patch-2.4.10 linux/fs/jffs2/scan.c

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diff -u --recursive --new-file v2.4.9/linux/fs/jffs2/scan.c linux/fs/jffs2/scan.c
@@ -0,0 +1,658 @@
+/*
+ * JFFS2 -- Journalling Flash File System, Version 2.
+ *
+ * Copyright (C) 2001 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: scan.c,v 1.44 2001/04/13 00:46:41 nico Exp $
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/jffs2.h>
+#include <linux/mtd/mtd.h>
+#include <linux/pagemap.h>
+#include "nodelist.h"
+#include "crc32.h"
+
+
+#define DIRTY_SPACE(x) do { typeof(x) _x = (x); \
+		c->free_size -= _x; c->dirty_size += _x; \
+		jeb->free_size -= _x ; jeb->dirty_size += _x; \
+		}while(0)
+#define USED_SPACE(x) do { typeof(x) _x = (x); \
+		c->free_size -= _x; c->used_size += _x; \
+		jeb->free_size -= _x ; jeb->used_size += _x; \
+		}while(0)
+
+#define noisy_printk(noise, args...) do { \
+	if (*(noise)) { \
+		printk(KERN_NOTICE args); \
+		 (*(noise))--; \
+		 if (!(*(noise))) { \
+			 printk(KERN_NOTICE "Further such events for this erase block will not be printed\n"); \
+		 } \
+	} \
+} while(0)
+
+static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb);
+
+/* These helper functions _must_ increase ofs and also do the dirty/used space accounting. 
+ * Returning an error will abort the mount - bad checksums etc. should just mark the space
+ * as dirty.
+ */
+static int jffs2_scan_empty(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *ofs, int *noise);
+static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *ofs);
+static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *ofs);
+
+
+int jffs2_scan_medium(struct jffs2_sb_info *c)
+{
+	int i, ret;
+	if (!c->blocks) {
+		printk(KERN_WARNING "EEEK! c->blocks is NULL!\n");
+		return -EINVAL;
+	}
+	for (i=0; i<c->nr_blocks; i++) {
+		struct jffs2_eraseblock *jeb = &c->blocks[i];
+
+		ret = jffs2_scan_eraseblock(c, jeb);
+		if (ret)
+			return ret;
+
+		ACCT_PARANOIA_CHECK(jeb);
+
+		   /* Now decide which list to put it on */
+		if (jeb->used_size == PAD(sizeof(struct jffs2_unknown_node)) && !jeb->first_node->next_in_ino) {
+			/* Only a CLEANMARKER node is valid */
+			if (!jeb->dirty_size) {
+				/* It's actually free */
+				list_add(&jeb->list, &c->free_list);
+				c->nr_free_blocks++;
+			} else {
+				/* Dirt */
+				D1(printk(KERN_DEBUG "Adding all-dirty block at 0x%08x to erase_pending_list\n", jeb->offset));
+				list_add(&jeb->list, &c->erase_pending_list);
+				c->nr_erasing_blocks++;
+			}
+		} else if (jeb->used_size > c->sector_size - (2*sizeof(struct jffs2_raw_inode))) {
+                        /* Full (or almost full) of clean data. Clean list */
+                        list_add(&jeb->list, &c->clean_list);
+                } else if (jeb->used_size) {
+                        /* Some data, but not full. Dirty list. */
+                        /* Except that we want to remember the block with most free space,
+                           and stick it in the 'nextblock' position to start writing to it.
+                           Later when we do snapshots, this must be the most recent block,
+                           not the one with most free space.
