linux_dsm_epyc7002/drivers/nvdimm/label.h
Gustavo A. R. Silva 1e361632da libnvdimm/label: Replace zero-length array with flexible-array member
The current codebase makes use of the zero-length array language
extension to the C90 standard, but the preferred mechanism to declare
variable-length types such as these ones is a flexible array member[1][2],
introduced in C99:

struct foo {
        int stuff;
        struct boo array[];
};

By making use of the mechanism above, we will get a compiler warning
in case the flexible array does not occur last in the structure, which
will help us prevent some kind of undefined behavior bugs from being
inadvertently introduced[3] to the codebase from now on.

Also, notice that, dynamic memory allocations won't be affected by
this change:

"Flexible array members have incomplete type, and so the sizeof operator
may not be applied. As a quirk of the original implementation of
zero-length arrays, sizeof evaluates to zero."[1]

This issue was found with the help of Coccinelle.

[1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html
[2] https://github.com/KSPP/linux/issues/21
[3] commit 7649773293 ("cxgb3/l2t: Fix undefined behaviour")

Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Link: https://lore.kernel.org/r/20200319230737.GA16452@embeddedor.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
2020-03-30 12:37:09 -07:00

147 lines
4.1 KiB
C

/* SPDX-License-Identifier: GPL-2.0-only */
/*
* Copyright(c) 2013-2015 Intel Corporation. All rights reserved.
*/
#ifndef __LABEL_H__
#define __LABEL_H__
#include <linux/ndctl.h>
#include <linux/sizes.h>
#include <linux/uuid.h>
#include <linux/io.h>
enum {
NSINDEX_SIG_LEN = 16,
NSINDEX_ALIGN = 256,
NSINDEX_SEQ_MASK = 0x3,
NSLABEL_UUID_LEN = 16,
NSLABEL_NAME_LEN = 64,
NSLABEL_FLAG_ROLABEL = 0x1, /* read-only label */
NSLABEL_FLAG_LOCAL = 0x2, /* DIMM-local namespace */
NSLABEL_FLAG_BTT = 0x4, /* namespace contains a BTT */
NSLABEL_FLAG_UPDATING = 0x8, /* label being updated */
BTT_ALIGN = 4096, /* all btt structures */
BTTINFO_SIG_LEN = 16,
BTTINFO_UUID_LEN = 16,
BTTINFO_FLAG_ERROR = 0x1, /* error state (read-only) */
BTTINFO_MAJOR_VERSION = 1,
ND_LABEL_MIN_SIZE = 256 * 4, /* see sizeof_namespace_index() */
ND_LABEL_ID_SIZE = 50,
ND_NSINDEX_INIT = 0x1,
};
/**
* struct nd_namespace_index - label set superblock
* @sig: NAMESPACE_INDEX\0
* @flags: placeholder
* @seq: sequence number for this index
* @myoff: offset of this index in label area
* @mysize: size of this index struct
* @otheroff: offset of other index
* @labeloff: offset of first label slot
* @nslot: total number of label slots
* @major: label area major version
* @minor: label area minor version
* @checksum: fletcher64 of all fields
* @free[0]: bitmap, nlabel bits
*
* The size of free[] is rounded up so the total struct size is a
* multiple of NSINDEX_ALIGN bytes. Any bits this allocates beyond
* nlabel bits must be zero.
*/
struct nd_namespace_index {
u8 sig[NSINDEX_SIG_LEN];
u8 flags[3];
u8 labelsize;
__le32 seq;
__le64 myoff;
__le64 mysize;
__le64 otheroff;
__le64 labeloff;
__le32 nslot;
__le16 major;
__le16 minor;
__le64 checksum;
u8 free[];
};
/**
* struct nd_namespace_label - namespace superblock
* @uuid: UUID per RFC 4122
* @name: optional name (NULL-terminated)
* @flags: see NSLABEL_FLAG_*
* @nlabel: num labels to describe this ns
* @position: labels position in set
* @isetcookie: interleave set cookie
* @lbasize: LBA size in bytes or 0 for pmem
* @dpa: DPA of NVM range on this DIMM
* @rawsize: size of namespace
* @slot: slot of this label in label area
* @unused: must be zero
*/
struct nd_namespace_label {
u8 uuid[NSLABEL_UUID_LEN];
u8 name[NSLABEL_NAME_LEN];
__le32 flags;
__le16 nlabel;
__le16 position;
__le64 isetcookie;
__le64 lbasize;
__le64 dpa;
__le64 rawsize;
__le32 slot;
/*
* Accessing fields past this point should be gated by a
* namespace_label_has() check.
*/
u8 align;
u8 reserved[3];
guid_t type_guid;
guid_t abstraction_guid;
u8 reserved2[88];
__le64 checksum;
};
#define NVDIMM_BTT_GUID "8aed63a2-29a2-4c66-8b12-f05d15d3922a"
#define NVDIMM_BTT2_GUID "18633bfc-1735-4217-8ac9-17239282d3f8"
#define NVDIMM_PFN_GUID "266400ba-fb9f-4677-bcb0-968f11d0d225"
#define NVDIMM_DAX_GUID "97a86d9c-3cdd-4eda-986f-5068b4f80088"
/**
* struct nd_label_id - identifier string for dpa allocation
* @id: "{blk|pmem}-<namespace uuid>"
*/
struct nd_label_id {
char id[ND_LABEL_ID_SIZE];
};
/*
* If the 'best' index is invalid, so is the 'next' index. Otherwise,
* the next index is MOD(index+1, 2)
*/
static inline int nd_label_next_nsindex(int index)
{
if (index < 0)
return -1;
return (index + 1) % 2;
}
struct nvdimm_drvdata;
int nd_label_data_init(struct nvdimm_drvdata *ndd);
size_t sizeof_namespace_index(struct nvdimm_drvdata *ndd);
int nd_label_active_count(struct nvdimm_drvdata *ndd);
struct nd_namespace_label *nd_label_active(struct nvdimm_drvdata *ndd, int n);
u32 nd_label_alloc_slot(struct nvdimm_drvdata *ndd);
bool nd_label_free_slot(struct nvdimm_drvdata *ndd, u32 slot);
u32 nd_label_nfree(struct nvdimm_drvdata *ndd);
enum nvdimm_claim_class to_nvdimm_cclass(guid_t *guid);
struct nd_region;
struct nd_namespace_pmem;
struct nd_namespace_blk;
int nd_pmem_namespace_label_update(struct nd_region *nd_region,
struct nd_namespace_pmem *nspm, resource_size_t size);
int nd_blk_namespace_label_update(struct nd_region *nd_region,
struct nd_namespace_blk *nsblk, resource_size_t size);
#endif /* __LABEL_H__ */