[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, 9 insertions, 6 deletions

diff --git a/fs/read_write.c b/fs/read_write.c
index 9292f5fa4d62..563abd09b5c8 100644
--- a/fs/read_write.c
+++ b/fs/read_write.c
@@ -10,7 +10,7 @@
 #include <linux/file.h>
 #include <linux/uio.h>
 #include <linux/smp_lock.h>
-#include <linux/dnotify.h>
+#include <linux/fsnotify.h>
 #include <linux/security.h>
 #include <linux/module.h>
 #include <linux/syscalls.h>
@@ -252,7 +252,7 @@ ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
                         else
                                 ret = do_sync_read(file, buf, count, pos);
                         if (ret > 0) {
-                                dnotify_parent(file->f_dentry, DN_ACCESS);
+                                fsnotify_access(file->f_dentry);
                                 current->rchar += ret;
                         }
                         current->syscr++;
@@ -303,7 +303,7 @@ ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_
                         else
                                 ret = do_sync_write(file, buf, count, pos);
                         if (ret > 0) {
-                                dnotify_parent(file->f_dentry, DN_MODIFY);
+                                fsnotify_modify(file->f_dentry);
                                 current->wchar += ret;
                         }
                         current->syscw++;
@@ -539,9 +539,12 @@ static ssize_t do_readv_writev(int type, struct file *file,
 out:
         if (iov != iovstack)
                 kfree(iov);
-        if ((ret + (type == READ)) > 0)
-                dnotify_parent(file->f_dentry,
-                                (type == READ) ? DN_ACCESS : DN_MODIFY);
+        if ((ret + (type == READ)) > 0) {
+                if (type == READ)
+                        fsnotify_access(file->f_dentry);
+                else
+                        fsnotify_modify(file->f_dentry);
+        }
         return ret;
 Efault:
         ret = -EFAULT;