+                        */
+                        if (jeb->free_size > 2*sizeof(struct jffs2_raw_inode) && 
+                                (!c->nextblock || c->nextblock->free_size < jeb->free_size)) {
+                                /* Better candidate for the next writes to go to */
+                                if (c->nextblock)
+                                        list_add(&c->nextblock->list, &c->dirty_list);
+                                c->nextblock = jeb;
+                        } else {
+                                list_add(&jeb->list, &c->dirty_list);
+                        }
+		} else {
+			/* Nothing valid - not even a clean marker. Needs erasing. */
+                        /* For now we just put it on the erasing list. We'll start the erases later */
+			printk(KERN_NOTICE "JFFS2: Erase block at 0x%08x is not formatted. It will be erased\n", jeb->offset);
+                        list_add(&jeb->list, &c->erase_pending_list);
+			c->nr_erasing_blocks++;
+                }
+        }
+	if (c->nr_erasing_blocks)
+		jffs2_erase_pending_trigger(c);
+
+	return 0;
+}
+
+static int jffs2_scan_eraseblock (struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb) {
+	struct jffs2_unknown_node node;
+	__u32 ofs, prevofs;
+	__u32 hdr_crc, nodetype;
+	int err;
+	int noise = 10;
+
+	ofs = jeb->offset;
+	prevofs = jeb->offset - 1;
+
+	D1(printk(KERN_DEBUG "jffs2_scan_eraseblock(): Scanning block at 0x%x\n", ofs));
+
+	while(ofs < jeb->offset + c->sector_size) {
+		ssize_t retlen;
+		ACCT_PARANOIA_CHECK(jeb);
+		
+		if (ofs & 3) {
+			printk(KERN_WARNING "Eep. ofs 0x%08x not word-aligned!\n", ofs);
+			ofs = (ofs+3)&~3;
+			continue;
+		}
+		if (ofs == prevofs) {
+			printk(KERN_WARNING "ofs 0x%08x has already been seen. Skipping\n", ofs);
+			DIRTY_SPACE(4);
+			ofs += 4;
+			continue;
+		}
+		prevofs = ofs;
+		
+		if (jeb->offset + c->sector_size < ofs + sizeof(node)) {
+			D1(printk(KERN_DEBUG "Fewer than %d bytes left to end of block. Not reading\n", sizeof(struct jffs2_unknown_node)));
+			DIRTY_SPACE((jeb->offset + c->sector_size)-ofs);
+			break;
+		}
+
+		err = c->mtd->read(c->mtd, ofs, sizeof(node), &retlen, (char *)&node);
+		
+		if (err) {
+			D1(printk(KERN_WARNING "mtd->read(0x%x bytes from 0x%x) returned %d\n", sizeof(node), ofs, err));
+			return err;
+		}
+		if (retlen < sizeof(node)) {
+			D1(printk(KERN_WARNING "Read at 0x%x gave only 0x%x bytes\n", ofs, retlen));
+			DIRTY_SPACE(retlen);
+			ofs += retlen;
+			continue;
+		}
+
+		if (node.magic == JFFS2_EMPTY_BITMASK && node.nodetype == JFFS2_EMPTY_BITMASK) {
+			D1(printk(KERN_DEBUG "Found empty flash at 0x%x\n", ofs));
+			err = jffs2_scan_empty(c, jeb, &ofs, &noise);
+			if (err) return err;
+			continue;
+		}
+
+		if (ofs == jeb->offset && node.magic == KSAMTIB_CIGAM_2SFFJ) {
+			printk(KERN_WARNING "Magic bitmask is backwards at offset 0x%08x. Wrong endian filesystem?\n", ofs);
+			DIRTY_SPACE(4);
+			ofs += 4;
+			continue;
+		}
+		if (node.magic == JFFS2_DIRTY_BITMASK) {
+			D1(printk(KERN_DEBUG "Empty bitmask at 0x%08x\n", ofs));
+			DIRTY_SPACE(4);
+			ofs += 4;
+			continue;
+		}
