panic: ffs_reallocblk: start == end

[Kris Kennaway]

Kris Kennaway wrote:
> I got this panic on an 8 core amd64 running 8.0 when writing to a ufs on 
> a md device:
> 
> panic: ffs_reallocblk: start == end
> 
> db> wh
> Tracing pid 59911 tid 100115 td 0xffffff0003b90000
> kdb_enter() at kdb_enter+0x31
> panic() at panic+0x1c0
> ffs_reallocblks() at ffs_reallocblks+0xb11
> VOP_REALLOCBLKS_APV() at VOP_REALLOCBLKS_APV+0xb9
> cluster_write() at cluster_write+0x38a
> ffs_write() at ffs_write+0x575
> VOP_WRITE_APV() at VOP_WRITE_APV+0x147
> vn_write() at vn_write+0x213
> dofilewrite() at dofilewrite+0x9a
> kern_writev() at kern_writev+0x4f
> write() at write+0x4b
> syscall() at syscall+0x301
> Xfast_syscall() at Xfast_syscall+0xab
> --- syscall (4, FreeBSD ELF64, write), rip = 0x800a65d0c, rsp = 
> 0x7fffffffd268, rbp = 0x2800 ---
> 
> Kris
> 

Another one of these on a different machine.  Looks like something is 
definitely broken.

Kris