_node->csize));
				up(&f->sem);
				jffs2_do_clear_inode(c, f);
				return -ENOMEM;
			}
			
			ret = jffs2_flash_read(c, ref_offset(fn->raw) + sizeof(*latest_node),
						je32_to_cpu(latest_node->csize), &retlen, (char *)f->target);
			
			if (ret  || retlen != je32_to_cpu(latest_node->csize)) {
				if (retlen != je32_to_cpu(latest_node->csize))
					ret = -EIO;
				kfree(f->target);
				f->target = NULL;
				up(&f->sem);
				jffs2_do_clear_inode(c, f);
				return -ret;
			}

			f->target[je32_to_cpu(latest_node->csize)] = '\0';
			JFFS2_DBG_READINODE("symlink's target '%s' cached\n", f->target);
		}
		
		/* 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) {
			JFFS2_ERROR("Argh. Special inode #%u with mode 0%o had metadata node\n",
			       f->inocache->ino, jemode_to_cpu(latest_node->mode));
			up(&f->sem);
			jffs2_do_clear_inode(c, f);
			return -EIO;
		}
		if (!frag_first(&f->fragtree)) {
			JFFS2_ERROR("Argh. Special inode #%u with mode 0%o has no fragments\n",
			       f->inocache->ino, jemode_to_cpu(latest_node->mode));
			up(&f->sem);
			jffs2_do_clear_inode(c, f);
			return -EIO;
		}
		/* ASSERT: f->fraglist != NULL */
		if (frag_next(frag_first(&f->fragtree))) {
			JFFS2_ERROR("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);
			jffs2_do_clear_inode(c, f);
			return -EIO;
		}
		/* OK. We're happy */
		f->metadata = frag_first(&f->fragtree)->node;
		jffs2_free_node_frag(frag_first(&f->fragtree));
		f->fragtree = RB_ROOT;
		break;
	}
	if (f->inocache->state == INO_STATE_READING)
		jffs2_set_inocache_state(c, f->inocache, INO_STATE_PRESENT);

	return 0;
}

/* Scan the list of all nodes present for this ino, build map of versions, etc. */
int jffs2_do_read_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f, 
			uint32_t ino, struct jffs2_raw_inode *latest_node)
{
	JFFS2_DBG_READINODE("read inode #%u\n", ino);

 retry_inocache:
	spin_lock(&c->inocache_lock);
	f->inocache = jffs2_get_ino_cache(c, ino);

	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. */
			JFFS2_DBG_READINODE("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. */
			JFFS2_ERROR("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 = jffs2_alloc_inode_cache();
		if (!f->inocache) {
			JFFS2_ERROR("cannot allocate inocache for root inode\n");
			return -ENOMEM;
		}
		JFFS2_DBG_READINODE("creating inocache for root inode\n");
		memset(f->inocache, 0, sizeof(struct jffs2_inode_cache));
		f->inocache->ino = f->inocache->nlink = 1;
		f->inocache->nodes = (struct jffs2_raw_node_ref *)f->inocache;
		f->inocache->state = INO_STATE_READING;
		jffs2_add_ino_cache(c, f->inocache);
	}
	if (!f->inocache) {
		JFFS2_ERROR("requestied to read an nonexistent ino %u\n", ino);
		return -ENOENT;
	}

	return jffs2_do_read_inode_internal(c, f, latest_node);
}

int jffs2_do_crccheck_inode(struct jffs2_sb_info *c, struct jffs2_inode_cache *ic)
{
	struct jffs2_raw_inode n;
	struct jffs2_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 = jffs2_do_read_inode_internal(c, f, &n);
	if (!ret) {
		up(&f->sem);
		jffs2_do_clear_inode(c, f);
	}
	kfree (f);
	return ret;
}

void jffs2_do_clear_inode(struct jffs2_sb_info *c, struct jffs2_inode_info *f)
{
	struct jffs2_full_dirent *fd, *fds;
	int deleted;

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

	if (f->inocache && f->inocache->state != INO_STATE_CHECKING)
		jffs2_set_inocache_state(c, f->inocache, INO_STATE_CLEARING);

	if (f->metadata) {
		if (deleted)
			jffs2_mark_node_obsolete(c, f->metadata->raw);
		jffs2_free_full_dnode(f->metadata);
	}

	jffs2_kill_fragtree(&f->fragtree, deleted?c:NULL);

	if (f->target) {
		kfree(f->target);
		f->target = NULL;
	}
	
	fds = f->dents;
	while(fds) {
		fd = fds;
		fds = fd->next;
		jffs2_free_full_dirent(fd);
	}

	if (f->inocache && f->inocache->state != INO_STATE_CHECKING) {
		jffs2_set_inocache_state(c, f->inocache, INO_STATE_CHECKEDABSENT);
		if (f->inocache->nodes == (void *)f->inocache)
			jffs2_del_ino_cache(c, f->inocache);
	}

	up(&f->sem);
}