+		if (node.magic == JFFS2_OLD_MAGIC_BITMASK) {
+			printk(KERN_WARNING "Old JFFS2 bitmask found at 0x%08x\n", ofs);
+			printk(KERN_WARNING "You cannot use older JFFS2 filesystems with newer kernels\n");
+			DIRTY_SPACE(4);
+			ofs += 4;
+			continue;
+		}
+		if (node.magic != JFFS2_MAGIC_BITMASK) {
+			/* OK. We're out of possibilities. Whinge and move on */
+			noisy_printk(&noise, "jffs2_scan_eraseblock(): Magic bitmask 0x%04x not found at 0x%08x: 0x%04x instead\n", JFFS2_MAGIC_BITMASK, ofs, node.magic);
+			DIRTY_SPACE(4);
+			ofs += 4;
+			continue;
+		}
+		/* We seem to have a node of sorts. Check the CRC */
+		nodetype = node.nodetype;
+		node.nodetype |= JFFS2_NODE_ACCURATE;
+		hdr_crc = crc32(0, &node, sizeof(node)-4);
+		node.nodetype = nodetype;
+		if (hdr_crc != node.hdr_crc) {
+			noisy_printk(&noise, "jffs2_scan_eraseblock(): Node at 0x%08x {0x%04x, 0x%04x, 0x%08x) has invalid CRC 0x%08x (calculated 0x%08x)\n",
+				     ofs, node.magic, node.nodetype, node.totlen, node.hdr_crc, hdr_crc);
+			DIRTY_SPACE(4);
+			ofs += 4;
+			continue;
+		}
+
+		switch(node.nodetype | JFFS2_NODE_ACCURATE) {
+		case JFFS2_NODETYPE_INODE:
+			err = jffs2_scan_inode_node(c, jeb, &ofs);
+			if (err) return err;
+			break;
+			
+		case JFFS2_NODETYPE_DIRENT:
+			err = jffs2_scan_dirent_node(c, jeb, &ofs);
+			if (err) return err;
+			break;
+
+		case JFFS2_NODETYPE_CLEANMARKER:
+			if (node.totlen != sizeof(struct jffs2_unknown_node)) {
+				printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x has totlen 0x%x != normal 0x%x\n", 
+				       ofs, node.totlen, sizeof(struct jffs2_unknown_node));
+				DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
+			} else if (jeb->first_node) {
+				printk(KERN_NOTICE "CLEANMARKER node found at 0x%08x, not first node in block (0x%08x)\n", ofs, jeb->offset);
+				DIRTY_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
+				ofs += PAD(sizeof(struct jffs2_unknown_node));
+				continue;
+			} else {
+				struct jffs2_raw_node_ref *marker_ref = jffs2_alloc_raw_node_ref();
+				if (!marker_ref) {
+					printk(KERN_NOTICE "Failed to allocate node ref for clean marker\n");
+					return -ENOMEM;
+				}
+				marker_ref->next_in_ino = NULL;
+				marker_ref->next_phys = NULL;
+				marker_ref->flash_offset = ofs;
+				marker_ref->totlen = sizeof(struct jffs2_unknown_node);
+				jeb->first_node = jeb->last_node = marker_ref;
+			     
+				USED_SPACE(PAD(sizeof(struct jffs2_unknown_node)));
+			}
+			ofs += PAD(sizeof(struct jffs2_unknown_node));
+			break;
+
+		default:
+			switch (node.nodetype & JFFS2_COMPAT_MASK) {
+			case JFFS2_FEATURE_ROCOMPAT:
+				printk(KERN_NOTICE "Read-only compatible feature node (0x%04x) found at offset 0x%08x\n", node.nodetype, ofs);
+			        c->flags |= JFFS2_SB_FLAG_RO;
+				DIRTY_SPACE(PAD(node.totlen));
+				ofs += PAD(node.totlen);
+				continue;
+
+			case JFFS2_FEATURE_INCOMPAT:
+				printk(KERN_NOTICE "Incompatible feature node (0x%04x) found at offset 0x%08x\n", node.nodetype, ofs);
+				return -EINVAL;
+
+			case JFFS2_FEATURE_RWCOMPAT_DELETE:
+				printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", node.nodetype, ofs);
