RE: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Mario.Limonciello]

> -Original Message-
> From: rjwyso...@gmail.com [mailto:rjwyso...@gmail.com] On Behalf Of Rafael J.
> Wysocki
> Sent: Friday, March 2, 2018 3:43 AM
> To: Limonciello, Mario <mario_limoncie...@dell.com>
> Cc: Andy Shevchenko <andy.shevche...@gmail.com>; Rafael J. Wysocki
> <r...@rjwysocki.net>; ACPI Devel Maling List <linux-a...@vger.kernel.org>; 
> Linux
> Kernel Mailing List <linux-kernel@vger.kernel.org>
> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
> friendly
> 
> On Wed, Feb 28, 2018 at 9:05 PM,  <mario.limoncie...@dell.com> wrote:
> >
> >
> >> -Original Message-
> >> From: Andy Shevchenko [mailto:andy.shevche...@gmail.com]
> >> Sent: Wednesday, February 28, 2018 12:11 PM
> >> To: Limonciello, Mario <mario_limoncie...@dell.com>
> >> Cc: Rafael J . Wysocki <r...@rjwysocki.net>; ACPI Devel Maling List  >> a...@vger.kernel.org>; LKML <linux-kernel@vger.kernel.org>
> >> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
> >> friendly
> >>
> >> On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
> >> <mario.limoncie...@dell.com> wrote:
> >> > Currently the only way to specify a hibernate offset for a swap
> >> > file is on the kernel command line.
> >> >
> >> > This makes some changes to improve:
> >> > 1) Add a new /sys/power/disk_offset that lets userspace specify
> >> > the offset and disk to use when initiating a hibernate cycle.
> >> >
> >> > 2) Adjust /sys/power/resume interpretation to also read in an
> >> > offset.
> >>
> >> Read is okay per se (not consistent though), showing is not.
> >> It might break an ABI.
> >
> > Right this is part of why I was proposing making a new attribute.
> >
> > The current RFC implementation I sent keeps the read output the
> > same for /sys/power/resume.
> 
> You also need to retain the write behavior of it.
> 
> A new attribute is fine if it helps, but the behavior of the existing
> one cannot change (both sides).

Thanks for your feedback, I'll adjust it as such.

RE: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Mario.Limonciello]

> -Original Message-
> From: rjwyso...@gmail.com [mailto:rjwyso...@gmail.com] On Behalf Of Rafael J.
> Wysocki
> Sent: Friday, March 2, 2018 3:43 AM
> To: Limonciello, Mario 
> Cc: Andy Shevchenko ; Rafael J. Wysocki
> ; ACPI Devel Maling List ; 
> Linux
> Kernel Mailing List 
> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
> friendly
> 
> On Wed, Feb 28, 2018 at 9:05 PM,   wrote:
> >
> >
> >> -Original Message-
> >> From: Andy Shevchenko [mailto:andy.shevche...@gmail.com]
> >> Sent: Wednesday, February 28, 2018 12:11 PM
> >> To: Limonciello, Mario 
> >> Cc: Rafael J . Wysocki ; ACPI Devel Maling List  >> a...@vger.kernel.org>; LKML 
> >> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
> >> friendly
> >>
> >> On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
> >>  wrote:
> >> > Currently the only way to specify a hibernate offset for a swap
> >> > file is on the kernel command line.
> >> >
> >> > This makes some changes to improve:
> >> > 1) Add a new /sys/power/disk_offset that lets userspace specify
> >> > the offset and disk to use when initiating a hibernate cycle.
> >> >
> >> > 2) Adjust /sys/power/resume interpretation to also read in an
> >> > offset.
> >>
> >> Read is okay per se (not consistent though), showing is not.
> >> It might break an ABI.
> >
> > Right this is part of why I was proposing making a new attribute.
> >
> > The current RFC implementation I sent keeps the read output the
> > same for /sys/power/resume.
> 
> You also need to retain the write behavior of it.
> 
> A new attribute is fine if it helps, but the behavior of the existing
> one cannot change (both sides).

Thanks for your feedback, I'll adjust it as such.

