[PATCH FOR REVIEW] fsck_ffs: Recover from catastrophic damage

Xin LI delphij at delphij.net
Fri Feb 22 01:00:34 UTC 2008


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Xin LI wrote:
> Here is a revised version of patch.

Sorry for replying myself.  I found a nit - the clear of cg is beyond
the reach of later phases, so set rerun = 1 to advise the user that a
rerun of fsck is necessary to make a full recover.  No other functional
chnages.

Cheers,
- --
Xin LI <delphij at delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!
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-------------- next part --------------
Index: fsck.h
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/fsck.h,v
retrieving revision 1.37
diff -u -p -r1.37 fsck.h
--- fsck.h	31 Oct 2006 22:06:56 -0000	1.37
+++ fsck.h	21 Feb 2008 22:01:44 -0000
@@ -270,6 +270,7 @@ char	yflag;			/* assume a yes response *
 int	bkgrdflag;		/* use a snapshot to run on an active system */
 int	bflag;			/* location of alternate super block */
 int	debug;			/* output debugging info */
+char	catastrophicflag;	/* run in catastrophic mode */
 int	cvtlevel;		/* convert to newer file system format */
 int	bkgrdcheck;		/* determine if background check is possible */
 int	bkgrdsumadj;		/* whether the kernel have ability to adjust superblock summary */
@@ -335,6 +336,7 @@ void		cacheino(union dinode *dp, ino_t i
 void		catch(int);
 void		catchquit(int);
 int		changeino(ino_t dir, const char *name, ino_t newnum);
+void		check_cgmagic(int cg, struct cg *cgp);
 int		chkrange(ufs2_daddr_t blk, int cnt);
 void		ckfini(int markclean);
 int		ckinode(union dinode *dp, struct inodesc *);
Index: fsck_ffs.8
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/fsck_ffs.8,v
retrieving revision 1.34
diff -u -p -r1.34 fsck_ffs.8
--- fsck_ffs.8	20 Sep 2005 08:02:38 -0000	1.34
+++ fsck_ffs.8	21 Feb 2008 22:26:08 -0000
@@ -38,7 +38,7 @@
 .Nd file system consistency check and interactive repair
 .Sh SYNOPSIS
 .Nm
-.Op Fl BFpfny
+.Op Fl BCFpfny
 .Op Fl b Ar block
 .Op Fl c Ar level
 .Op Fl m Ar mode
@@ -175,6 +175,26 @@ Use the block specified immediately afte
 the super block for the file system.
 An alternate super block is usually located at block 32 for UFS1,
 and block 160 for UFS2.
+.It Fl C
+Run
+.Nm
+in 'catastrophic recovery' mode, which will enable certain aggressive
+operations that can make
+.Nm
+to survive with file systems that has very serious data damage, which
+is an useful last resort when on disk data damage is very serious
+and causes
+.Nm
+to crash otherwise.  Be
+.Em very careful
+using this flag, is dangerous if there are data transmission hazards
+because a false positive cylinder group magic number mismatch could
+cause
+.Em irrevertible data loss!
+.Pp
+This option implies the
+.Fl f
+flag.
 .It Fl c
 Convert the file system to the specified level.
 Note that the level of a file system can only be raised.
Index: fsutil.c
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/fsutil.c,v
retrieving revision 1.26
diff -u -p -r1.26 fsutil.c
--- fsutil.c	31 Oct 2006 22:06:56 -0000	1.26
+++ fsutil.c	22 Feb 2008 00:50:43 -0000
@@ -301,7 +301,7 @@ ckfini(int markclean)
 	if (havesb && cursnapshot == 0 && sblock.fs_magic == FS_UFS2_MAGIC &&
 	    sblk.b_bno != sblock.fs_sblockloc / dev_bsize &&
 	    !preen && reply("UPDATE STANDARD SUPERBLOCK")) {
-		sblk.b_bno = sblock.fs_sblockloc / dev_bsize;
+		sblk.b_bno = SBLOCK_UFS2 / dev_bsize;
 		sbdirty();
 		flush(fswritefd, &sblk);
 	}
@@ -418,6 +418,35 @@ blwrite(int fd, char *buf, ufs2_daddr_t 
 }
 
