There is an off by one problem with idr_get_new_above.

The comment and function name suggest that it will return an id >
starting_id, but it actually returned an id >= starting_id, and kernel
callers other than inotify treated it as such.

The patch below fixes the comment, and fixes inotifys usage.  The
function name still doesn't match the behaviour, but it never did.
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We are saving the wrong thing in ->last_wd.  We want the wd, not the
return value.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

When you rm a watch, an IN_IGNORED event is sent down the event queue
with the watch descriptor that you just rm'd.

If you then add a watch you could get the ignored watch's wd and if you
haven't read the entire event queue, user space will think that it's
newly created watch was just ignored.

To avoid this problem we just use idr_get_new_above instead of
idr_get_new.
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Cc: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Check for (unlikely) errors in the filesystem initialization stuff in
our module_init() function.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Change default inotify limits: Maximum instances per user to 128 and
maximum events per queue to 16k.  The max instances used to be 128; the
change to 8 was a mistake.  Memory consumption is fine.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Handle error out paths better.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Bug fix: Ensure that the fd passed to inotify_add_watch() and
inotify_rm_watch() belongs to inotify.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

As an optimization, use fget_light() and fput_light() where possible.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Miscellaneous invariant clean up, comment fixes, and so on.  Trivial
stuff.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NJohn McCutchan <ttb@tentacle.dhs.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Really simple, basic cleanup.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This moves the inotify sysctl knobs to "/proc/sys/fs/inotify" from
"/proc/sys/fs".  Also some related cleanup.
Signed-off-by: NRobert Love <rml@novell.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

inotify is intended to correct the deficiencies of dnotify, particularly
its inability to scale and its terrible user interface:

        * dnotify requires the opening of one fd per each directory
          that you intend to watch. This quickly results in too many
          open files and pins removable media, preventing unmount.
        * dnotify is directory-based. You only learn about changes to
          directories. Sure, a change to a file in a directory affects
          the directory, but you are then forced to keep a cache of
          stat structures.
        * dnotify's interface to user-space is awful.  Signals?

inotify provides a more usable, simple, powerful solution to file change
notification:

        * inotify's interface is a system call that returns a fd, not SIGIO.
	  You get a single fd, which is select()-able.
        * inotify has an event that says "the filesystem that the item
          you were watching is on was unmounted."
        * inotify can watch directories or files.

Inotify is currently used by Beagle (a desktop search infrastructure),
Gamin (a FAM replacement), and other projects.

See Documentation/filesystems/inotify.txt.
Signed-off-by: NRobert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>