Re: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Rafael J. Wysocki]

On Wed, Feb 28, 2018 at 9:05 PM,  <mario.limoncie...@dell.com> wrote:
>
>
>> -Original Message-
>> From: Andy Shevchenko [mailto:andy.shevche...@gmail.com]
>> Sent: Wednesday, February 28, 2018 12:11 PM
>> To: Limonciello, Mario <mario_limoncie...@dell.com>
>> Cc: Rafael J . Wysocki <r...@rjwysocki.net>; ACPI Devel Maling List > a...@vger.kernel.org>; LKML <linux-kernel@vger.kernel.org>
>> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
>> friendly
>>
>> On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
>> <mario.limoncie...@dell.com> wrote:
>> > Currently the only way to specify a hibernate offset for a swap
>> > file is on the kernel command line.
>> >
>> > This makes some changes to improve:
>> > 1) Add a new /sys/power/disk_offset that lets userspace specify
>> > the offset and disk to use when initiating a hibernate cycle.
>> >
>> > 2) Adjust /sys/power/resume interpretation to also read in an
>> > offset.
>>
>> Read is okay per se (not consistent though), showing is not.
>> It might break an ABI.
>
> Right this is part of why I was proposing making a new attribute.
>
> The current RFC implementation I sent keeps the read output the
> same for /sys/power/resume.

You also need to retain the write behavior of it.

A new attribute is fine if it helps, but the behavior of the existing
one cannot change (both sides).

Re: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Rafael J. Wysocki]

On Wed, Feb 28, 2018 at 9:05 PM,   wrote:
>
>
>> -Original Message-
>> From: Andy Shevchenko [mailto:andy.shevche...@gmail.com]
>> Sent: Wednesday, February 28, 2018 12:11 PM
>> To: Limonciello, Mario 
>> Cc: Rafael J . Wysocki ; ACPI Devel Maling List > a...@vger.kernel.org>; LKML 
>> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
>> friendly
>>
>> On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
>>  wrote:
>> > Currently the only way to specify a hibernate offset for a swap
>> > file is on the kernel command line.
>> >
>> > This makes some changes to improve:
>> > 1) Add a new /sys/power/disk_offset that lets userspace specify
>> > the offset and disk to use when initiating a hibernate cycle.
>> >
>> > 2) Adjust /sys/power/resume interpretation to also read in an
>> > offset.
>>
>> Read is okay per se (not consistent though), showing is not.
>> It might break an ABI.
>
> Right this is part of why I was proposing making a new attribute.
>
> The current RFC implementation I sent keeps the read output the
> same for /sys/power/resume.

You also need to retain the write behavior of it.

A new attribute is fine if it helps, but the behavior of the existing
one cannot change (both sides).

RE: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Mario.Limonciello]

> -Original Message-
> From: Andy Shevchenko [mailto:andy.shevche...@gmail.com]
> Sent: Wednesday, February 28, 2018 12:11 PM
> To: Limonciello, Mario <mario_limoncie...@dell.com>
> Cc: Rafael J . Wysocki <r...@rjwysocki.net>; ACPI Devel Maling List  a...@vger.kernel.org>; LKML <linux-kernel@vger.kernel.org>
> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
> friendly
> 
> On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
> <mario.limoncie...@dell.com> wrote:
> > Currently the only way to specify a hibernate offset for a swap
> > file is on the kernel command line.
> >
> > This makes some changes to improve:
> > 1) Add a new /sys/power/disk_offset that lets userspace specify
> > the offset and disk to use when initiating a hibernate cycle.
> >
> > 2) Adjust /sys/power/resume interpretation to also read in an
> > offset.
> 
> Read is okay per se (not consistent though), showing is not.
> It might break an ABI.

Right this is part of why I was proposing making a new attribute.

The current RFC implementation I sent keeps the read output the
same for /sys/power/resume.

> 
> > Actually klibc's /bin/resume has supported passing a hibernate
> > offset in since 20695264e21dcbde309cd81f73cfe2cea42e779d.
> >
> > The kernel was just lobbing anything after the device specified
> > off the string.  Instead parse that and populate hibernate offset
> > with it.
> 
> > An alternative to introducing a new sysfs parameter may be to document
> > setting these values via /sys/power/resume.  If the wrong signature is found
> > on the swapfile/swap partition by the kernel it does show an error
> > but it updates the values and they'll work when actually invoked later.
> 
> Don't you need to document new node?

Yes, I wanted to get feedback before I reworked documentation and that's
why I implemented both approaches right now.

Maybe both even make sense.
When I resubmit as a patch I'll make sure documentation is updated.

