Commit 32c356d7 authored Aug 20, 2008 by James Bottomley

[SCSI] fix removable device inability to detect disk changes



On Tue, 12 Aug 2008 15:08:14 +0200
Giuliano Pochini <pochini@shiny.it> wrote:

> Fujitsu magneto-optical drive, Adaptec 29160 and
> Linux Jay 2.6.26 #7 SMP Sun Aug 10 18:34:22 CEST 2008 ppc 7455, altivec supported PowerMac3,6 GNU/Linux
>
> When I insert a disk and I mount it, scsi_test_unit_ready() is called and
> the do-while loop gets sshdr->sense_key == UNIT_ATTENTION in the first
> cycle and 0 in the second one. So the if below misses the UNIT_ATTENTION
> and sdev->changed = 1 is not executed. At this point bad things can
> happen... I'm not sure how to fix this. Any clue ?

The problem is essentially caused by us eating UNIT_ATTENTION
conditions in scsi_test_unit_ready().  Fix by updating the ->changed
flag when this happens if the media is removable.

[pochini@shiny.it: updates to tidy up patch]
Signed-off-by: Giuliano Pochini <pochini@shiny.it>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

parent 26e9a397

drivers/scsi/scsi_lib.c

+10 −11

Original line number	Diff line number	Diff line
		@@ -2105,23 +2105,22 @@ scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
		do {
		result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
		timeout, retries);
		} while ((driver_byte(result) & DRIVER_SENSE) &&
		sshdr && sshdr->sense_key == UNIT_ATTENTION &&
		--retries);
		if (sdev->removable && scsi_sense_valid(sshdr) &&
		sshdr->sense_key == UNIT_ATTENTION)
		sdev->changed = 1;
		} while (scsi_sense_valid(sshdr) &&
		sshdr->sense_key == UNIT_ATTENTION && --retries);

		if (!sshdr)
		/* could not allocate sense buffer, so can't process it */
		return result;

		if ((driver_byte(result) & DRIVER_SENSE) && sdev->removable) {

		if ((scsi_sense_valid(sshdr)) &&
		((sshdr->sense_key == UNIT_ATTENTION) \|\|
		(sshdr->sense_key == NOT_READY))) {
		if (sdev->removable && scsi_sense_valid(sshdr) &&
		(sshdr->sense_key == UNIT_ATTENTION \|\|
		sshdr->sense_key == NOT_READY)) {
		sdev->changed = 1;
		result = 0;
		}
		}
		if (!sshdr_external)
		kfree(sshdr);
		return result;