Commit 3a39d90b authored by Jim Harris's avatar Jim Harris Committed by Tomasz Zawadzki
Browse files

bdev_gpt: add new SPDK partition type for off-by-one fix 



The gpt bdev module has an off-by-one error.  When it
calculates the size of the partition, it simply does
"end - start", when really it should be "end - start + 1".

We cannot just fix it by changing the math here, any
consumers of the partition may have put down metadata
on the partition based on the old size.

So instead add a new SPDK partition type.  SPDK will keep
the existing off-by-one behavior when it finds the old
partition type, but will use the correct math when finding
the new partition type.

Fixes issue #2801.

Signed-off-by: default avatarJim Harris <james.r.harris@intel.com>
Change-Id: I48eb48c781f1968b59e52b4477ca45e9c81eac11
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/16298


Tested-by: default avatarSPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: default avatarAleksey Marchuk <alexeymar@nvidia.com>
Reviewed-by: default avatarPaul Luse <paul.e.luse@intel.com>
Reviewed-by: default avatarMike Gerdts <mgerdts@nvidia.com>
Reviewed-by: default avatarTomasz Zawadzki <tomasz.zawadzki@intel.com>
parent 40e8ee2a

deprecation.md

+15 −0
Original line number Diff line number Diff line
@@ -43,3 +43,18 @@ With the removal of this deprecation, calls to vbdev modules' `examine_disk()` a 
`examine_config()` callbacks will happen only on the app thread. This means that vbdev module

maintainers will not need to make any changes to examine callbacks that call `spdk_bdev_register()`

on the same thread as the examine callback uses.



### gpt



### `old_gpt_guid`



Deprecated the SPDK partition type GUID `7c5222bd-8f5d-4087-9c00-bf9843c7b58c`. Partitions of this

type have bdevs created that are one block less than the actual size of the partition. Existing

partitions using the deprecated GUID can continue to use that GUID; support for the deprecated GUID

will remain in SPDK indefinitely, and will continue to exhibit the off-by-one bug so that on-disk

metadata layouts based on the incorrect size are not affected.



See GitHub issue [2801](https://github.com/spdk/spdk/issues/2801) for additional details on the bug.



New SPDK partition types should use GUID `6527994e-2c5a-4eec-9613-8f5944074e8b` which will create

a bdev of the correct size.

doc/bdev.md

+2 −2
Original line number Diff line number Diff line
@@ -274,7 +274,7 @@ possibly multiple virtual bdevs. 


### SPDK GPT partition table {#bdev_ug_gpt}



The SPDK partition type GUID is `7c5222bd-8f5d-4087-9c00-bf9843c7b58c`. Existing SPDK bdevs

The SPDK partition type GUID is `6527994e-2c5a-4eec-9613-8f5944074e8b`. Existing SPDK bdevs

can be exposed as Linux block devices via NBD and then can be partitioned with

standard partitioning tools. After partitioning, the bdevs will need to be deleted and

attached again for the GPT bdev module to see any changes. NBD kernel module must be
@@ -312,7 +312,7 @@ parted -s /dev/nbd0 mkpart MyPartition '0%' '50%' 


# Change the partition type to the SPDK GUID.

# sgdisk is part of the gdisk package.

sgdisk -t 1:7c5222bd-8f5d-4087-9c00-bf9843c7b58c /dev/nbd0

sgdisk -t 1:6527994e-2c5a-4eec-9613-8f5944074e8b /dev/nbd0



# Stop the NBD device (stop exporting /dev/nbd0).

rpc.py nbd_stop_disk /dev/nbd0

module/bdev/gpt/gpt.h

+17 −1
Original line number Diff line number Diff line
@@ -13,8 +13,24 @@ 
#include "spdk/stdinc.h"



#include "spdk/gpt_spec.h"

#include "spdk/log.h"



#define SPDK_GPT_PART_TYPE_GUID     SPDK_GPT_GUID(0x6527994e, 0x2c5a, 0x4eec, 0x9613, 0x8f5944074e8b)



/* PART_TYPE_GUID_OLD partitions will be constructed as bdevs with one fewer block than expected.

 * See GitHub issue #2801.

 */

#ifdef REGISTER_GUID_DEPRECATION

/* Register the deprecation in the header file, to make it clear to readers that this GUID

 * shouldn't be used for new SPDK GPT partitions.  We will never actually log this deprecation

 * though, since we are not recommending that users try to migrate existing partitions with the

 * old GUID to the new GUID. Wrap it in this REGISTER_GUID_DEPRECATION flag to avoid defining

 * this deprecation in multiple compilation units.