> 
> > +static int parse_device_input(const char *buf, size_t n)
> >  {
> > +   unsigned long long offset;
> > dev_t res;
> > int len = n;
> > char *name;
> > +   char *last;
> >
> > if (len && buf[len-1] == '\n')
> > len--;
> 
> I'm not sure first part even needed, but okay, it's in original code.
> 
> > name = kstrndup(buf, len, GFP_KERNEL);
> > if (!name)
> > return -ENOMEM;
> 
> Side notes.
> This whole dance b/c of high probability of '\n' at the end which
> breaks _some_ kernel parsers.
> It might make sense to do a wrapper and call the guts of this function
> with or without memory allocation depending on presence of '\n'.
> 

OK.

> > -
> 
> This is not needed to be removed.
> 
> > +   last = strrchr(name, ':');
> 
> > +   printk("%lu %s %s %d", last-name, name, last, len);
> 
> Ouch. I guess it's only for RFC.

Yes I was having problems originally and it was debug, it won't
be there when submitted for application.

> 
> > +   if (last != NULL &&
> 
> > +   (last-name) != len-1 &&
> 
> > +   sscanf(last+1, "%llu", ) == 1)
> 
> This is effectively
> 
> if (last && *(last+1)) {
>   int ret = kstrtoull(..._resume_block...);
>   if (ret)
>...warn?..
> }
> 
> ?

I'll have to look more closely, but if this simplification
works I'll switch over.

> 
> > +swsusp_resume_block = offset;
> 
> > +   swsusp_resume_device = res;
> > +
> 
> > +   return 1;
> 
> ???
> Why not traditional 0?
> 
> > +}
> 
> > @@ -1125,7 +1161,6 @@ static int __init pm_disk_init(void)
> >
> >  core_initcall(pm_disk_init);
> >
> > -
> 
> This doesn't belong to the change.
> 
> --
> With Best Regards,
> Andy Shevchenko

RE: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Mario.Limonciello]

> -Original Message-
> From: Andy Shevchenko [mailto:andy.shevche...@gmail.com]
> Sent: Wednesday, February 28, 2018 12:11 PM
> To: Limonciello, Mario 
> Cc: Rafael J . Wysocki ; ACPI Devel Maling List  a...@vger.kernel.org>; LKML 
> Subject: Re: [RFC] power/hibernate: Make passing hibernate offsets more 
> friendly
> 
> On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
>  wrote:
> > Currently the only way to specify a hibernate offset for a swap
> > file is on the kernel command line.
> >
> > This makes some changes to improve:
> > 1) Add a new /sys/power/disk_offset that lets userspace specify
> > the offset and disk to use when initiating a hibernate cycle.
> >
> > 2) Adjust /sys/power/resume interpretation to also read in an
> > offset.
> 
> Read is okay per se (not consistent though), showing is not.
> It might break an ABI.

Right this is part of why I was proposing making a new attribute.

The current RFC implementation I sent keeps the read output the
same for /sys/power/resume.

> 
> > Actually klibc's /bin/resume has supported passing a hibernate
> > offset in since 20695264e21dcbde309cd81f73cfe2cea42e779d.
> >
> > The kernel was just lobbing anything after the device specified
> > off the string.  Instead parse that and populate hibernate offset
> > with it.
> 
> > An alternative to introducing a new sysfs parameter may be to document
> > setting these values via /sys/power/resume.  If the wrong signature is found
> > on the swapfile/swap partition by the kernel it does show an error
> > but it updates the values and they'll work when actually invoked later.
> 
> Don't you need to document new node?

Yes, I wanted to get feedback before I reworked documentation and that's
why I implemented both approaches right now.

Maybe both even make sense.
When I resubmit as a patch I'll make sure documentation is updated.

> 
> > +static int parse_device_input(const char *buf, size_t n)
> >  {
> > +   unsigned long long offset;
> > dev_t res;
> > int len = n;
> > char *name;
> > +   char *last;
> >
> > if (len && buf[len-1] == '\n')
> > len--;
> 
> I'm not sure first part even needed, but okay, it's in original code.
> 
> > name = kstrndup(buf, len, GFP_KERNEL);
> > if (!name)
> > return -ENOMEM;
> 
> Side notes.
> This whole dance b/c of high probability of '\n' at the end which
> breaks _some_ kernel parsers.
> It might make sense to do a wrapper and call the guts of this function
> with or without memory allocation depending on presence of '\n'.
> 

OK.

> > -
> 
> This is not needed to be removed.
> 
> > +   last = strrchr(name, ':');
> 
> > +   printk("%lu %s %s %d", last-name, name, last, len);
> 
> Ouch. I guess it's only for RFC.

Yes I was having problems originally and it was debug, it won't
be there when submitted for application.

