[PATCH 1/2] UBI: Implement UBI_METAONLY

[PATCH 1/2] UBI: Implement UBI_METAONLY

[Richard Weinberger]

UBI_METAONLY is a new open mode for UBI volumes, it indicates
that only meta data is being changed.
Meta data in terms of UBI volumes means data which is stored in the
UBI volume table but not on the volume itself.
While it does not interfere with UBI_READONLY and UBI_READWRITE
it is not allowed to use UBI_METAONLY together with UBI_EXCLUSIVE.

Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: Andrew Murray <amurray@embedded-bits.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 drivers/mtd/ubi/cdev.c  |  8 +++++---
 drivers/mtd/ubi/kapi.c  | 15 +++++++++++++--
 drivers/mtd/ubi/ubi.h   |  5 ++++-
 include/linux/mtd/ubi.h |  4 +++-
 4 files changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 59de69a..5f01edd 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -60,13 +60,13 @@ static int get_exclusive(struct ubi_volume_desc *desc)
 	struct ubi_volume *vol = desc->vol;
 
 	spin_lock(&vol->ubi->volumes_lock);
-	users = vol->readers + vol->writers + vol->exclusive;
+	users = vol->readers + vol->writers + vol->exclusive + vol->metaonly;
 	ubi_assert(users > 0);
 	if (users > 1) {
 		ubi_err("%d users for volume %d", users, vol->vol_id);
 		err = -EBUSY;
 	} else {
-		vol->readers = vol->writers = 0;
+		vol->readers = vol->writers = vol->metaonly = 0;
 		vol->exclusive = 1;
 		err = desc->mode;
 		desc->mode = UBI_EXCLUSIVE;
@@ -86,13 +86,15 @@ static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
 	struct ubi_volume *vol = desc->vol;
 
 	spin_lock(&vol->ubi->volumes_lock);
-	ubi_assert(vol->readers == 0 && vol->writers == 0);
+	ubi_assert(vol->readers == 0 && vol->writers == 0 && vol->metaonly == 0);
 	ubi_assert(vol->exclusive == 1 && desc->mode == UBI_EXCLUSIVE);
 	vol->exclusive = 0;
 	if (mode == UBI_READONLY)
 		vol->readers = 1;
 	else if (mode == UBI_READWRITE)
 		vol->writers = 1;
+	else if (mode == UBI_METAONLY)
+		vol->metaonly = 1;
 	else
 		vol->exclusive = 1;
 	spin_unlock(&vol->ubi->volumes_lock);
diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
index 3aac1ac..8599690 100644
--- a/drivers/mtd/ubi/kapi.c
+++ b/drivers/mtd/ubi/kapi.c
@@ -137,7 +137,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 		return ERR_PTR(-EINVAL);
 
 	if (mode != UBI_READONLY && mode != UBI_READWRITE &&
-	    mode != UBI_EXCLUSIVE)
+	    mode != UBI_EXCLUSIVE && mode != UBI_METAONLY)
 		return ERR_PTR(-EINVAL);
 
 	/*
@@ -182,10 +182,17 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 		break;
 
 	case UBI_EXCLUSIVE:
-		if (vol->exclusive || vol->writers || vol->readers)
+		if (vol->exclusive || vol->writers || vol->readers ||
+		    vol->metaonly)
 			goto out_unlock;
 		vol->exclusive = 1;
 		break;
+
+	case UBI_METAONLY:
+		if (vol->metaonly || vol->exclusive)
+			goto out_unlock;
+		vol->metaonly = 1;
+		break;
 	}
 	get_device(&vol->dev);
 	vol->ref_count += 1;
@@ -343,6 +350,10 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
 		break;
 	case UBI_EXCLUSIVE:
 		vol->exclusive = 0;
+		break;
+	case UBI_METAONLY:
+		vol->metaonly = 0;
+		break;
 	}
 	vol->ref_count -= 1;
 	spin_unlock(&ubi->volumes_lock);
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index 320fc38..c991a09 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -260,6 +260,7 @@ struct ubi_fm_pool {
  * @readers: number of users holding this volume in read-only mode
  * @writers: number of users holding this volume in read-write mode
  * @exclusive: whether somebody holds this volume in exclusive mode
+ * @metaonly: whether somebody is altering only meta data of this volume
  *
  * @reserved_pebs: how many physical eraseblocks are reserved for this volume
  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
@@ -308,6 +309,7 @@ struct ubi_volume {
 	int readers;
 	int writers;
 	int exclusive;
+	int metaonly;
 
