Revert mount/umount uevent removal

This change reverts the 033b96fd30db52a710d97b06f87d16fc59fee0f1 commit
from Kay Sievers that removed the mount/umount uevents from the kernel.
Some older versions of HAL still depend on these events to detect when a
new device has been mounted.  These events are not correctly emitted,
and are broken by design, and so, should not be relied upon by any
future program.  Instead, the /proc/mounts file should be polled to
properly detect this kind of event.

A feature-removal-schedule.txt entry has been added, noting when this
interface will be removed from the kernel.

Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

4 files changed, 31 insertions, 3 deletions

diff --git a/Documentation/feature-removal-schedule.txt b/Documentation/feature-removal-schedule.txt
index b730d765b525..be5ae600f533 100644
--- a/Documentation/feature-removal-schedule.txt
+++ b/Documentation/feature-removal-schedule.txt
@@ -171,3 +171,12 @@ Why:	The ISA interface is faster and should be always available. The I2C
         probing is also known to cause trouble in at least one case (see
         bug #5889.)
 Who:    Jean Delvare <khali@linux-fr.org>
+
+---------------------------
+
+What:   mount/umount uevents
+When:   February 2007
+Why:    These events are not correct, and do not properly let userspace know
+        when a file system has been mounted or unmounted.  Userspace should
+        poll the /proc/mounts file instead to detect this properly.
+Who:    Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/fs/super.c b/fs/super.c
index 30294218fa63..e20b5580afd5 100644
--- a/fs/super.c
+++ b/fs/super.c
@@ -666,6 +666,16 @@ static int test_bdev_super(struct super_block *s, void *data)
         return (void *)s->s_bdev == data;
 }
 
+static void bdev_uevent(struct block_device *bdev, enum kobject_action action)
+{
+        if (bdev->bd_disk) {
+                if (bdev->bd_part)
+                        kobject_uevent(&bdev->bd_part->kobj, action);
+                else
+                        kobject_uevent(&bdev->bd_disk->kobj, action);
+        }
+}
+
 struct super_block *get_sb_bdev(struct file_system_type *fs_type,
         int flags, const char *dev_name, void *data,
         int (*fill_super)(struct super_block *, void *, int))
@@ -707,8 +717,10 @@ struct super_block *get_sb_bdev(struct file_system_type *fs_type,
                         up_write(&s->s_umount);
                         deactivate_super(s);
                         s = ERR_PTR(error);
-                } else
+                } else {
                         s->s_flags |= MS_ACTIVE;
+                        bdev_uevent(bdev, KOBJ_MOUNT);
+                }
         }
 
         return s;
@@ -724,6 +736,7 @@ void kill_block_super(struct super_block *sb)
 {
         struct block_device *bdev = sb->s_bdev;
 
+        bdev_uevent(bdev, KOBJ_UMOUNT);
         generic_shutdown_super(sb);
         sync_blockdev(bdev);
         close_bdev_excl(bdev);
diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index 2a8d8da70961..c374b5fa8d3b 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -41,8 +41,10 @@ enum kobject_action {
         KOBJ_ADD        = (__force kobject_action_t) 0x01,      /* exclusive to core */
         KOBJ_REMOVE     = (__force kobject_action_t) 0x02,      /* exclusive to core */
         KOBJ_CHANGE     = (__force kobject_action_t) 0x03,      /* device state change */
-        KOBJ_OFFLINE    = (__force kobject_action_t) 0x04,      /* device offline */
-        KOBJ_ONLINE     = (__force kobject_action_t) 0x05,      /* device online */
+        KOBJ_MOUNT      = (__force kobject_action_t) 0x04,      /* mount event for block devices (broken) */
+        KOBJ_UMOUNT     = (__force kobject_action_t) 0x05,      /* umount event for block devices (broken) */
+        KOBJ_OFFLINE    = (__force kobject_action_t) 0x06,      /* device offline */
+        KOBJ_ONLINE     = (__force kobject_action_t) 0x07,      /* device online */
 };
 
 struct kobject {
diff --git a/lib/kobject_uevent.c b/lib/kobject_uevent.c
index 1b1985c136ec..086a0c6e888e 100644
--- a/lib/kobject_uevent.c
+++ b/lib/kobject_uevent.c
@@ -38,6 +38,10 @@ static char *action_to_string(enum kobject_action action)
                 return "remove";
         case KOBJ_CHANGE:
                 return "change";
+        case KOBJ_MOUNT:
+                return "mount";
+        case KOBJ_UMOUNT:
+                return "umount";
         case KOBJ_OFFLINE:
                 return "offline";
         case KOBJ_ONLINE: