gc.c

jffs2源代码基于2。6内核

	}
	if (ref_obsolete(raw)) {
		spin_unlock(&c->erase_completion_lock);
		D1(printk(KERN_DEBUG "node to be GC'd was obsoleted in the meantime.\n"));
		/* They'll call again */
		goto upnout;
	}
	spin_unlock(&c->erase_completion_lock);

	/* OK. Looks safe. And nobody can get us now because we have the semaphore. Move the block */
	if (f->metadata && f->metadata->raw == raw) {
		fn = f->metadata;
		ret = jffs2_garbage_collect_metadata(c, jeb, f, fn);
		goto upnout;
	}

	/* FIXME. Read node and do lookup? */
	for (frag = frag_first(&f->fragtree); frag; frag = frag_next(frag)) {
		if (frag->node && frag->node->raw == raw) {
			fn = frag->node;
			end = frag->ofs + frag->size;
			if (!nrfrags++)
				start = frag->ofs;
			if (nrfrags == frag->node->frags)
				break; /* We've found them all */
		}
	}
	if (fn) {
		if (ref_flags(raw) == REF_PRISTINE) {
			ret = jffs2_garbage_collect_pristine(c, f->inocache, raw);
			if (!ret) {
				/* Urgh. Return it sensibly. */
				frag->node->raw = f->inocache->nodes;
			}	
			if (ret != -EBADFD)
				goto upnout;
		}
		/* We found a datanode. Do the GC */
		if((start >> PAGE_CACHE_SHIFT) < ((end-1) >> PAGE_CACHE_SHIFT)) {
			/* It crosses a page boundary. Therefore, it must be a hole. */
			ret = jffs2_garbage_collect_hole(c, jeb, f, fn, start, end);
		} else {
			/* It could still be a hole. But we GC the page this way anyway */
			ret = jffs2_garbage_collect_dnode(c, jeb, f, fn, start, end);
		}
		goto upnout;
	}
	
	/* Wasn't a dnode. Try dirent */
	for (fd = f->dents; fd; fd=fd->next) {
		if (fd->raw == raw)
			break;
	}

	if (fd && fd->ino) {
		ret = jffs2_garbage_collect_dirent(c, jeb, f, fd);
	} else if (fd) {
		ret = jffs2_garbage_collect_deletion_dirent(c, jeb, f, fd);
	} else {
		printk(KERN_WARNING "Raw node at 0x%08x wasn't in node lists for ino #%u\n",
		       ref_offset(raw), f->inocache->ino);
		if (ref_obsolete(raw)) {
			printk(KERN_WARNING "But it's obsolete so we don't mind too much\n");
		} else {
			ret = -EIO;
		}
	}
 upnout:
	up(&f->sem);

	return ret;
}

static int jffs2_garbage_collect_pristine(struct jffs2_sb_info *c, 
					  struct jffs2_inode_cache *ic,
					  struct jffs2_raw_node_ref *raw)
{
	union jffs2_node_union *node;
	struct jffs2_raw_node_ref *nraw;
	size_t retlen;
	int ret;
	uint32_t phys_ofs, alloclen;
	uint32_t crc, rawlen;
	int retried = 0;

	D1(printk(KERN_DEBUG "Going to GC REF_PRISTINE node at 0x%08x\n", ref_offset(raw)));

	rawlen = ref_totlen(c, c->gcblock, raw);

	/* Ask for a small amount of space (or the totlen if smaller) because we
	   don't want to force wastage of the end of a block if splitting would
	   work. */
	ret = jffs2_reserve_space_gc(c, min_t(uint32_t, sizeof(struct jffs2_raw_inode) + JFFS2_MIN_DATA_LEN, 
					      rawlen), &phys_ofs, &alloclen);
	if (ret)
		return ret;

	if (alloclen < rawlen) {
		/* Doesn't fit untouched. We'll go the old route and split it */
		return -EBADFD;
	}

	node = kmalloc(rawlen, GFP_KERNEL);
	if (!node)
               return -ENOMEM;

	ret = jffs2_flash_read(c, ref_offset(raw), rawlen, &retlen, (char *)node);
	if (!ret && retlen != rawlen)
		ret = -EIO;
	if (ret)
		goto out_node;

	crc = crc32(0, node, sizeof(struct jffs2_unknown_node)-4);
	if (je32_to_cpu(node->u.hdr_crc) != crc) {
		printk(KERN_WARNING "Header CRC failed on REF_PRISTINE node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
		       ref_offset(raw), je32_to_cpu(node->u.hdr_crc), crc);
		goto bail;
	}

