[PATCH] dm: prevent removal if open

If you misuse the device-mapper interface (or there's a bug in your userspace
tools) it's possible to end up with 'unlinked' mapped devices that cannot be
removed until you reboot (along with uninterruptible processes).

This patch prevents you from removing a device that is still open.

It introduces dm_lock_for_deletion() which is called when a device is about to
be removed to ensure that nothing has it open and nothing further can open it.
 It uses a private open_count for this which also lets us remove one of the
problematic bdget_disk() calls elsewhere.

Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/linux/dm-ioctl.h b/include/linux/dm-ioctl.h
index c67c6786612a..9623bb625090 100644
--- a/include/linux/dm-ioctl.h
+++ b/include/linux/dm-ioctl.h
@@ -285,9 +285,9 @@ typedef char ioctl_struct[308];
 #define DM_DEV_SET_GEOMETRY     _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
 
 #define DM_VERSION_MAJOR        4
-#define DM_VERSION_MINOR        6
+#define DM_VERSION_MINOR        7
 #define DM_VERSION_PATCHLEVEL   0
-#define DM_VERSION_EXTRA        "-ioctl (2006-02-17)"
+#define DM_VERSION_EXTRA        "-ioctl (2006-06-24)"
 
 /* Status bits */
 #define DM_READONLY_FLAG        (1 << 0) /* In/Out */
@@ -314,7 +314,7 @@ typedef char ioctl_struct[308];
 #define DM_BUFFER_FULL_FLAG     (1 << 8) /* Out */
 
 /*
- * Set this to improve performance when you aren't going to use open_count.
+ * This flag is now ignored.
  */
 #define DM_SKIP_BDGET_FLAG      (1 << 9) /* In */