 	int reserved_pebs;
 	int vol_type;
@@ -389,7 +391,8 @@ struct ubi_debug_info {
  * @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,
  *                @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
  *                @vol->readers, @vol->writers, @vol->exclusive,
- *                @vol->ref_count, @vol->mapping and @vol->eba_tbl.
+ *                @vol->metaonly, @vol->ref_count, @vol->mapping and
+ *                @vol->eba_tbl.
  * @ref_count: count of references on the UBI device
  * @image_seq: image sequence number recorded on EC headers
  *
diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h
index c3918a0..82b693f 100644
--- a/include/linux/mtd/ubi.h
+++ b/include/linux/mtd/ubi.h
@@ -34,11 +34,13 @@
  * UBI_READONLY: read-only mode
  * UBI_READWRITE: read-write mode
  * UBI_EXCLUSIVE: exclusive mode
+ * UBI_METAONLY: modify voulme meta data only
  */
 enum {
 	UBI_READONLY = 1,
 	UBI_READWRITE,
-	UBI_EXCLUSIVE
+	UBI_EXCLUSIVE,
+	UBI_METAONLY
 };
 
 /**
-- 
1.8.4.5

[PATCH 2/2] UBI: rename_volumes: Use UBI_METAONLY

[Richard Weinberger]

By using UBI_METAONLY in rename_volumes() it is now possible to rename
an UBI volume atomically while it is mounted.
This is useful for firmware upgrades.

Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: Andrew Murray <amurray@embedded-bits.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 drivers/mtd/ubi/cdev.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 5f01edd..fcdf7b9 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -735,7 +735,7 @@ static int rename_volumes(struct ubi_device *ubi,
 			goto out_free;
 		}
 
-		re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_READWRITE);
+		re->desc = ubi_open_volume(ubi->ubi_num, vol_id, UBI_METAONLY);
 		if (IS_ERR(re->desc)) {
 			err = PTR_ERR(re->desc);
 			ubi_err("cannot open volume %d, error %d", vol_id, err);
-- 
1.8.4.5

Re: [PATCH 1/2] UBI: Implement UBI_METAONLY

[Andrew Murray]

On 29 October 2014 14:52, Richard Weinberger <richard@nod.at> wrote:
> diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h
> index c3918a0..82b693f 100644
> --- a/include/linux/mtd/ubi.h
> +++ b/include/linux/mtd/ubi.h
> @@ -34,11 +34,13 @@
>   * UBI_READONLY: read-only mode
>   * UBI_READWRITE: read-write mode
>   * UBI_EXCLUSIVE: exclusive mode
> + * UBI_METAONLY: modify voulme meta data only

Typo - s/voulme/volume/g

>   */
>  enum {
>         UBI_READONLY = 1,
>         UBI_READWRITE,
> -       UBI_EXCLUSIVE
> +       UBI_EXCLUSIVE,
> +       UBI_METAONLY
>  };
>

Also you may want to add something similar to this:

--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -339,7 +339,7 @@ struct ubi_volume {
 /**
  * struct ubi_volume_desc - UBI volume descriptor returned when it is opened.
  * @vol: reference to the corresponding volume description object
- * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, or %UBI_EXCLUSIVE)
+ * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, %UBI_EXCLUSIVE or
%UBI_METAONLY)
  */
 struct ubi_volume_desc {
        struct ubi_volume *vol;

There is also a similar mention in gluebi.c: 'readers/writes/exclusive'.