+				DIRTY_SPACE(PAD(node.totlen));
+				ofs += PAD(node.totlen);
+				break;
+
+			case JFFS2_FEATURE_RWCOMPAT_COPY:
+				printk(KERN_NOTICE "Unknown but compatible feature node (0x%04x) found at offset 0x%08x\n", node.nodetype, ofs);
+				USED_SPACE(PAD(node.totlen));
+				ofs += PAD(node.totlen);
+				break;
+			}
+		}
+	}
+	D1(printk(KERN_DEBUG "Block at 0x%08x: free 0x%08x, dirty 0x%08x, used 0x%08x\n", jeb->offset, 
+		  jeb->free_size, jeb->dirty_size, jeb->used_size));
+	return 0;
+}
+
+/* We're pointing at the first empty word on the flash. Scan and account for the whole dirty region */
+static int jffs2_scan_empty(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *startofs, int *noise)
+{
+	__u32 *buf;
+	__u32 scanlen = (jeb->offset + c->sector_size) - *startofs;
+	__u32 curofs = *startofs;
+	
+	buf = kmalloc(min(PAGE_SIZE, scanlen), GFP_KERNEL);
+	if (!buf) {
+		printk(KERN_WARNING "Scan buffer allocation failed\n");
+		return -ENOMEM;
+	}
+	while(scanlen) {
+		ssize_t retlen;
+		int ret, i;
+		
+		ret = c->mtd->read(c->mtd, curofs, min(PAGE_SIZE, scanlen), &retlen, (char *)buf);
+		if(ret) {
+			D1(printk(KERN_WARNING "jffs2_scan_empty(): Read 0x%lx bytes at 0x%08x returned %d\n", min(PAGE_SIZE, scanlen), curofs, ret));
+			kfree(buf);
+			return ret;
+		}
+		if (retlen < 4) {
+			D1(printk(KERN_WARNING "Eep. too few bytes read in scan_empty()\n"));
+			kfree(buf);
+			return -EIO;
+		}
+		for (i=0; i<(retlen / 4); i++) {
+			if (buf[i] != 0xffffffff) {
+				curofs += i*4;
+
+				noisy_printk(noise, "jffs2_scan_empty(): Empty block at 0x%08x ends at 0x%08x (with 0x%08x)! Marking dirty\n", *startofs, curofs, buf[i]);
+				DIRTY_SPACE(curofs - (*startofs));
+				*startofs = curofs;
+				kfree(buf);
+				return 0;
+			}
+		}
+		scanlen -= retlen&~3;
+		curofs += retlen&~3;
+	}
+
+	D1(printk(KERN_DEBUG "Empty flash detected from 0x%08x to 0x%08x\n", *startofs, curofs));
+	kfree(buf);
+	*startofs = curofs;
+	return 0;
+}
+
+static struct jffs2_inode_cache *jffs2_scan_make_ino_cache(struct jffs2_sb_info *c, __u32 ino)
+{
+	struct jffs2_inode_cache *ic;
+
+	ic = jffs2_get_ino_cache(c, ino);
+	if (ic)
+		return ic;
+
+	ic = jffs2_alloc_inode_cache();
+	if (!ic) {
+		printk(KERN_NOTICE "jffs2_scan_make_inode_cache(): allocation of inode cache failed\n");
+		return NULL;
+	}
+	memset(ic, 0, sizeof(*ic));
+	ic->scan = kmalloc(sizeof(struct jffs2_scan_info), GFP_KERNEL);
+	if (!ic->scan) {
+		printk(KERN_NOTICE "jffs2_scan_make_inode_cache(): allocation of scan info for inode cache failed\n");
+		jffs2_free_inode_cache(ic);
+		return NULL;
+	}
+	memset(ic->scan, 0, sizeof(*ic->scan));
+	ic->ino = ino;
+	ic->nodes = (void *)ic;
+	jffs2_add_ino_cache(c, ic);
+	if (ino == 1)
+		ic->nlink=1;
+	return ic;
+}
+
+static int jffs2_scan_inode_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *ofs)
+{
+	struct jffs2_raw_node_ref *raw;
+	struct jffs2_full_dnode *fn;
+	struct jffs2_tmp_dnode_info *tn, **tn_list;
+	struct jffs2_inode_cache *ic;
+	struct jffs2_raw_inode ri;
+	__u32 crc;
+	__u16 oldnodetype;
+	int ret;
+	ssize_t retlen;
+
+	D1(printk(KERN_DEBUG "jffs2_scan_inode_node(): Node at 0x%08x\n", *ofs));
+
