dlw@ucbopal.CC.Berkeley.ARPA (03/08/84)
Index: /usr/src/etc/restore 4.2 Fix Description: There is an extremely serious bug in the 4.2bsd restore. You may NOT be able to restore a multi-level dump, even though the tape is readable and everything is there. The problem is actually in ``dump''. However, the kludge given below will allow (most) existing incremental dumps to be read. I will post a fix to dump asap. The problem is that the number of inodes in a filesystem is not recorded directly in the dump tape. restore infers the number from the size of the bit maps at the beginning of the tape. But the bit maps are truncated to the smallest possible size by dump before they are recorded. Thus, if the last inode USED is 3216, the map will be (roughly) that size, instead of the ``real'' number in the filesystem. Unlike any previous dump/restore, this version saves the inode and symbol table between incremental restores. If you do a level 0 on a new filesystem, few inodes are actually ``used''. Thus the map will be small. Several days later you do a level 3 dump. Lots of inodes are used. The maps are much bigger. NOW, assume you have a head crash. The level 0 restore will have made a small map and symtable because of what is on the level 0 tape. When you go to put on the level 3, BINGO! restore will complain of "corrupted directories", "expected inode M, got N", etc. This is because the inodes it finds on the tape are outside the level 0 map, etc. The ``real'' fix is to have dump always record the full map. (It isn't THAT big.) Then restore would ``work''. However, we (and you) have racks of dump tapes already. The fix below causes restore to always use a large map. This ``works'' as long as MAXINO is larger than required for your biggest filesystem. See the output of newfs for the number you require (which is ipg * ncg). Repeat-By: See above. Fix: Below is a diff of tape.c. The line numbers are slightly off because we have a few other changes in there. While I was debugging this, I was frustrated by the fact that verbose & debug output comes out randomly out of sync on stdout and stderr due to buffering. I modified restore.h to cause everything to come out on stdout. It was simpler that way. ------- diff restore.h.old restore.h ------- 6a7,9 > > #undef stderr > #define stderr stdout ------- diff tape.c.old tape.c ------- 14a15,16 > #define MAXINO 65535 /* KLUDGE! */ > 148,150c150,152 < maxino = (spcl.c_count * TP_BSIZE * NBBY) + 1; < dprintf(stdout, "maxino = %d\n", maxino); < map = calloc((unsigned)1, (unsigned)howmany(maxino, NBBY)); --- > maxino = (spcl.c_count * TP_BSIZE * NBBY) + 1; /* WRONG! */ > dprintf(stdout, "ino map size = %d\n", maxino); > map = calloc((unsigned)1, (unsigned)howmany(maxino>MAXINO?maxino:MAXINO, NBBY)); 160c162 < map = calloc((unsigned)1, (unsigned)howmany(maxino, NBBY)); --- > map = calloc((unsigned)1, (unsigned)howmany(maxino>MAXINO?maxino:MAXINO, NBBY)); 165a168,169 > if (MAXINO > maxino) > maxino = MAXINO; /* Kludge, since we don't really know */ ****** context of the 2 lines above ****** dumpmap = map; curfile.action = USING; getfile(xtrmap, xtrmapskip); if (MAXINO > maxino) maxino = MAXINO; /* Kludge, since we don't really know */ } ******************************************