Thanks,

Andrew Murray

Re: [PATCH 1/2] UBI: Implement UBI_METAONLY

[Richard Weinberger]

Am 29.10.2014 um 21:11 schrieb Andrew Murray:
> On 29 October 2014 14:52, Richard Weinberger <richard@nod.at> wrote:
>> diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h
>> index c3918a0..82b693f 100644
>> --- a/include/linux/mtd/ubi.h
>> +++ b/include/linux/mtd/ubi.h
>> @@ -34,11 +34,13 @@
>>   * UBI_READONLY: read-only mode
>>   * UBI_READWRITE: read-write mode
>>   * UBI_EXCLUSIVE: exclusive mode
>> + * UBI_METAONLY: modify voulme meta data only
> 
> Typo - s/voulme/volume/g

Thanks. :)

>>   */
>>  enum {
>>         UBI_READONLY = 1,
>>         UBI_READWRITE,
>> -       UBI_EXCLUSIVE
>> +       UBI_EXCLUSIVE,
>> +       UBI_METAONLY
>>  };
>>
> 
> Also you may want to add something similar to this:
> 
> --- a/drivers/mtd/ubi/ubi.h
> +++ b/drivers/mtd/ubi/ubi.h
> @@ -339,7 +339,7 @@ struct ubi_volume {
>  /**
>   * struct ubi_volume_desc - UBI volume descriptor returned when it is opened.
>   * @vol: reference to the corresponding volume description object
> - * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, or %UBI_EXCLUSIVE)
> + * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, %UBI_EXCLUSIVE or
> %UBI_METAONLY)
>   */
>  struct ubi_volume_desc {
>         struct ubi_volume *vol;
> 
> There is also a similar mention in gluebi.c: 'readers/writes/exclusive'.

Please send a patch for that. :)

Thanks,
//richard

Re: [PATCH 1/2] UBI: Implement UBI_METAONLY

[Andrew Murray]

On 29 October 2014 20:20, Richard Weinberger <richard@nod.at> wrote:
> Am 29.10.2014 um 21:11 schrieb Andrew Murray:
>> On 29 October 2014 14:52, Richard Weinberger <richard@nod.at> wrote:
>>> diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h
>>> index c3918a0..82b693f 100644
>>> --- a/include/linux/mtd/ubi.h
>>> +++ b/include/linux/mtd/ubi.h
>>> @@ -34,11 +34,13 @@
>>>   * UBI_READONLY: read-only mode
>>>   * UBI_READWRITE: read-write mode
>>>   * UBI_EXCLUSIVE: exclusive mode
>>> + * UBI_METAONLY: modify voulme meta data only
>>
>> Typo - s/voulme/volume/g
>
> Thanks. :)
>
>>>   */
>>>  enum {
>>>         UBI_READONLY = 1,
>>>         UBI_READWRITE,
>>> -       UBI_EXCLUSIVE
>>> +       UBI_EXCLUSIVE,
>>> +       UBI_METAONLY
>>>  };
>>>
>>
>> Also you may want to add something similar to this:
>>
>> --- a/drivers/mtd/ubi/ubi.h
>> +++ b/drivers/mtd/ubi/ubi.h
>> @@ -339,7 +339,7 @@ struct ubi_volume {
>>  /**
>>   * struct ubi_volume_desc - UBI volume descriptor returned when it is opened.
>>   * @vol: reference to the corresponding volume description object
>> - * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, or %UBI_EXCLUSIVE)
>> + * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, %UBI_EXCLUSIVE or
>> %UBI_METAONLY)
>>   */
>>  struct ubi_volume_desc {
>>         struct ubi_volume *vol;
>>
>> There is also a similar mention in gluebi.c: 'readers/writes/exclusive'.
>
> Please send a patch for that. :)

Apologies for the delay - did you just want junk a hunk so you can
include in your next revision - or did you want me to come up with a
v2 of your patch?

Andrew Murray

>
> Thanks,
> //richard

Re: [PATCH 1/2] UBI: Implement UBI_METAONLY

[Richard Weinberger]

Am 07.11.2014 um 13:42 schrieb Andrew Murray:
>> Please send a patch for that. :)
> 
> Apologies for the delay - did you just want junk a hunk so you can
> include in your next revision - or did you want me to come up with a
> v2 of your patch?

