Re: [PATCH] 2.6.6 swsusp.c: allow device aliasing

From: Pavel Machek
Date: Mon May 10 2004 - 12:12:22 EST


> I'm using devfs. (I'm using /dev/hda7 for swsusp.) So, cat
> /proc/swaps shows my swap device as:
> Filename Type Size Used Priority
> /dev/ide/host0/bus0/target0/lun0/part7 partition 498920 0 -1
> whereas I specify "resume=/dev/hda7" as a boot parameter. Upon
> suspend, swsusp can't find a swap device exactly named "/dev/hda7" and
> hence thinks there is no swapspace.
> The problem is that:
> 1) Upon suspend, kernel/power/swsusp.c compares the devices names
> "/dev/hda7" and "/dev/ide/.../part7" and they don't match. So
> swsusp refuses to suspend to the swap partition. Changing the
> boot parameter to "resume=/dev/ide/host0/bus0/target0/lun0/part7"
> solves this problem, BUT:
> 2) Upon resume, kernel/power/swsusp.c doesn't understand what a device
> "/dev/ide/host0/bus0/target0/lun0/part7" is. It only knows what
> "/dev/hda7". So, I have to set "resume=/dev/hda7" for resume to
> work. But this would create problem (1).
> So, I can't get both suspend and resume to work! :(
> Why did it work in pre-2.6.6? Because that check in swsusp.c in pre
> 2.6.6 didn't really check if the device is correct upon suspend. The
> suspend code only writes the suspend/resume data to the FIRST swap
> device. 2.6.6 has corrected this bug, but can't equate "/dev/hda7" to
> "/dev/ide/host0/bus0/target0/lun0/part7", although the two refer to
> the same device.
> The following patch (against 2.6.6) fixes this problem in the suspend
> code. It will check whether both the swap device and the "resume="
> parameter refer to a block device with the same (major,minor) number.
> If so, the swap device is taken to be the one specified for swsusp to
> use. So, aliasing of devices is support. This means I must say
> "resume=/dev/hda7" and not
> "resume=/dev/ide/host0/bus0/target0/lun0/part7". If, however, the
> specified swap devices are (swap) files rather block devices, it only
> does a filename comparison. (Does swsusp support swap files? If so,
> should we also support file aliasing? How?)

No, swsusp only supports swap devices. That means that you probably
should kill d_path and name handling; that will slean the code up as

Oh and please

> --- linux-2.6.6-official/kernel/power/swsusp.c 2004/05/10 14:11:17 1.1
> +++ linux-2.6.6-swsusp-dev-aliasing/kernel/power/swsusp.c 2004/05/10 16:11:41 1.3
> @@ -215,47 +215,67 @@
> else if ((!memcmp("SWAPSPACE2",cur->swh.magic.magic,10)))
> memcpy(cur->swh.magic.magic,"S2SUSP....",10);
> else panic("\nSwapspace is not swapspace (%.10s)\n", cur->swh.magic.magic);
> cur-> = prev; /* prev is the first/last swap page of the resume area */
> /* lies *no more* in last 4/8 bytes of magic */
> }
> rw_swap_page_sync(WRITE, entry, page);
> __free_page(page);
> }
> +static int is_resume_file(const struct swap_info_struct *swap_info) {

Newline needed before {.

Otherwise it looks good. Can you submit fixed patch? Thanks,
Horseback riding is like software...
...vgf orggre jura vgf serr.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at
Please read the FAQ at