> 
> > +   if (last != NULL &&
> 
> > +   (last-name) != len-1 &&
> 
> > +   sscanf(last+1, "%llu", ) == 1)
> 
> This is effectively
> 
> if (last && *(last+1)) {
>   int ret = kstrtoull(..._resume_block...);
>   if (ret)
>...warn?..
> }
> 
> ?

I'll have to look more closely, but if this simplification
works I'll switch over.

> 
> > +swsusp_resume_block = offset;
> 
> > +   swsusp_resume_device = res;
> > +
> 
> > +   return 1;
> 
> ???
> Why not traditional 0?
> 
> > +}
> 
> > @@ -1125,7 +1161,6 @@ static int __init pm_disk_init(void)
> >
> >  core_initcall(pm_disk_init);
> >
> > -
> 
> This doesn't belong to the change.
> 
> --
> With Best Regards,
> Andy Shevchenko

Re: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Andy Shevchenko]

On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
 wrote:
> Currently the only way to specify a hibernate offset for a swap
> file is on the kernel command line.
>
> This makes some changes to improve:
> 1) Add a new /sys/power/disk_offset that lets userspace specify
> the offset and disk to use when initiating a hibernate cycle.
>
> 2) Adjust /sys/power/resume interpretation to also read in an
> offset.

Read is okay per se (not consistent though), showing is not.
It might break an ABI.

> Actually klibc's /bin/resume has supported passing a hibernate
> offset in since 20695264e21dcbde309cd81f73cfe2cea42e779d.
>
> The kernel was just lobbing anything after the device specified
> off the string.  Instead parse that and populate hibernate offset
> with it.

> An alternative to introducing a new sysfs parameter may be to document
> setting these values via /sys/power/resume.  If the wrong signature is found
> on the swapfile/swap partition by the kernel it does show an error
> but it updates the values and they'll work when actually invoked later.

Don't you need to document new node?

> +static int parse_device_input(const char *buf, size_t n)
>  {
> +   unsigned long long offset;
> dev_t res;
> int len = n;
> char *name;
> +   char *last;
>
> if (len && buf[len-1] == '\n')
> len--;

I'm not sure first part even needed, but okay, it's in original code.

> name = kstrndup(buf, len, GFP_KERNEL);
> if (!name)
> return -ENOMEM;

Side notes.
This whole dance b/c of high probability of '\n' at the end which
breaks _some_ kernel parsers.
It might make sense to do a wrapper and call the guts of this function
with or without memory allocation depending on presence of '\n'.

> -

This is not needed to be removed.

> +   last = strrchr(name, ':');

> +   printk("%lu %s %s %d", last-name, name, last, len);

Ouch. I guess it's only for RFC.

> +   if (last != NULL &&

> +   (last-name) != len-1 &&

> +   sscanf(last+1, "%llu", ) == 1)

This is effectively

if (last && *(last+1)) {
  int ret = kstrtoull(..._resume_block...);
  if (ret)
   ...warn?..
}

?

> +swsusp_resume_block = offset;

> +   swsusp_resume_device = res;
> +

> +   return 1;

???
Why not traditional 0?

> +}

> @@ -1125,7 +1161,6 @@ static int __init pm_disk_init(void)
>
>  core_initcall(pm_disk_init);
>
> -

This doesn't belong to the change.

-- 
With Best Regards,
Andy Shevchenko

Re: [RFC] power/hibernate: Make passing hibernate offsets more friendly

[Andy Shevchenko]

On Wed, Feb 28, 2018 at 7:43 PM, Mario Limonciello
 wrote:
> Currently the only way to specify a hibernate offset for a swap
> file is on the kernel command line.
>
> This makes some changes to improve:
> 1) Add a new /sys/power/disk_offset that lets userspace specify
> the offset and disk to use when initiating a hibernate cycle.
>
> 2) Adjust /sys/power/resume interpretation to also read in an
> offset.

Read is okay per se (not consistent though), showing is not.
It might break an ABI.

> Actually klibc's /bin/resume has supported passing a hibernate
> offset in since 20695264e21dcbde309cd81f73cfe2cea42e779d.
>
> The kernel was just lobbing anything after the device specified
> off the string.  Instead parse that and populate hibernate offset
> with it.

> An alternative to introducing a new sysfs parameter may be to document
> setting these values via /sys/power/resume.  If the wrong signature is found
> on the swapfile/swap partition by the kernel it does show an error
> but it updates the values and they'll work when actually invoked later.

Don't you need to document new node?