I have to say sorry, your mail got lost in my inbox. :-(
The change in ubi.h is trivial, I've added it directly to my patch.
If you want you can send a patch for gluebi.c.

Thanks,
//richard

Re: [PATCH 1/2] UBI: Implement UBI_METAONLY

[Artem Bityutskiy]

On Wed, 2014-10-29 at 15:52 +0100, Richard Weinberger wrote:
> + * UBI_METAONLY: modify voulme meta data only

Can we please have a bit extended comment for this, explaining what
meta-data is? Like

UBI_METAONLY: modify only the volume meta-data, i.e. the data stored in
              the volume table, but not in any of volume LEBs.

[PATCH 1/2] UBI: Implement UBI_METAONLY

[Richard Weinberger]

UBI_METAONLY is a new open mode for UBI volumes, it indicates
that only meta data is being changed.
Meta data in terms of UBI volumes means data which is stored in the
UBI volume table but not on the volume itself.
While it does not interfere with UBI_READONLY and UBI_READWRITE
it is not allowed to use UBI_METAONLY together with UBI_EXCLUSIVE.

Cc: Ezequiel Garcia <ezequiel.garcia@free-electrons.com>
Cc: Andrew Murray <amurray@embedded-bits.co.uk>
Signed-off-by: Richard Weinberger <richard@nod.at>
---
 drivers/mtd/ubi/cdev.c  |  8 +++++---
 drivers/mtd/ubi/kapi.c  | 15 +++++++++++++--
 drivers/mtd/ubi/ubi.h   |  8 ++++++--
 include/linux/mtd/ubi.h |  5 ++++-
 4 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/drivers/mtd/ubi/cdev.c b/drivers/mtd/ubi/cdev.c
index 3410ea81..f5c715c 100644
--- a/drivers/mtd/ubi/cdev.c
+++ b/drivers/mtd/ubi/cdev.c
@@ -61,13 +61,13 @@ static int get_exclusive(struct ubi_device *ubi, struct ubi_volume_desc *desc)
 	struct ubi_volume *vol = desc->vol;
 
 	spin_lock(&vol->ubi->volumes_lock);
-	users = vol->readers + vol->writers + vol->exclusive;
+	users = vol->readers + vol->writers + vol->exclusive + vol->metaonly;
 	ubi_assert(users > 0);
 	if (users > 1) {
 		ubi_err(ubi, "%d users for volume %d", users, vol->vol_id);
 		err = -EBUSY;
 	} else {
-		vol->readers = vol->writers = 0;
+		vol->readers = vol->writers = vol->metaonly = 0;
 		vol->exclusive = 1;
 		err = desc->mode;
 		desc->mode = UBI_EXCLUSIVE;
@@ -87,13 +87,15 @@ static void revoke_exclusive(struct ubi_volume_desc *desc, int mode)
 	struct ubi_volume *vol = desc->vol;
 
 	spin_lock(&vol->ubi->volumes_lock);
-	ubi_assert(vol->readers == 0 && vol->writers == 0);
+	ubi_assert(vol->readers == 0 && vol->writers == 0 && vol->metaonly == 0);
 	ubi_assert(vol->exclusive == 1 && desc->mode == UBI_EXCLUSIVE);
 	vol->exclusive = 0;
 	if (mode == UBI_READONLY)
 		vol->readers = 1;
 	else if (mode == UBI_READWRITE)
 		vol->writers = 1;
+	else if (mode == UBI_METAONLY)
+		vol->metaonly = 1;
 	else
 		vol->exclusive = 1;
 	spin_unlock(&vol->ubi->volumes_lock);
diff --git a/drivers/mtd/ubi/kapi.c b/drivers/mtd/ubi/kapi.c
index f3bab66..589c423 100644
--- a/drivers/mtd/ubi/kapi.c
+++ b/drivers/mtd/ubi/kapi.c
@@ -137,7 +137,7 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 		return ERR_PTR(-EINVAL);
 
 	if (mode != UBI_READONLY && mode != UBI_READWRITE &&
-	    mode != UBI_EXCLUSIVE)
+	    mode != UBI_EXCLUSIVE && mode != UBI_METAONLY)
 		return ERR_PTR(-EINVAL);
 
