Hi,
thank you very much for your bug report! This bug has existed since the first version of OSXUFSE and is related to the locking code that makes the kernel extension thread-safe. The solution should be relatively simple: unlock biglock before calling ubc_setsize. I'm afraid there is nothing you can try to fox this besides updating to OSXFUSE 2.4.1, once it is available.
For everyone interested, here is the symbolicated stack trace:
panic
fusefs_recursive_lock_lock
fuse_biglock_vnop_pagein
VNOP_PAGEIN
vnode_pagein
vnode_pager_cluster_read
vnode_pager_data_request
vm_fault_page
vm_object_update
memory_object_lock_request
ubc_setsize
fuse_vnop_setattr
fuse_biglock_vnop_setattr
VNOP_SETATTR
vnode_setattr
vnode_setsize
open1
open_nocancel
unix_syscall64
lo64_unix_scall
Regards,
Benjamin