+	ret = c->mtd->read(c->mtd, *ofs, sizeof(ri), &retlen, (char *)&ri);
+	if (ret) {
+		printk(KERN_NOTICE "jffs2_scan_inode_node(): Read error at 0x%08x: %d\n", *ofs, ret);
+		return ret;
+	}
+	if (retlen != sizeof(ri)) {
+		printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
+		       retlen, *ofs, sizeof(ri));
+		return -EIO;
+	}
+
+	/* We sort of assume that the node was accurate when it was 
+	   first written to the medium :) */
+	oldnodetype = ri.nodetype;
+	ri.nodetype |= JFFS2_NODE_ACCURATE;
+	crc = crc32(0, &ri, sizeof(ri)-8);
+	ri.nodetype = oldnodetype;
+
+	if(crc != ri.node_crc) {
+		printk(KERN_NOTICE "jffs2_scan_inode_node(): CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+		       *ofs, ri.node_crc, crc);
+		/* FIXME: Why do we believe totlen? */
+		DIRTY_SPACE(4);
+		*ofs += 4;
+		return 0;
+	}
+
+	if (ri.csize) {
+		/* Check data CRC too */
+		unsigned char *dbuf;
+		__u32 crc;
+
+		dbuf = kmalloc(PAGE_CACHE_SIZE, GFP_KERNEL);
+		if (!dbuf) {
+			printk(KERN_NOTICE "jffs2_scan_inode_node(): allocation of temporary data buffer for CRC check failed\n");
+			return -ENOMEM;
+		}
+		ret = c->mtd->read(c->mtd, *ofs+sizeof(ri), ri.csize, &retlen, dbuf);
+		if (ret) {
+			printk(KERN_NOTICE "jffs2_scan_inode_node(): Read error at 0x%08x: %d\n", *ofs+sizeof(ri), ret);
+			kfree(dbuf);
+			return ret;
+		}
+		if (retlen != ri.csize) {
+			printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
+			       retlen, *ofs+ sizeof(ri), ri.csize);
+			kfree(dbuf);
+			return -EIO;
+		}
+		crc = crc32(0, dbuf, ri.csize);
+		kfree(dbuf);
+		if (crc != ri.data_crc) {
+			printk(KERN_NOTICE "jffs2_scan_inode_node(): Data CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+			       *ofs, ri.data_crc, crc);
+			DIRTY_SPACE(PAD(ri.totlen));
+			*ofs += PAD(ri.totlen);
+			return -0;
+		}
+	}
+
+	/* Wheee. It worked */
+	raw = jffs2_alloc_raw_node_ref();
+	if (!raw) {
+		printk(KERN_NOTICE "jffs2_scan_inode_node(): allocation of node reference failed\n");
+		return -ENOMEM;
+	}
+	tn = jffs2_alloc_tmp_dnode_info();
+	if (!tn) {
+		jffs2_free_raw_node_ref(raw);
+		return -ENOMEM;
+	}
+	fn = jffs2_alloc_full_dnode();
+	if (!fn) {
+		jffs2_free_tmp_dnode_info(tn);
+		jffs2_free_raw_node_ref(raw);
+		return -ENOMEM;
+	}
+	ic = jffs2_scan_make_ino_cache(c, ri.ino);
+	if (!ic) {
+		jffs2_free_full_dnode(fn);
+		jffs2_free_tmp_dnode_info(tn);
+		jffs2_free_raw_node_ref(raw);
+		return -ENOMEM;
+	}
+
+	/* Build the data structures and file them for later */
+	raw->flash_offset = *ofs;
+	raw->totlen = PAD(ri.totlen);
+	raw->next_phys = NULL;
+	raw->next_in_ino = ic->nodes;
+	ic->nodes = raw;
+	if (!jeb->first_node)
+		jeb->first_node = raw;
+	if (jeb->last_node)
+		jeb->last_node->next_phys = raw;
+	jeb->last_node = raw;
+
+	D1(printk(KERN_DEBUG "Node is ino #%u, version %d. Range 0x%x-0x%x\n", 
+		  ri.ino, ri.version, ri.offset, ri.offset+ri.dsize));
+
+	for (tn_list = &ic->scan->tmpnodes; *tn_list; tn_list = &((*tn_list)->next)) {
+		if ((*tn_list)->version < ri.version)
+			continue;
+		if ((*tn_list)->version > ri.version) 
+			break;
+		/* Wheee. We've found another instance of the same version number.