> +static int parse_device_input(const char *buf, size_t n)
>  {
> +   unsigned long long offset;
> dev_t res;
> int len = n;
> char *name;
> +   char *last;
>
> if (len && buf[len-1] == '\n')
> len--;

I'm not sure first part even needed, but okay, it's in original code.

> name = kstrndup(buf, len, GFP_KERNEL);
> if (!name)
> return -ENOMEM;

Side notes.
This whole dance b/c of high probability of '\n' at the end which
breaks _some_ kernel parsers.
It might make sense to do a wrapper and call the guts of this function
with or without memory allocation depending on presence of '\n'.

> -

This is not needed to be removed.

> +   last = strrchr(name, ':');

> +   printk("%lu %s %s %d", last-name, name, last, len);

Ouch. I guess it's only for RFC.

> +   if (last != NULL &&

> +   (last-name) != len-1 &&

> +   sscanf(last+1, "%llu", ) == 1)

This is effectively

if (last && *(last+1)) {
  int ret = kstrtoull(..._resume_block...);
  if (ret)
   ...warn?..
}

?

> +swsusp_resume_block = offset;

> +   swsusp_resume_device = res;
> +

> +   return 1;

???
Why not traditional 0?

> +}

> @@ -1125,7 +1161,6 @@ static int __init pm_disk_init(void)
>
>  core_initcall(pm_disk_init);
>
> -

This doesn't belong to the change.

-- 
With Best Regards,
Andy Shevchenko

[RFC] power/hibernate: Make passing hibernate offsets more friendly

[Mario Limonciello]

Currently the only way to specify a hibernate offset for a swap
file is on the kernel command line.

This makes some changes to improve:
1) Add a new /sys/power/disk_offset that lets userspace specify
the offset and disk to use when initiating a hibernate cycle.

2) Adjust /sys/power/resume interpretation to also read in an
offset.

Actually klibc's /bin/resume has supported passing a hibernate
offset in since 20695264e21dcbde309cd81f73cfe2cea42e779d.

The kernel was just lobbing anything after the device specified
off the string.  Instead parse that and populate hibernate offset
with it.

Signed-off-by: Mario Limonciello 
---
An alternative to introducing a new sysfs parameter may be to document
setting these values via /sys/power/resume.  If the wrong signature is found
on the swapfile/swap partition by the kernel it does show an error
but it updates the values and they'll work when actually invoked later.

In that case it may make sense to adjust that error and make it level
info and explain the situation.

 kernel/power/hibernate.c | 59 ++--
 1 file changed, 47 insertions(+), 12 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index a5c36e9..f606ed6 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -1025,33 +1025,68 @@ static ssize_t disk_store(struct kobject *kobj, struct 
kobj_attribute *attr,
 
 power_attr(disk);
 
-static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
-  char *buf)
-{
-   return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
-  MINOR(swsusp_resume_device));
-}
-
-static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
-   const char *buf, size_t n)
+static int parse_device_input(const char *buf, size_t n)
 {
+   unsigned long long offset;
dev_t res;
int len = n;
char *name;
+   char *last;
 
if (len && buf[len-1] == '\n')
len--;
name = kstrndup(buf, len, GFP_KERNEL);
if (!name)
return -ENOMEM;
-
+   last = strrchr(name, ':');
+   printk("%lu %s %s %d", last-name, name, last, len);
+   if (last != NULL &&
+   (last-name) != len-1 &&
+   sscanf(last+1, "%llu", ) == 1)
+swsusp_resume_block = offset;
res = name_to_dev_t(name);
kfree(name);
if (!res)
return -EINVAL;
+   swsusp_resume_device = res;
+
+   return 1;
+}
+
+static ssize_t disk_offset_show(struct kobject *kobj, struct kobj_attribute 
*attr,
+   char *buf)
+{
+   return sprintf(buf,"%d:%d:%lu\n", MAJOR(swsusp_resume_device),
+  MINOR(swsusp_resume_device), swsusp_resume_block);
+}
+
+static ssize_t disk_offset_store(struct kobject *kobj, struct kobj_attribute 
*attr,
+const char *buf, size_t n)
+{
+   ssize_t rc = parse_device_input(buf, n);
+   if (rc < 0)
+   return rc;
+
+   return n;
+}
+
+power_attr(disk_offset);
+
+static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
+  char *buf)
+{
+   return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
+  MINOR(swsusp_resume_device));
+}
+
+static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
+   const char *buf, size_t n)
+{
+   ssize_t rc = parse_device_input(buf, n);
+   if (rc < 0)
+   return rc;
 
lock_system_sleep();
-   swsusp_resume_device = res;
unlock_system_sleep();
pr_info("Starting manual resume from disk\n");
noresume = 0;
@@ -1106,6 +1141,7 @@ power_attr(reserved_size);
 
 static struct attribute * g[] = {
_attr.attr,
+   _offset_attr.attr,
_attr.attr,
_size_attr.attr,
_size_attr.attr,
@@ -1125,7 +1161,6 @@ static int __init pm_disk_init(void)
 
 core_initcall(pm_disk_init);
 