	switch(je16_to_cpu(node->u.nodetype)) {
	case JFFS2_NODETYPE_INODE:
		crc = crc32(0, node, sizeof(node->i)-8);
		if (je32_to_cpu(node->i.node_crc) != crc) {
			printk(KERN_WARNING "Node CRC failed on REF_PRISTINE data node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
			       ref_offset(raw), je32_to_cpu(node->i.node_crc), crc);
			goto bail;
		}

		if (je32_to_cpu(node->i.dsize)) {
			crc = crc32(0, node->i.data, je32_to_cpu(node->i.csize));
			if (je32_to_cpu(node->i.data_crc) != crc) {
				printk(KERN_WARNING "Data CRC failed on REF_PRISTINE data node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
				       ref_offset(raw), je32_to_cpu(node->i.data_crc), crc);
				goto bail;
			}
		}
		break;

	case JFFS2_NODETYPE_DIRENT:
		crc = crc32(0, node, sizeof(node->d)-8);
		if (je32_to_cpu(node->d.node_crc) != crc) {
			printk(KERN_WARNING "Node CRC failed on REF_PRISTINE dirent node at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
			       ref_offset(raw), je32_to_cpu(node->d.node_crc), crc);
			goto bail;
		}

		if (node->d.nsize) {
			crc = crc32(0, node->d.name, node->d.nsize);
			if (je32_to_cpu(node->d.name_crc) != crc) {
				printk(KERN_WARNING "Name CRC failed on REF_PRISTINE dirent ode at 0x%08x: Read 0x%08x, calculated 0x%08x\n",
				       ref_offset(raw), je32_to_cpu(node->d.name_crc), crc);
				goto bail;
			}
		}
		break;
	default:
		printk(KERN_WARNING "Unknown node type for REF_PRISTINE node at 0x%08x: 0x%04x\n", 
		       ref_offset(raw), je16_to_cpu(node->u.nodetype));
		goto bail;
	}

	nraw = jffs2_alloc_raw_node_ref();
	if (!nraw) {
		ret = -ENOMEM;
		goto out_node;
	}

	/* OK, all the CRCs are good; this node can just be copied as-is. */
 retry:
	nraw->flash_offset = phys_ofs;
	nraw->__totlen = rawlen;
	nraw->next_phys = NULL;

	ret = jffs2_flash_write(c, phys_ofs, rawlen, &retlen, (char *)node);

	if (ret || (retlen != rawlen)) {
		printk(KERN_NOTICE "Write of %d bytes at 0x%08x failed. returned %d, retlen %zd\n",
                       rawlen, phys_ofs, ret, retlen);
		if (retlen) {
                        /* Doesn't belong to any inode */
			nraw->next_in_ino = NULL;

			nraw->flash_offset |= REF_OBSOLETE;
			jffs2_add_physical_node_ref(c, nraw);
			jffs2_mark_node_obsolete(c, nraw);
		} else {
			printk(KERN_NOTICE "Not marking the space at 0x%08x as dirty because the flash driver returned retlen zero\n", nraw->flash_offset);
                        jffs2_free_raw_node_ref(nraw);
		}
		if (!retried && (nraw == jffs2_alloc_raw_node_ref())) {
			/* Try to reallocate space and retry */
			uint32_t dummy;
			struct jffs2_eraseblock *jeb = &c->blocks[phys_ofs / c->sector_size];

			retried = 1;

			D1(printk(KERN_DEBUG "Retrying failed write of REF_PRISTINE node.\n"));
			
			ACCT_SANITY_CHECK(c,jeb);
			D1(ACCT_PARANOIA_CHECK(jeb));

			ret = jffs2_reserve_space_gc(c, rawlen, &phys_ofs, &dummy);

			if (!ret) {
				D1(printk(KERN_DEBUG "Allocated space at 0x%08x to retry failed write.\n", phys_ofs));

				ACCT_SANITY_CHECK(c,jeb);
				D1(ACCT_PARANOIA_CHECK(jeb));

				goto retry;
			}
			D1(printk(KERN_DEBUG "Failed to allocate space to retry failed write: %d!\n", ret));
			jffs2_free_raw_node_ref(nraw);
		}

		if (!ret)
			ret = -EIO;
		goto out_node;
	}
	nraw->flash_offset |= REF_PRISTINE;
	jffs2_add_physical_node_ref(c, nraw);