 */

SPDK_LOG_DEPRECATION_REGISTER(old_gpt_guid, "old gpt guid", "Never", 0)

#endif

#define SPDK_GPT_PART_TYPE_GUID_OLD SPDK_GPT_GUID(0x7c5222bd, 0x8f5d, 0x4087, 0x9c00, 0xbf9843c7b58c)



#define SPDK_GPT_PART_TYPE_GUID SPDK_GPT_GUID(0x7c5222bd, 0x8f5d, 0x4087, 0x9c00, 0xbf9843c7b58c)

#define SPDK_GPT_BUFFER_SIZE 32768  /* 32KB */

#define	SPDK_GPT_GUID_EQUAL(x,y) (memcmp(x, y, sizeof(struct spdk_gpt_guid)) == 0)

module/bdev/gpt/vbdev_gpt.c

+19 −4
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
 * each partition.

 */



#define REGISTER_GUID_DEPRECATION

#include "gpt.h"



#include "spdk/endian.h"
@@ -313,12 +314,26 @@ vbdev_gpt_create_bdevs(struct gpt_base *gpt_base) 
		p = &gpt->partitions[i];

		uint64_t lba_start = from_le64(&p->starting_lba);

		uint64_t lba_end = from_le64(&p->ending_lba);

		uint64_t partition_size = lba_end - lba_start + 1;



		if (!SPDK_GPT_GUID_EQUAL(&gpt->partitions[i].part_type_guid,

					 &SPDK_GPT_PART_TYPE_GUID) ||

		    lba_start == 0) {

		if (lba_start == 0) {

			continue;

		}



		if (SPDK_GPT_GUID_EQUAL(&gpt->partitions[i].part_type_guid,

					&SPDK_GPT_PART_TYPE_GUID_OLD)) {

			/* GitHub issue #2801 - we continue to report these partitions with

			 * off-by-one sizing error to ensure we don't break layouts based

			 * on that smaller size. */

			partition_size -= 1;

		} else if (!SPDK_GPT_GUID_EQUAL(&gpt->partitions[i].part_type_guid,

						&SPDK_GPT_PART_TYPE_GUID)) {

			/* Partition type isn't TYPE_GUID or TYPE_GUID_OLD, so this isn't

			 * an SPDK parition.  Continue to the next partition.

			 */

			continue;

		}



		if (lba_start < head_lba_start || lba_end > head_lba_end) {

			continue;

		}
@@ -339,7 +354,7 @@ vbdev_gpt_create_bdevs(struct gpt_base *gpt_base) 
		}



		rc = spdk_bdev_part_construct(&d->part, gpt_base->part_base, name,

					      lba_start, lba_end - lba_start, "GPT Disk");

					      lba_start, partition_size, "GPT Disk");

		free(name);

		if (rc) {

			SPDK_ERRLOG("could not construct bdev part\n");

scripts/common.sh

+14 −1
Original line number Diff line number Diff line
@@ -361,12 +361,25 @@ block_in_use() { 
	return 0

}



get_spdk_gpt_old() {

	local spdk_guid



	[[ -e $rootdir/module/bdev/gpt/gpt.h ]] || return 1



	GPT_H="$rootdir/module/bdev/gpt/gpt.h"

	IFS="()" read -r _ spdk_guid _ < <(grep -w SPDK_GPT_PART_TYPE_GUID_OLD "$GPT_H")

	spdk_guid=${spdk_guid//, /-} spdk_guid=${spdk_guid//0x/}



	echo "$spdk_guid"

}



get_spdk_gpt() {

	local spdk_guid



	[[ -e $rootdir/module/bdev/gpt/gpt.h ]] || return 1



	IFS="()" read -r _ spdk_guid _ < <(grep SPDK_GPT_PART_TYPE_GUID "$rootdir/module/bdev/gpt/gpt.h")

	GPT_H="$rootdir/module/bdev/gpt/gpt.h"

	IFS="()" read -r _ spdk_guid _ < <(grep -w SPDK_GPT_PART_TYPE_GUID "$GPT_H")

	spdk_guid=${spdk_guid//, /-} spdk_guid=${spdk_guid//0x/}



	echo "$spdk_guid"