Revert "fuse: move initialization of fuse_file to fuse_writepages() instead of in callback"
This reverts commit
672c3b7457fcee9656c36a29a4b21ec4a652433e.
fuse_writepages() might be called with no dirty pages after all writable
opens were closed. In this case __fuse_write_file_get() will return NULL
which will trigger the WARNING.
The exact conditions under which this is triggered is unclear and syzbot
didn't find a reproducer yet.
Reported-by: syzbot+217a976dc26ef2fa8711@syzkaller.appspotmail.com
Link: https://lore.kernel.org/all/CAJnrk1aQwfvb51wQ5rUSf9N8j1hArTFeSkHqC_3T-mU6_BCD=A@mail.gmail.com/
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>