-
 static int __init resume_setup(char *str)
 {
if (noresume)
-- 
2.7.4

[RFC] power/hibernate: Make passing hibernate offsets more friendly

[Mario Limonciello]

Currently the only way to specify a hibernate offset for a swap
file is on the kernel command line.

This makes some changes to improve:
1) Add a new /sys/power/disk_offset that lets userspace specify
the offset and disk to use when initiating a hibernate cycle.

2) Adjust /sys/power/resume interpretation to also read in an
offset.

Actually klibc's /bin/resume has supported passing a hibernate
offset in since 20695264e21dcbde309cd81f73cfe2cea42e779d.

The kernel was just lobbing anything after the device specified
off the string.  Instead parse that and populate hibernate offset
with it.

Signed-off-by: Mario Limonciello 
---
An alternative to introducing a new sysfs parameter may be to document
setting these values via /sys/power/resume.  If the wrong signature is found
on the swapfile/swap partition by the kernel it does show an error
but it updates the values and they'll work when actually invoked later.

In that case it may make sense to adjust that error and make it level
info and explain the situation.

 kernel/power/hibernate.c | 59 ++--
 1 file changed, 47 insertions(+), 12 deletions(-)

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index a5c36e9..f606ed6 100644
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -1025,33 +1025,68 @@ static ssize_t disk_store(struct kobject *kobj, struct 
kobj_attribute *attr,
 
 power_attr(disk);
 
-static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
-  char *buf)
-{
-   return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
-  MINOR(swsusp_resume_device));
-}
-
-static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
-   const char *buf, size_t n)
+static int parse_device_input(const char *buf, size_t n)
 {
+   unsigned long long offset;
dev_t res;
int len = n;
char *name;
+   char *last;
 
if (len && buf[len-1] == '\n')
len--;
name = kstrndup(buf, len, GFP_KERNEL);
if (!name)
return -ENOMEM;
-
+   last = strrchr(name, ':');
+   printk("%lu %s %s %d", last-name, name, last, len);
+   if (last != NULL &&
+   (last-name) != len-1 &&
+   sscanf(last+1, "%llu", ) == 1)
+swsusp_resume_block = offset;
res = name_to_dev_t(name);
kfree(name);
if (!res)
return -EINVAL;
+   swsusp_resume_device = res;
+
+   return 1;
+}
+
+static ssize_t disk_offset_show(struct kobject *kobj, struct kobj_attribute 
*attr,
+   char *buf)
+{
+   return sprintf(buf,"%d:%d:%lu\n", MAJOR(swsusp_resume_device),
+  MINOR(swsusp_resume_device), swsusp_resume_block);
+}
+
+static ssize_t disk_offset_store(struct kobject *kobj, struct kobj_attribute 
*attr,
+const char *buf, size_t n)
+{
+   ssize_t rc = parse_device_input(buf, n);
+   if (rc < 0)
+   return rc;
+
+   return n;
+}
+
+power_attr(disk_offset);
+
+static ssize_t resume_show(struct kobject *kobj, struct kobj_attribute *attr,
+  char *buf)
+{
+   return sprintf(buf,"%d:%d\n", MAJOR(swsusp_resume_device),
+  MINOR(swsusp_resume_device));
+}
+
+static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
+   const char *buf, size_t n)
+{
+   ssize_t rc = parse_device_input(buf, n);
+   if (rc < 0)
+   return rc;
 
lock_system_sleep();
-   swsusp_resume_device = res;
unlock_system_sleep();
pr_info("Starting manual resume from disk\n");
noresume = 0;
@@ -1106,6 +1141,7 @@ power_attr(reserved_size);
 
 static struct attribute * g[] = {
_attr.attr,
+   _offset_attr.attr,
_attr.attr,
_size_attr.attr,
_size_attr.attr,
@@ -1125,7 +1161,6 @@ static int __init pm_disk_init(void)
 
 core_initcall(pm_disk_init);
 
-
 static int __init resume_setup(char *str)
 {
if (noresume)
-- 
2.7.4