[PATCH] inotify

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: Robert Love <rml@novell.com>
Cc: John McCutchan <ttb@tentacle.dhs.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/fs/Kconfig b/fs/Kconfig
index f93fd41b025d..5d0c4be43dba 100644
--- a/fs/Kconfig
+++ b/fs/Kconfig
@@ -359,6 +359,19 @@ config ROMFS_FS
           If you don't know whether you need it, then you don't need it:
           answer N.
 
+config INOTIFY
+        bool "Inotify file change notification support"
+        default y
+        ---help---
+          Say Y here to enable inotify support and the /dev/inotify character
+          device.  Inotify is a file change notification system and a
+          replacement for dnotify.  Inotify fixes numerous shortcomings in
+          dnotify and introduces several new features.  It allows monitoring
+          of both files and directories via a single open fd.  Multiple file
+          events are supported.
+
+          If unsure, say Y.
+
 config QUOTA
         bool "Quota support"
         help