code: mafs

ref: 4210fbecf4d94bd5873037bc3f5c721f47f42a2c
dir: /free.c/

#include <u.h>
#include <libc.h>
#include "dat.h"
#include "fns.h"
#include "extents.h"

/*
	go through the contents of Bfrees and write out the list of free blocks
	used by reconcile.c to identify discrepancies
 */

Extents frees;
int chatty9p = 0;
char *devfile = nil;
void walkdentry(u64 blkno);
int checkdentry(u64 blkno, u8 tag, u64 qpath);
void getfrees(u64 dblkno);

static void
usage(void)
{
	fprint(2, "usage: free [-D ] fsfile\n");
	exits("usage");
}

void
main(int argc, char *argv[])
{
	u64 size;

	ARGBEGIN{
	default:	usage();
	case 'D':	chatty9p++; break;
	}ARGEND

	if(argc != 1)
		usage();

	devfile = argv[0];
	if(devfile == nil)
		sysfatal("no disk file");

	if (access(devfile, AREAD) == -1)
		sysfatal("%s cannot access device", devfile);

	size = devinit(devfile);
	if(size == 0)
		panic("null size %s", devfile);
	if(chatty9p)
		print("%s %llud bytes %llud blocks\n", devfile, size, size/Blocksize);

	checkdentry(Bdfrees, Tdentry, Qpfrees);
	initextents(&frees, "frees");
	getfrees(Bdfrees);
	showextents(1, "", &frees);
	// showblocknos(1, &frees);
	close(devfd);
	exits(0);
}

int
checkvalid(u64 blkno, u8 dtag, u64 dpath, u8 tag, u64 qpath, u16 len)
{
	if(dtag != tag || dpath != qpath){
		/* if(chatty9p) */
			fprint(2, "check invalid %llud tag/path expected %s/%llud actual %s/%llud\n",
					blkno, tagnames[tag], qpath, tagnames[dtag], dpath);
		fprint(2, "free: %llud\n", blkno);
		return 0;
	}
	if(chatty9p)
		print("%llud %d\n", blkno, len);
	return 1;
}

int
checkdentry(u64 blkno, u8 tag, u64 qpath)
{
	u8 buf[Metadatablocksize];
	Dentry *t;

	devread(blkno, buf, Metadataunits);
	t = (Dentry*)buf;
	return checkvalid(blkno, t->tag, t->path, tag, qpath, Metadataunits);
}

void
loadfreeextents(u64 blkno)
{
	s8 *buf;

	buf = emalloc(Metadatablocksize);
	devread(blkno, buf, Metadataunits);
	loadextents(&frees, buf, Maxdatablocksize);
	free(buf);
}

void
walkindir(u64 blkno, u16 tag, u16 bottomtag, u64 qpath)
{
	u8 buf[Metadatablocksize];
	Indirect *t;
	u64 cblkno;
	int i;

	devread(blkno, buf, Metadataunits);
	t = (Indirect*)buf;
	if(checkvalid(blkno, t->tag, t->path, tag, qpath, Metadataunits)){
		if(t->tag == Tind0){
			for(i = 0; i<Nindperblock; i++){
				cblkno = t->bufa[i];
				if(cblkno == 0)
					return;
				loadfreeextents(cblkno);
			}
		}else{
			for(i = 0; i<Nindperblock; i++){
				cblkno = t->bufa[i];
				if(cblkno == 0)
					return;
				/* check tag */
				walkindir(cblkno, tag-1,  bottomtag, qpath);
			}
		}
	}
}

void
getfrees(u64 dblkno)
{
	u64 size;
	u8 buf[Metadatablocksize];
	Dentry *d;
	u64 cblkno;
	int i;

	devread(dblkno, buf, Metadataunits);
	recentmetadata(buf, &d, nil);
	size = d->size;
	if(size == 0)
		panic("loadfreeextents size == 0");

	if(d->size <= Ddatasize){
		loadextents(&frees, d->buf, d->size);
		return;
	}
	if(checkvalid(dblkno, d->tag, d->path, Tdentry, Qpfrees, Metadataunits)){
		for(i = 0; i<Ndblock; i++){
			cblkno = d->dblocks[i];
			if(cblkno == 0)
				return;
			loadfreeextents(cblkno);
		}
		for(i = Tind0; i<Niblock+Tind0; i++){
			cblkno = d->iblocks[i];
			if(cblkno == 0)
				return;
			walkindir(cblkno, i, Tdata, Qpfrees);
		}
	}
}