	/* Link into per-inode list. This is safe because of the ic
	   state being INO_STATE_GC. Note that if we're doing this
	   for an inode which is in-code, the 'nraw' pointer is then
	   going to be fetched from ic->nodes by our caller. */
        nraw->next_in_ino = ic->nodes;
        ic->nodes = nraw;

	jffs2_mark_node_obsolete(c, raw);
	D1(printk(KERN_DEBUG "WHEEE! GC REF_PRISTINE node at 0x%08x succeeded\n", ref_offset(raw)));

 out_node:
	kfree(node);
	return ret;
 bail:
	ret = -EBADFD;
	goto out_node;
}

static int jffs2_garbage_collect_metadata(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
					struct jffs2_inode_info *f, struct jffs2_full_dnode *fn)
{
	struct jffs2_full_dnode *new_fn;
	struct jffs2_raw_inode ri;
	jint16_t dev;
	char *mdata = NULL, mdatalen = 0;
	uint32_t alloclen, phys_ofs;
	int ret;

	if (S_ISBLK(JFFS2_F_I_MODE(f)) ||
	    S_ISCHR(JFFS2_F_I_MODE(f)) ) {
		/* For these, we don't actually need to read the old node */
		/* FIXME: for minor or major > 255. */
		dev = cpu_to_je16(((JFFS2_F_I_RDEV_MAJ(f) << 8) | 
			JFFS2_F_I_RDEV_MIN(f)));
		mdata = (char *)&dev;
		mdatalen = sizeof(dev);
		D1(printk(KERN_DEBUG "jffs2_garbage_collect_metadata(): Writing %d bytes of kdev_t\n", mdatalen));
	} else if (S_ISLNK(JFFS2_F_I_MODE(f))) {
		mdatalen = fn->size;
		mdata = kmalloc(fn->size, GFP_KERNEL);
		if (!mdata) {
			printk(KERN_WARNING "kmalloc of mdata failed in jffs2_garbage_collect_metadata()\n");
			return -ENOMEM;
		}
		ret = jffs2_read_dnode(c, f, fn, mdata, 0, mdatalen);
		if (ret) {
			printk(KERN_WARNING "read of old metadata failed in jffs2_garbage_collect_metadata(): %d\n", ret);
			kfree(mdata);
			return ret;
		}
		D1(printk(KERN_DEBUG "jffs2_garbage_collect_metadata(): Writing %d bites of symlink target\n", mdatalen));

	}
	
	ret = jffs2_reserve_space_gc(c, sizeof(ri) + mdatalen, &phys_ofs, &alloclen);
	if (ret) {
		printk(KERN_WARNING "jffs2_reserve_space_gc of %zd bytes for garbage_collect_metadata failed: %d\n",
		       sizeof(ri)+ mdatalen, ret);
		goto out;
	}
	
	memset(&ri, 0, sizeof(ri));
	ri.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
	ri.nodetype = cpu_to_je16(JFFS2_NODETYPE_INODE);
	ri.totlen = cpu_to_je32(sizeof(ri) + mdatalen);
	ri.hdr_crc = cpu_to_je32(crc32(0, &ri, sizeof(struct jffs2_unknown_node)-4));

	ri.ino = cpu_to_je32(f->inocache->ino);
	ri.version = cpu_to_je32(++f->highest_version);
	ri.mode = cpu_to_jemode(JFFS2_F_I_MODE(f));
	ri.uid = cpu_to_je16(JFFS2_F_I_UID(f));
	ri.gid = cpu_to_je16(JFFS2_F_I_GID(f));
	ri.isize = cpu_to_je32(JFFS2_F_I_SIZE(f));
	ri.atime = cpu_to_je32(JFFS2_F_I_ATIME(f));
	ri.ctime = cpu_to_je32(JFFS2_F_I_CTIME(f));
	ri.mtime = cpu_to_je32(JFFS2_F_I_MTIME(f));
	ri.offset = cpu_to_je32(0);
	ri.csize = cpu_to_je32(mdatalen);
	ri.dsize = cpu_to_je32(mdatalen);
	ri.compr = JFFS2_COMPR_NONE;
	ri.node_crc = cpu_to_je32(crc32(0, &ri, sizeof(ri)-8));
	ri.data_crc = cpu_to_je32(crc32(0, mdata, mdatalen));

	new_fn = jffs2_write_dnode(c, f, &ri, mdata, mdatalen, phys_ofs, ALLOC_GC);

	if (IS_ERR(new_fn)) {
		printk(KERN_WARNING "Error writing new dnode: %ld\n", PTR_ERR(new_fn));
		ret = PTR_ERR(new_fn);
		goto out;
	}
	jffs2_mark_node_obsolete(c, fn->raw);
	jffs2_free_full_dnode(fn);
	f->metadata = new_fn;
 out:
	if (S_ISLNK(JFFS2_F_I_MODE(f)))
		kfree(mdata);
	return ret;
}