 	/*
@@ -182,10 +182,17 @@ struct ubi_volume_desc *ubi_open_volume(int ubi_num, int vol_id, int mode)
 		break;
 
 	case UBI_EXCLUSIVE:
-		if (vol->exclusive || vol->writers || vol->readers)
+		if (vol->exclusive || vol->writers || vol->readers ||
+		    vol->metaonly)
 			goto out_unlock;
 		vol->exclusive = 1;
 		break;
+
+	case UBI_METAONLY:
+		if (vol->metaonly || vol->exclusive)
+			goto out_unlock;
+		vol->metaonly = 1;
+		break;
 	}
 	get_device(&vol->dev);
 	vol->ref_count += 1;
@@ -343,6 +350,10 @@ void ubi_close_volume(struct ubi_volume_desc *desc)
 		break;
 	case UBI_EXCLUSIVE:
 		vol->exclusive = 0;
+		break;
+	case UBI_METAONLY:
+		vol->metaonly = 0;
+		break;
 	}
 	vol->ref_count -= 1;
 	spin_unlock(&ubi->volumes_lock);
diff --git a/drivers/mtd/ubi/ubi.h b/drivers/mtd/ubi/ubi.h
index f80ffab..20cabc0 100644
--- a/drivers/mtd/ubi/ubi.h
+++ b/drivers/mtd/ubi/ubi.h
@@ -261,6 +261,7 @@ struct ubi_fm_pool {
  * @readers: number of users holding this volume in read-only mode
  * @writers: number of users holding this volume in read-write mode
  * @exclusive: whether somebody holds this volume in exclusive mode
+ * @metaonly: whether somebody is altering only meta data of this volume
  *
  * @reserved_pebs: how many physical eraseblocks are reserved for this volume
  * @vol_type: volume type (%UBI_DYNAMIC_VOLUME or %UBI_STATIC_VOLUME)
@@ -309,6 +310,7 @@ struct ubi_volume {
 	int readers;
 	int writers;
 	int exclusive;
+	int metaonly;
 
 	int reserved_pebs;
 	int vol_type;
@@ -339,7 +341,8 @@ struct ubi_volume {
 /**
  * struct ubi_volume_desc - UBI volume descriptor returned when it is opened.
  * @vol: reference to the corresponding volume description object
- * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, or %UBI_EXCLUSIVE)
+ * @mode: open mode (%UBI_READONLY, %UBI_READWRITE, %UBI_EXCLUSIVE
+ * or %UBI_METAONLY)
  */
 struct ubi_volume_desc {
 	struct ubi_volume *vol;
@@ -390,7 +393,8 @@ struct ubi_debug_info {
  * @volumes_lock: protects @volumes, @rsvd_pebs, @avail_pebs, beb_rsvd_pebs,
  *                @beb_rsvd_level, @bad_peb_count, @good_peb_count, @vol_count,
  *                @vol->readers, @vol->writers, @vol->exclusive,
- *                @vol->ref_count, @vol->mapping and @vol->eba_tbl.
+ *                @vol->metaonly, @vol->ref_count, @vol->mapping and
+ *                @vol->eba_tbl.
  * @ref_count: count of references on the UBI device
  * @image_seq: image sequence number recorded on EC headers
  *
diff --git a/include/linux/mtd/ubi.h b/include/linux/mtd/ubi.h
index c3918a0..8fa2753 100644
--- a/include/linux/mtd/ubi.h
+++ b/include/linux/mtd/ubi.h
@@ -34,11 +34,14 @@
  * UBI_READONLY: read-only mode
  * UBI_READWRITE: read-write mode
  * UBI_EXCLUSIVE: exclusive mode
+ * UBI_METAONLY: modify only the volume meta-data,
+ *  i.e. the data stored in the volume table, but not in any of volume LEBs.
  */
 enum {
 	UBI_READONLY = 1,
 	UBI_READWRITE,
-	UBI_EXCLUSIVE
+	UBI_EXCLUSIVE,
+	UBI_METAONLY
 };
 
 /**
-- 
1.8.4.5