 /*
+ * Check cg's magic number.  If catastrophic mode is enabled and the cg's
+ * magic number is bad, offer an option to clear the whole cg.
+ */
+void
+check_cgmagic(int cg, struct cg *cgp)
+{
+
+	if (!cg_chkmagic(cgp)) {
+	    pwarn("CG %d: BAD MAGIC NUMBER\n", cg);
+	    if (catastrophicflag) {
+		if (reply("CLEAR CG")) {
+			memset(cgp, 0, (size_t)sblock.fs_cgsize);
+			cgp->cg_initediblk = sblock.fs_ipg;
+			cgp->cg_old_niblk = sblock.fs_ipg;
+			cgp->cg_old_ncyl = sblock.fs_old_cpg;
+			cgp->cg_cgx = cg;
+			cgp->cg_niblk = sblock.fs_ipg;
+			cgp->cg_ndblk = sblock.fs_size - cgbase(&sblock, cg);
+			cgp->cg_magic = CG_MAGIC;
+			cgdirty();
+			printf("PLEASE RERUN FSCK.\n");
+			rerun = 1;
+		}
+	    } else
+		printf("YOU MAY NEED TO RERUN FSCK WITH -C IF IT CRASHED.\n");
+	}
+}
+
+/*
  * allocate a data block with the specified number of fragments
  */
 ufs2_daddr_t
@@ -441,8 +470,7 @@ allocblk(long frags)
 			}
 			cg = dtog(&sblock, i + j);
 			getblk(&cgblk, cgtod(&sblock, cg), sblock.fs_cgsize);
-			if (!cg_chkmagic(cgp))
-				pfatal("CG %d: BAD MAGIC NUMBER\n", cg);
+			check_cgmagic(cg, cgp);
 			baseblk = dtogd(&sblock, i + j);
 			for (k = 0; k < frags; k++) {
 				setbmap(i + j + k);
Index: inode.c
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/inode.c,v
retrieving revision 1.38
diff -u -p -r1.38 inode.c
--- inode.c	31 Oct 2006 22:06:56 -0000	1.38
+++ inode.c	21 Feb 2008 21:56:27 -0000
@@ -617,8 +617,7 @@ allocino(ino_t request, int type)
 		return (0);
 	cg = ino_to_cg(&sblock, ino);
 	getblk(&cgblk, cgtod(&sblock, cg), sblock.fs_cgsize);
-	if (!cg_chkmagic(cgp))
-		pfatal("CG %d: BAD MAGIC NUMBER\n", cg);
+	check_cgmagic(cg, cgp);
 	setbit(cg_inosused(cgp), ino % sblock.fs_ipg);
 	cgp->cg_cs.cs_nifree--;
 	switch (type & IFMT) {
Index: main.c
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/main.c,v
retrieving revision 1.47
diff -u -p -r1.47 main.c
--- main.c	19 Sep 2007 01:24:19 -0000	1.47
+++ main.c	21 Feb 2008 22:02:42 -0000
@@ -81,7 +81,8 @@ main(int argc, char *argv[])
 
 	sync();
 	skipclean = 1;
-	while ((ch = getopt(argc, argv, "b:Bc:dfFm:npy")) != -1) {
+	catastrophicflag = 0;
+	while ((ch = getopt(argc, argv, "b:Bc:CdfFm:npy")) != -1) {
 		switch (ch) {
 		case 'b':
 			skipclean = 0;
@@ -105,6 +106,10 @@ main(int argc, char *argv[])
 			debug++;
 			break;
 
+		case 'C':
+			catastrophicflag = 1;
+			/* FALLTHROUGH */
+
 		case 'f':
 			skipclean = 0;
 			break;
Index: pass1.c
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/pass1.c,v
retrieving revision 1.43
diff -u -p -r1.43 pass1.c
--- pass1.c	8 Oct 2004 20:44:47 -0000	1.43
+++ pass1.c	20 Feb 2008 07:13:53 -0000
@@ -93,9 +93,11 @@ pass1(void)
 		inumber = c * sblock.fs_ipg;
 		setinodebuf(inumber);
 		getblk(&cgblk, cgtod(&sblock, c), sblock.fs_cgsize);
-		if (sblock.fs_magic == FS_UFS2_MAGIC)
+		if (sblock.fs_magic == FS_UFS2_MAGIC) {
 			inosused = cgrp.cg_initediblk;
-		else
+			if (inosused > sblock.fs_ipg)
+				inosused = sblock.fs_ipg;
+		} else
 			inosused = sblock.fs_ipg;
 		if (got_siginfo) {
 			printf("%s: phase 1: cyl group %d of %d (%d%%)\n",
Index: pass2.c
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/pass2.c,v
retrieving revision 1.26
diff -u -p -r1.26 pass2.c
--- pass2.c	8 Oct 2004 20:44:47 -0000	1.26
+++ pass2.c	21 Feb 2008 22:31:03 -0000
@@ -242,6 +242,8 @@ pass2check(struct inodesc *idesc)
 	/*
 	 * check for "."
 	 */
+	if (dirp->d_ino > maxino)
+		goto chk2;
 	if (idesc->id_entryno != 0)
 		goto chk1;
 	if (dirp->d_ino != 0 && strcmp(dirp->d_name, ".") == 0) {
Index: setup.c
===================================================================
RCS file: /home/ncvs/src/sbin/fsck_ffs/setup.c,v
retrieving revision 1.50
diff -u -p -r1.50 setup.c
--- setup.c	31 Oct 2006 22:06:56 -0000	1.50
+++ setup.c	20 Feb 2008 07:13:27 -0000
@@ -349,7 +349,7 @@ readsb(int listerr)
 			      sblock.fs_sblockloc == sblock_try[i])) &&
 			    sblock.fs_ncg >= 1 &&
 			    sblock.fs_bsize >= MINBSIZE &&
-			    sblock.fs_bsize >= sizeof(struct fs))
+			    sblock.fs_sbsize >= roundup(sizeof(struct fs), dev_bsize))
 				break;
 		}
 		if (sblock_try[i] == -1) {


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