fs/ntfs3: don't hold ni_lock when calling truncate_setsize()

In the Linux kernel, the following vulnerability has been resolved:

fs/ntfs3: don't hold ni_lock when calling truncate_setsize()

syzbot is reporting hung task at do_user_addr_fault() [1], for there is

a silent deadlock between PG_locked bit and ni_lock lock.

Since filemap_update_page() calls filemap_read_folio() after calling

folio_trylock() which will set PG_locked bit, ntfs_truncate() must not

call truncate_setsize() which will wait for PG_locked bit to be cleared

when holding ni_lock lock.