static int jffs2_garbage_collect_dirent(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
					struct jffs2_inode_info *f, struct jffs2_full_dirent *fd)
{
	struct jffs2_full_dirent *new_fd;
	struct jffs2_raw_dirent rd;
	uint32_t alloclen, phys_ofs;
	int ret;

	rd.magic = cpu_to_je16(JFFS2_MAGIC_BITMASK);
	rd.nodetype = cpu_to_je16(JFFS2_NODETYPE_DIRENT);
	rd.nsize = strlen(fd->name);
	rd.totlen = cpu_to_je32(sizeof(rd) + rd.nsize);
	rd.hdr_crc = cpu_to_je32(crc32(0, &rd, sizeof(struct jffs2_unknown_node)-4));

	rd.pino = cpu_to_je32(f->inocache->ino);
	rd.version = cpu_to_je32(++f->highest_version);
	rd.ino = cpu_to_je32(fd->ino);
	rd.mctime = cpu_to_je32(max(JFFS2_F_I_MTIME(f), JFFS2_F_I_CTIME(f)));
	rd.type = fd->type;
	rd.node_crc = cpu_to_je32(crc32(0, &rd, sizeof(rd)-8));
	rd.name_crc = cpu_to_je32(crc32(0, fd->name, rd.nsize));
	
	ret = jffs2_reserve_space_gc(c, sizeof(rd)+rd.nsize, &phys_ofs, &alloclen);
	if (ret) {
		printk(KERN_WARNING "jffs2_reserve_space_gc of %zd bytes for garbage_collect_dirent failed: %d\n",
		       sizeof(rd)+rd.nsize, ret);
		return ret;
	}
	new_fd = jffs2_write_dirent(c, f, &rd, fd->name, rd.nsize, phys_ofs, ALLOC_GC);

	if (IS_ERR(new_fd)) {
		printk(KERN_WARNING "jffs2_write_dirent in garbage_collect_dirent failed: %ld\n", PTR_ERR(new_fd));
		return PTR_ERR(new_fd);
	}
	jffs2_add_fd_to_list(c, new_fd, &f->dents);
	return 0;
}

static int jffs2_garbage_collect_deletion_dirent(struct jffs2_sb_info *c, struct jffs2_eraseblock *jeb, 
					struct jffs2_inode_info *f, struct jffs2_full_dirent *fd)
{
	struct jffs2_full_dirent **fdp = &f->dents;
	int found = 0;

	/* On a medium where we can't actually mark nodes obsolete
	   pernamently, such as NAND flash, we need to work out
	   whether this deletion dirent is still needed to actively
	   delete a 'real' dirent with the same name that's still
	   somewhere else on the flash. */
	if (!jffs2_can_mark_obsolete(c)) {
		struct jffs2_raw_dirent *rd;
		struct jffs2_raw_node_ref *raw;
		int ret;
		size_t retlen;
		int name_len = strlen(fd->name);
		uint32_t name_crc = crc32(0, fd->name, name_len);
		uint32_t rawlen = ref_totlen(c, jeb, fd->raw);

		rd = kmalloc(rawlen, GFP_KERNEL);
		if (!rd)
			return -ENOMEM;

		/* Prevent the erase code from nicking the obsolete node refs while
		   we're looking at them. I really don't like this extra lock but
		   can't see any alternative. Suggestions on a postcard to... */
		down(&c->erase_free_sem);

		for (raw = f->inocache->nodes; raw != (void *)f->inocache; raw = raw->next_in_ino) {

			/* We only care about obsolete ones */
			if (!(ref_obsolete(raw)))
				continue;

			/* Any dirent with the same name is going to have the same length... */
			if (ref_totlen(c, NULL, raw) != rawlen)
				continue;

			/* Doesn't matter if there's one in the same erase block. We're going to 
			   delete it too at the same time. */
			if ((raw->flash_offset & ~(c->sector_size-1)) ==
			    (fd->raw->flash_offset & ~(c->sector_size-1)))
				continue;

			D1(printk(KERN_DEBUG "Check potential deletion dirent at %08x\n", ref_offset(raw)));

			/* This is an obsolete node belonging to the same directory, and it's of the right
			   length. We need to take a closer look...*/
			ret = jffs2_flash_read(c, ref_offset(raw), rawlen, &retlen, (char *)rd);
			if (ret) {
				printk(KERN_WARNING "jffs2_g_c_deletion_dirent(): Read error (%d) reading obsolete node at %08x\n", ret, ref_offset(raw));
				/* If we can't read it, we don't need to continue to obsolete it. Continue */
				continue;
			}
			if (retlen != rawlen) {