Revert "fsnotify: store struct file not struct path"

Revert "fsnotify: store struct file not struct path"

This reverts commit feea98dff157b2db7b2759f64eee152936179fd5 (and the
accompanying commit 8b0956f65351 "vfs/fsnotify: fsnotify_close can delay
the final work in fput" that was a horribly ugly hack to make it work at
all).

The 'struct file' approach not only causes that disgusting hack, it
somehow breaks pulseaudio, probably due to some other subtlety with
f_count handling.

Fix up various conflicts due to later fsnotify work.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>