On 6/22/21 6:19 PM, Hannes Reinecke wrote:
> On 6/15/21 7:49 AM, Coly Li wrote:
>> This patch initializes the prototype data structures for nvm pages
>> allocator,
>>
>> - struct bch_nvm_pages_sb
>> This is the super block allocated on each nvdimm namespace. A nvdimm
>> set may have multiple namespaces, bch_nvm_pages_sb->set_uuid is used
>> to mark which nvdimm set this name space belongs to. Normally we will
>> use the bcache's cache set UUID to initialize this uuid, to connect this
>> nvdimm set to a specified bcache cache set.
>>
>> - struct bch_owner_list_head
>> This is a table for all heads of all owner lists. A owner list records
>> which page(s) allocated to which owner. After reboot from power failure,
>> the ownwer may find all its requested and allocated pages from the owner
> owner
Fixed for next post.
>
>> list by a handler which is converted by a UUID.
>>
>> - struct bch_nvm_pages_owner_head
>> This is a head of an owner list. Each owner only has one owner list,
>> and a nvm page only belongs to an specific owner. uuid[] will be set to
>> owner's uuid, for bcache it is the bcache's cache set uuid. label is not
>> mandatory, it is a human-readable string for debug purpose. The pointer
>> *recs references to separated nvm page which hold the table of struct
>> bch_nvm_pgalloc_rec.
>>
>> - struct bch_nvm_pgalloc_recs
>> This struct occupies a whole page, owner_uuid should match the uuid
>> in struct bch_nvm_pages_owner_head. recs[] is the real table contains all
>> allocated records.
>>
>> - struct bch_nvm_pgalloc_rec
>> Each structure records a range of allocated nvm pages.
>> - Bits 0 - 51: is pages offset of the allocated pages.
>> - Bits 52 - 57: allocaed size in page_size * order-of-2
>> - Bits 58 - 63: reserved.
>> Since each of the allocated nvm pages are power of 2, using 6 bits to
>> represent allocated size can have (1<<(1<<64) - 1) * PAGE_SIZE maximum
>> value. It can be a 76 bits width range size in byte for 4KB page size,
>> which is large enough currently.
>>
>> Signed-off-by: Coly Li <colyli@xxxxxxx>
>> Cc: Jianpeng Ma <jianpeng.ma@xxxxxxxxx>
>> Cc: Qiaowei Ren <qiaowei.ren@xxxxxxxxx>
>> ---
>> include/uapi/linux/bcache-nvm.h | 200 ++++++++++++++++++++++++++++++++
>> 1 file changed, 200 insertions(+)
>> create mode 100644 include/uapi/linux/bcache-nvm.h
>>
>> diff --git a/include/uapi/linux/bcache-nvm.h b/include/uapi/linux/bcache-nvm.h
>> new file mode 100644
>> index 000000000000..5094a6797679
>> --- /dev/null
>> +++ b/include/uapi/linux/bcache-nvm.h
>> @@ -0,0 +1,200 @@
>> +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
>> +
>> +#ifndef _UAPI_BCACHE_NVM_H
>> +#define _UAPI_BCACHE_NVM_H
>> +
>> +#if (__BITS_PER_LONG == 64)
>> +/*
>> + * Bcache on NVDIMM data structures
>> + */
>> +
>> +/*
>> + * - struct bch_nvm_pages_sb
>> + * This is the super block allocated on each nvdimm namespace. A nvdimm
>> + * set may have multiple namespaces, bch_nvm_pages_sb->set_uuid is used to mark
>> + * which nvdimm set this name space belongs to. Normally we will use the
>> + * bcache's cache set UUID to initialize this uuid, to connect this nvdimm
>> + * set to a specified bcache cache set.
>> + *
>> + * - struct bch_owner_list_head
>> + * This is a table for all heads of all owner lists. A owner list records
>> + * which page(s) allocated to which owner. After reboot from power failure,
>> + * the ownwer may find all its requested and allocated pages from the owner
>> + * list by a handler which is converted by a UUID.
>> + *
>> + * - struct bch_nvm_pages_owner_head
>> + * This is a head of an owner list. Each owner only has one owner list,
>> + * and a nvm page only belongs to an specific owner. uuid[] will be set to
>> + * owner's uuid, for bcache it is the bcache's cache set uuid. label is not
>> + * mandatory, it is a human-readable string for debug purpose. The pointer
>> + * recs references to separated nvm page which hold the table of struct
>> + * bch_pgalloc_rec.