+		   We should obsolete one of them. 
+		*/
+		D1(printk(KERN_DEBUG "Duplicate version %d found in ino #%u. Previous one is at 0x%08x\n", ri.version, ic->ino, (*tn_list)->fn->raw->flash_offset &~3));
+		if (!jeb->used_size) {
+			D1(printk(KERN_DEBUG "No valid nodes yet found in this eraseblock 0x%08x, so obsoleting the new instance at 0x%08x\n", 
+				  jeb->offset, raw->flash_offset & ~3));
+			ri.nodetype &= ~JFFS2_NODE_ACCURATE;
+			/* Perhaps we could also mark it as such on the medium. Maybe later */
+		}
+		break;
+	}
+
+	if (ri.nodetype & JFFS2_NODE_ACCURATE) {
+		memset(fn,0,sizeof(*fn));
+
+		fn->ofs = ri.offset;
+		fn->size = ri.dsize;
+		fn->frags = 0;
+		fn->raw = raw;
+
+		tn->next = NULL;
+		tn->fn = fn;
+		tn->version = ri.version;
+
+		USED_SPACE(PAD(ri.totlen));
+		jffs2_add_tn_to_list(tn, &ic->scan->tmpnodes);
+		/* Make sure the one we just added is the _last_ in the list
+		   with this version number, so the older ones get obsoleted */
+		while (tn->next && tn->next->version == tn->version) {
+
+			D1(printk(KERN_DEBUG "Shifting new node at 0x%08x after other node at 0x%08x for version %d in list\n",
+				  fn->raw->flash_offset&~3, tn->next->fn->raw->flash_offset &~3, ri.version));
+
+			if(tn->fn != fn)
+				BUG();
+			tn->fn = tn->next->fn;
+			tn->next->fn = fn;
+			tn = tn->next;
+		}
+	} else {
+		jffs2_free_full_dnode(fn);
+		jffs2_free_tmp_dnode_info(tn);
+		raw->flash_offset |= 1;
+		DIRTY_SPACE(PAD(ri.totlen));
+	}		
+	*ofs += PAD(ri.totlen);
+	return 0;
+}
+
+static int jffs2_scan_dirent_node(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, __u32 *ofs)
+{
+	struct jffs2_raw_node_ref *raw;
+	struct jffs2_full_dirent *fd;
+	struct jffs2_inode_cache *ic;
+	struct jffs2_raw_dirent rd;
+	__u16 oldnodetype;
+	int ret;
+	__u32 crc;
+	ssize_t retlen;
+
+	D1(printk(KERN_DEBUG "jffs2_scan_dirent_node(): Node at 0x%08x\n", *ofs));
+
+	ret = c->mtd->read(c->mtd, *ofs, sizeof(rd), &retlen, (char *)&rd);
+	if (ret) {
+		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Read error at 0x%08x: %d\n", *ofs, ret);
+		return ret;
+	}
+	if (retlen != sizeof(rd)) {
+		printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
+		       retlen, *ofs, sizeof(rd));
+		return -EIO;
+	}
+
+	/* We sort of assume that the node was accurate when it was 
+	   first written to the medium :) */
+	oldnodetype = rd.nodetype;
+	rd.nodetype |= JFFS2_NODE_ACCURATE;
