DragonFlyBSD

Just now, twice, also on a fsck'ed system:

panic: msdosfs_reinsert: insertion failed 16

#2 0xc0195c35 in panic (fmt=0xe390b2c0 "msdosfs_reinsert: insertion failed %d")
at /usr/src/sys/kern/kern_shutdown.c:800
bootopt = 256
newpanic = 1
ap = 0xe3774a20 "\020"
buf = "msdosfs_reinsert: insertion failed 16", '\0' <repeats 218 times>
#3 0xe3903a55 in msdosfs_reinsert (ip=0xe2bcd8a8, new_dirclust=994439,
new_diroffset=224)
at /usr/src/sys/vfs/msdosfs/msdosfs_denode.c:225
ilock = {tr_tok = 0xe390cd1c, tr_next = 0x0, tr_state = 1}
error = 0
#4 0xe39093a0 in msdosfs_rename (ap=0xe3774acc) at
/usr/src/sys/vfs/msdosfs/msdosfs_vnops.c:1274
new_dirclust = 994439
new_diroffset = 0
tdvp = (struct vnode *) 0xe7d3d968
fvp = (struct vnode *) 0xe3a21ee8
fdvp = (struct vnode *) 0xe7d3d968
tvp = (struct vnode *) 0x0
tcnp = (struct componentname *) 0xe3774b3c
fcnp = (struct componentname *) 0xe3774b5c
ip = (struct denode *) 0xe2bcd8a8
xp = (struct denode *) 0x0
dp = (struct denode *) 0xe2a2ad30
zp = (struct denode *) 0xe2a2ad30
toname = "ALBUMA~1JPG"
oldname = "ALBUMA~1RST"
from_diroffset = 1088
to_diroffset = 224
doingdirectory = 0
cn = <value optimized out>
pmp = (struct msdosfsmount *) 0xe32e91c8
dotdotp = <value optimized out>
bp = <value optimized out>

happend when calling rsync -aPv /dir/on/hammer /dir/on/msdosfs

crashdump available on request (mega huge one)