Frequent WAPBL panics

[Geoff Wing <gcw%pobox.com@localhost>]

Heyla,
I'm frequently getting
  panic: kernel diagnostic assertion "head == off" failed: file
    "../../../../kern/vfs_wapbl.c", line 1397
with kernels from the last few days.

#18 0xc0348ca1 in wapbl_flush (wl=0xc2d20500, waitfor=0) at 
../../../../kern/vfs_wapbl.c:1397
#19 0xc0250254 in ffs_full_fsync (vp=0xcdc4d5c8, flags=<value optimized out>) 
at ../../../../ufs/ffs/ffs_vnops.c:470
#20 0xc02506fd in ffs_fsync (v=0xcdbb2cc8) at 
../../../../ufs/ffs/ffs_vnops.c:301
#21 0xc034b039 in VOP_FSYNC (vp=0xcdc4d5c8, cred=0xcbe66f00, flags=8, offlo=0, 
offhi=0) at ../../../../kern/vnode_if.c:804
#22 0xc0352e3b in sched_sync (v=0xcdb830c0) at 
../../../../miscfs/syncfs/sync_subr.c:223
#23 0xc01002c1 in lwp_trampoline ()

(gdb) p head
$1 = 312832
(gdb) p tail
$2 = 1024
(gdb) p off
$3 = 321024
(gdb) p flushsize
$4 = 311808
(gdb) p *wl
$5 = {wl_logvp = 0xcdc4d5c8, wl_devvp = 0xcdc4d5c8, wl_mount = 0xcdc8c000, 
  wl_logpbn = 2126080, wl_log_dev_bshift = 9, wl_fs_dev_bshift = 9, 
  wl_lock_count = 0, wl_circ_size = 2071552, wl_circ_off = 1024, 
  wl_bufcount_max = 35651584, wl_bufbytes_max = 2068480, wl_head = 0, 
  wl_tail = 0, wl_wc_header = 0xc2d4f800, wl_wc_scratch = 0xc2d4f600, 
  wl_mtx = {u = {mtxa_owner = 4}}, wl_rwlock = {rw_owner = 3451400396}, 
  wl_flush = 0xc0252f24 <ffs_wapbl_sync_metadata>, 
  wl_flush_abort = 0xc0252e98 <ffs_wapbl_abort_sync_metadata>, 
  wl_bufbytes = 317440, wl_bufcount = 48, wl_bcount = 309248, wl_bufs = {
    lh_first = 0xc40b4650}, wl_reclaimable_cv = {cv_opaque = {0x0, 
      0xc2d20568}, cv_wmesg = 0xc0530f77 "wapblrec"}, 
  wl_reclaimable_bytes = 0, wl_error_count = 0, wl_reserved_bytes = 0, 
  wl_deallocblks = 0xc2d95000, wl_dealloclens = 0xc2da5000, 
  wl_dealloccnt = 34, wl_dealloclim = 8080, wl_inohash = 0xcdc8c914, 
  wl_inohashmask = 127, wl_inohashcnt = 0, wl_entries = {sqh_first = 0x0, 
    sqh_last = 0xc2d2059c}}

Clues, anyone?

Anyone else?

Regards,
Geoff