[BUG] fs/afs/flock: possible sleep-in-atomic bugs in afs_do_setlk

[Jia-Ju Bai]

According to fs/afs/flock.c, the kernel may sleep under a spinlock,
and the function call paths are:
afs_do_setlk (acquire the spinlock: inode->i_lock)
  afs_vnode_fetch_status
    schedule --> may sleep

afs_do_setlk (acquire the spinlock: inode->i_lock)
  wait_event_interruptible --> may sleep

These bugs may be introduced by only considering "vnode->lock" but 
ignoring "inode->i_lock".

A possible fix is to unlock "inode->i_lock" before calling 
afs_vnode_fetch_status and wait_event_interruptible, and lock 
"inode->i_lock" again after them.

These bugs are found by my static analysis tool and my code review.


Thanks,
Jia-Ju Bai