2.6.1: media change check fails for busy unplugged device

[Andrey Borzenkov]

If we unplug busy device (consider mounted USB stick) media change check 
always returns true (no media change happened). It happens because

- device state is set to SDEV_DEL and scsi_prep_fn silently kills any request 
including TEST_UNIT_READY sent by sd_media_changed without propagating any 
information back to caller

- sdev->online still remains TRUE

so nothing ever tells sd_media_changed that device is gone.

this effectively prevents supermount from noticing that it needs remount 
subfs.

What is the right place to catch those deleted device? For now I add this as 
part of supermount patch, but it looks too ugly (and in the wrong place):

--- linux-2.6.1/drivers/scsi/sd.c       29 Dec 2003 17:20:12 -0000
+++ linux-2.6.1/drivers/scsi/sd.c       18 Jan 2004 18:20:54 -0000
@@ -620,6 +622,16 @@ static int sd_media_changed(struct gendi
                 goto not_present;

        /*
+        * FIXME HACK
+        * busy device that is unplugged is SDEV_DEL but online and ioctl
+        * does not return any error. Oh well, it is likely layering
+        * violation but for now it enables media checks for supermount
+        */
+
+       if (sdp->sdev_state == SDEV_DEL)
+               goto not_present;
+
+       /*
         * For removable scsi disk we have to recognise the presence
         * of a disk in the drive. This is kept in the struct scsi_disk
         * struct and tested at open !  Daniel Roche (dan@xxxxxxxxx)
 
TIA

-andrey

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