+	crc = crc32(0, &rd, sizeof(rd)-8);
+	rd.nodetype = oldnodetype;
+
+	if (crc != rd.node_crc) {
+		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Node CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+		       *ofs, rd.node_crc, crc);
+		/* FIXME: Why do we believe totlen? */
+		DIRTY_SPACE(4);
+		*ofs += 4;
+		return 0;
+	}
+
+	fd = jffs2_alloc_full_dirent(rd.nsize+1);
+	if (!fd) {
+		return -ENOMEM;
+}
+	ret = c->mtd->read(c->mtd, *ofs + sizeof(rd), rd.nsize, &retlen, &fd->name[0]);
+	if (ret) {
+		jffs2_free_full_dirent(fd);
+		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Read error at 0x%08x: %d\n", 
+		       *ofs + sizeof(rd), ret);
+		return ret;
+	}
+	if (retlen != rd.nsize) {
+		jffs2_free_full_dirent(fd);
+		printk(KERN_NOTICE "Short read: 0x%x bytes at 0x%08x instead of requested %x\n", 
+		       retlen, *ofs + sizeof(rd), rd.nsize);
+		return -EIO;
+	}
+	crc = crc32(0, fd->name, rd.nsize);
+	if (crc != rd.name_crc) {
+		printk(KERN_NOTICE "jffs2_scan_dirent_node(): Name CRC failed on node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
+		       *ofs, rd.name_crc, crc);	
+		jffs2_free_full_dirent(fd);
+		/* FIXME: Why do we believe totlen? */
+		DIRTY_SPACE(PAD(rd.totlen));
+		*ofs += PAD(rd.totlen);
+		return 0;
+	}
+	raw = jffs2_alloc_raw_node_ref();
+	if (!raw) {
+		jffs2_free_full_dirent(fd);
+		printk(KERN_NOTICE "jffs2_scan_dirent_node(): allocation of node reference failed\n");
+		return -ENOMEM;
+	}
+	ic = jffs2_scan_make_ino_cache(c, rd.pino);
+	if (!ic) {
+		jffs2_free_full_dirent(fd);
+		jffs2_free_raw_node_ref(raw);
+		return -ENOMEM;
+	}
+	
+	raw->totlen = PAD(rd.totlen);
+	raw->flash_offset = *ofs;
+	raw->next_phys = NULL;
+	raw->next_in_ino = ic->nodes;
+	ic->nodes = raw;
+	if (!jeb->first_node)
+		jeb->first_node = raw;
+	if (jeb->last_node)
+		jeb->last_node->next_phys = raw;
+	jeb->last_node = raw;
+
+	if (rd.nodetype & JFFS2_NODE_ACCURATE) {
+		fd->raw = raw;
+		fd->next = NULL;
+		fd->version = rd.version;
+		fd->ino = rd.ino;
+		fd->name[rd.nsize]=0;
+		fd->nhash = full_name_hash(fd->name, rd.nsize);
+		fd->type = rd.type;
+
+		USED_SPACE(PAD(rd.totlen));
+		jffs2_add_fd_to_list(c, fd, &ic->scan->dents);
+	} else {
+		raw->flash_offset |= 1;
+		jffs2_free_full_dirent(fd);
+
+		DIRTY_SPACE(PAD(rd.totlen));
+	} 
+	*ofs += PAD(rd.totlen);
+	return 0;
+}
FUNET's LINUX-ADM group, linux-adm@nic.funet.fi
TCL-scripts by Sam Shen (who was at: slshen@lbl.gov)