Description of problem:

If you try to dump an ext2 file system that is not listed in
/etc/fstab, and the root file system is XFS, dump aborts after
opening and reading the super block from the XFS root file system.

How reproducible:
Always

Steps to Reproduce:
1.root file system is XFS, ext2 file system is not listed in /etc/fstab
2.mount ext2 file system on mount point
3.attempt to dump the ext2 file system
	
Actual Results:
# dump -0 -f /tmp/foo.dmp /mnt
  DUMP: Date of this level 0 dump: Thu Oct  3 14:56:53 2002
  DUMP: Dumping /dev/sda2 (/ (dir mnt)) to /tmp/foo.dmp
/dev/sda2: Bad magic number in super-block while opening filesystem
  DUMP: The ENTIRE dump is aborted.


Additional info:

Example:

# mount /dev/sdb1 /mnt

# mount
/dev/xscsi/pci00.01.0-1/target0/lun0/part2 on / type xfs (rw)
none on /proc type proc (rw)
devfs on /dev type devfs (rw)
/dev/sda1 on /boot/efi type vfat (rw)
none on /dev/pts type devpts (rw,gid=5,mode=620)
none on /dev/shm type tmpfs (rw)
/dev/sdb1 on /mnt type ext2 (rw)

# dump -0 -f /tmp/foo.dmp /mnt
  DUMP: Date of this level 0 dump: Thu Oct  3 14:56:53 2002
  DUMP: Dumping /dev/sda2 (/ (dir mnt)) to /tmp/foo.dmp
/dev/sda2: Bad magic number in super-block while opening filesystem
  DUMP: The ENTIRE dump is aborted.

strace shows it reading /etc/fstab, then opening /dev/sda2 (the
root XFS file system) and attempting to read the superblock, then
aborting:

     0.000355 open("/etc/fstab", O_RDONLY) = 3
     0.000310 SYS_1212(0x3, 0x60000fffffff7e80, 0, 0, 0, 0, 0, 0) = 0
     0.000314 mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0) = 0x2000000000000000
     0.000221 read(3, "/dev/sda2\t\t/                    "..., 16384) = 519
     0.000574 read(3, "", 16384)        = 0
     0.000151 close(3)                  = 0
     0.000153 munmap(0x2000000000000000, 65536) = 0
     0.000255 SYS_1211(0x60000fffffff7630, 0x60000fffffff8640, 0x1b8,
0x6000000000014218, 0x4000000000082880, 0xc00000000000040c, 0x2000000000000000,
0x10000) = 0
     0.000204 SYS_1210(0x60000fffffff98c0, 0x60000fffffff86b0, 0x101, 0xf000,
0x2f, 0x24, 0x4000000000068720, 0xc000000000000287) = 0
     0.000167 uname({sys="Linux", node="dhcp-163-154-10-100", ...}) = 0
     0.000491 SYS_1210(0x600000000000f968, 0x60000fffffff8830,
0x6000000000015450, 0x40000000000033c0, 0xc000000000000b1e, 0x1,
0x60000fffffff98c0, 0x60000fffffff86b0) = 0
     0.000248 open("/etc/localtime", O_RDONLY) = 3
     0.000291 SYS_1212(0x3, 0x60000fffffff8560, 0x4000000000086f70,
0xc00000000000040a, 0, 0x10000, 0x3, 0x22) = 0
     0.000244 mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS,
-1, 0) = 0x2000000000000000
     0.000242 read(3,
"TZif\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\4\0\0\0\4\0"..., 16384) = 1027
     0.000424 close(3)                  = 0
     0.000155 munmap(0x2000000000000000, 65536) = 0
     0.000265 write(2, "  DUMP: ", 8)   = 8
     0.000370 write(2, "Date of this level 0 dump: Thu O"..., 52) = 52
     0.000332 write(2, "  DUMP: ", 8)   = 8
     0.000234 write(2, "Dumping /dev/sda2 (/ (dir mnt)) ", 32) = 32
     0.000286 write(2, "to /tmp/foo.dmp\n", 16) = 16
     0.000202 open("/dev/sda2", O_RDONLY) = 3
     0.008315 ioctl(3, 0x1261, 0)       = 0
     0.214715 brk(0x600000000001c000)   = 0x600000000001c000
     0.000281 open("/dev/sda2", O_RDONLY) = 4
     0.005378 lseek(4, 1024, SEEK_SET)  = 1024
     0.000196 read(4,
"XAGI\0\0\0\1\0\0\0\0\0\1\0\0\0\0!\200\0\0\0\3\0\0\0\1\0"..., 1024) = 1024
     0.000375 close(4)                  = 0
     0.013156 write(2, "/dev/sda2", 9)  = 9
     0.000472 write(2, ": ", 2)         = 2
     0.000373 write(2, "Bad magic number in super-block", 31) = 31
     0.000300 write(2, " ", 1)          = 1
     0.000272 write(2, "while opening filesystem", 24) = 24
     0.000218 write(2, "\r", 1)         = 1
     0.000254 write(2, "\n", 1)         = 1
     0.000233 write(2, "  DUMP: ", 8)   = 8
     0.000261 write(2, "The ENTIRE dump is aborted.\n", 28) = 28
     0.000210 exit(1)                   = ?