>> + *
>> + *- struct bch_nvm_pgalloc_recs
>> + * This structure occupies a whole page, owner_uuid should match the uuid
>> + * in struct bch_nvm_pages_owner_head. recs[] is the real table contains all
>> + * allocated records.
>> + *
>> + * - struct bch_pgalloc_rec
>> + * Each structure records a range of allocated nvm pages. pgoff is offset
>> + * in unit of page size of this allocated nvm page range. The adjoint page
>> + * ranges of same owner can be merged into a larger one, therefore pages_nr
>> + * is NOT always power of 2.
>> + *
>> + *
>> + * Memory layout on nvdimm namespace 0
>> + *
>> + * 0 +---------------------------------+
>> + * | |
>> + * 4KB +---------------------------------+
>> + * | bch_nvm_pages_sb |
>> + * 8KB +---------------------------------+ <--- bch_nvm_pages_sb.bch_owner_list_head
>> + * | bch_owner_list_head |
>> + * | |
>> + * 16KB +---------------------------------+ <--- bch_owner_list_head.heads[0].recs[0]
>> + * | bch_nvm_pgalloc_recs |
>> + * | (nvm pages internal usage) |
>> + * 24KB +---------------------------------+
>> + * | |
>> + * | |
>> + * 16MB +---------------------------------+
>> + * | allocable nvm pages |
>> + * | for buddy allocator |
>> + * end +---------------------------------+
>> + *
>> + *
>> + *
>> + * Memory layout on nvdimm namespace N
>> + * (doesn't have owner list)
>> + *
>> + * 0 +---------------------------------+
>> + * | |
>> + * 4KB +---------------------------------+
>> + * | bch_nvm_pages_sb |
>> + * 8KB +---------------------------------+
>> + * | |
>> + * | |
>> + * | |
>> + * | |
>> + * | |
>> + * | |
>> + * 16MB +---------------------------------+
>> + * | allocable nvm pages |
>> + * | for buddy allocator |
>> + * end +---------------------------------+
>> + *
>> + */
>> +
>> +#include <linux/types.h>
>> +
>> +/* In sectors */
>> +#define BCH_NVM_PAGES_SB_OFFSET 4096
>> +#define BCH_NVM_PAGES_OFFSET (16 << 20)
>> +
>> +#define BCH_NVM_PAGES_LABEL_SIZE 32
>> +#define BCH_NVM_PAGES_NAMESPACES_MAX 8
>> +
>> +#define BCH_NVM_PAGES_OWNER_LIST_HEAD_OFFSET (8<<10)
>> +#define BCH_NVM_PAGES_SYS_RECS_HEAD_OFFSET (16<<10)
>> +
>> +#define BCH_NVM_PAGES_SB_VERSION 0
>> +#define BCH_NVM_PAGES_SB_VERSION_MAX 0
>> +
>> +static const unsigned char bch_nvm_pages_magic[] = {
>> + 0x17, 0xbd, 0x53, 0x7f, 0x1b, 0x23, 0xd6, 0x83,
>> + 0x46, 0xa4, 0xf8, 0x28, 0x17, 0xda, 0xec, 0xa9 };
>> +static const unsigned char bch_nvm_pages_pgalloc_magic[] = {
>> + 0x39, 0x25, 0x3f, 0xf7, 0x27, 0x17, 0xd0, 0xb9,
>> + 0x10, 0xe6, 0xd2, 0xda, 0x38, 0x68, 0x26, 0xae };
>> +
>> +/* takes 64bit width */
>> +struct bch_pgalloc_rec {
>> + __u64 pgoff:52;
>> + __u64 order:6;
>> + __u64 reserved:6;
>> +};
>> +
>> +struct bch_nvm_pgalloc_recs {
>> +union {
> Indentation.
Copied. It will be updated in next post.
>
>> + struct {
>> + struct bch_nvm_pages_owner_head *owner;
>> + struct bch_nvm_pgalloc_recs *next;
>> + unsigned char magic[16];
>> + unsigned char owner_uuid[16];
>> + unsigned int size;
>> + unsigned int used;
>> + unsigned long _pad[4];
>> + struct bch_pgalloc_rec recs[];
>> + };
>> + unsigned char pad[8192];
>> +};
>> +};
>> +
> Consider using __u64 and friends when specifying a structure with a
> fixed alignment; that also removes the need of the BITS_PER_LONG ifdef
> at the top.
It _WAS_ the first version how we did. But Jens didn't agree with this:
"This doesn't look right in a user header, any user API should be 32-bit
and 64-bit agnostic."
My following explanation was not convinced, then I change all the
__u32, __u64 stuffs into unsigned int, and unsigned long.
Considering nvm-pages allocator works only for both register word and
physical address are all 64 bits width, unsigned long will exactly
match 64bit and unsigned int will exactly match 32bit, I am fine to
use any of the forms. Jens is the upper layer maintainer, I choose to
listen to him.
>> +#define BCH_MAX_RECS \
>> + ((sizeof(struct bch_nvm_pgalloc_recs) - \
>> + offsetof(struct bch_nvm_pgalloc_recs, recs)) / \
>> + sizeof(struct bch_pgalloc_rec))
>> +
> What _are_ you doing here?
BCH_MAX_RECS is a consistent value, to indicate how many elements can
be stored in array recs[] from struct bch_nvm_pgalloc_recs.
> You're not seriously using the 'pad' field as a placeholder to size the
> structure accordingly?
The code is in the way as you expected. The 8KB pad forces struct
bch_nvm_pgalloc_recs to be
two 4K pages, which is an ordered size from the nvm-pages buddy allocator.
> Also, what is the size of the 'bch_nvm_pgalloc_recs' structure?
> 8k + header size?
struct bch_nvm_pgalloc_recs is exactly 8K. The header is inside the 8K
space.
> That is very awkward, as the page allocator won't be able to handle it
> efficiently.
> Please size it to either 8k or 16k overall.
> And if you do that you can simplify this define.
In memory layout of struct bch_nvm_pgalloc_recs is
|<------------ 8K ----------->|
[header] [recs ...............]
|<-- BCH_MAX_RECS -->|
So the code works same as your expectation.
>
>> +struct bch_nvm_pages_owner_head {
>> + unsigned char uuid[16];
>> + unsigned char label[BCH_NVM_PAGES_LABEL_SIZE];
>> + /* Per-namespace own lists */
>> + struct bch_nvm_pgalloc_recs *recs[BCH_NVM_PAGES_NAMESPACES_MAX];
>> +};
>> +
>> +/* heads[0] is always for nvm_pages internal usage */
>> +struct bch_owner_list_head {
>> +union {
>> + struct {
>> + unsigned int size;
>> + unsigned int used;
>> + unsigned long _pad[4];
>> + struct bch_nvm_pages_owner_head heads[];
>> + };
>> + unsigned char pad[8192];
>> +};
>> +};
>> +#define BCH_MAX_OWNER_LIST \
>> + ((sizeof(struct bch_owner_list_head) - \
>> + offsetof(struct bch_owner_list_head, heads)) / \
>> + sizeof(struct bch_nvm_pages_owner_head))
>> +
> Same here.
> Please size it that the 'bch_owner_list_head' structure fits into either
> 8k or 16k.
It works as you expected. But I realize maybe the indent is misleading.
I should add a blank before offsetof(), like this,
163 #define BCH_MAX_OWNER_LIST \
164 ((sizeof(struct bch_owner_list_head) - \
165 offsetof(struct bch_owner_list_head, heads)) /\
166 sizeof(struct bch_nvm_pages_owner_head))
It means (8K - header_size) / sizeof(struct bch_nvm_pages_owner_head).
>
>> +/* The on-media bit order is local CPU order */
>> +struct bch_nvm_pages_sb {
>> + unsigned long csum;
>> + unsigned long ns_start;
>> + unsigned long sb_offset;
>> + unsigned long version;
>> + unsigned char magic[16];
>> + unsigned char uuid[16];
>> + unsigned int page_size;
>> + unsigned int total_namespaces_nr;
>> + unsigned int this_namespace_nr;
>> + union {
>> + unsigned char set_uuid[16];
>> + unsigned long set_magic;
>> + };
>> +
>> + unsigned long flags;
>> + unsigned long seq;
>> +
>> + unsigned long feature_compat;
>> + unsigned long feature_incompat;
>> + unsigned long feature_ro_compat;
>> +
>> + /* For allocable nvm pages from buddy systems */
>> + unsigned long pages_offset;
>> + unsigned long pages_total;
>> +
>> + unsigned long pad[8];
>> +
>> + /* Only on the first name space */
>> + struct bch_owner_list_head *owner_list_head;
>> +
>> + /* Just for csum_set() */
>> + unsigned int keys;
>> + unsigned long d[0];
>> +};
>>
Thanks for your review. I will update all addressed locations except for
the __u32/__u64 stuffs, because Jens
didn't want them.
Coly Li
