On 6/22/21 6:39 PM, Hannes Reinecke wrote:
> On 6/15/21 7:49 AM, Coly Li wrote:
>> From: Jianpeng Ma <jianpeng.ma@xxxxxxxxx>
>>
>> This patch define the prototype data structures in memory and
>> initializes the nvm pages allocator.
>>
>> The nvm address space which is managed by this allocator can consist of
>> many nvm namespaces, and some namespaces can compose into one nvm set,
>> like cache set. For this initial implementation, only one set can be
>> supported.
>>
>> The users of this nvm pages allocator need to call register_namespace()
>> to register the nvdimm device (like /dev/pmemX) into this allocator as
>> the instance of struct nvm_namespace.
>>
>> Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
>> Signed-off-by: Jianpeng Ma <jianpeng.ma@xxxxxxxxx>
>> Co-developed-by: Qiaowei Ren <qiaowei.ren@xxxxxxxxx>
>> Signed-off-by: Qiaowei Ren <qiaowei.ren@xxxxxxxxx>
>> Signed-off-by: Coly Li <colyli@xxxxxxx>
>> ---
>> drivers/md/bcache/Kconfig | 10 ++
>> drivers/md/bcache/Makefile | 1 +
>> drivers/md/bcache/nvm-pages.c | 295 ++++++++++++++++++++++++++++++++++
>> drivers/md/bcache/nvm-pages.h | 74 +++++++++
>> drivers/md/bcache/super.c | 3 +
>> 5 files changed, 383 insertions(+)
>> create mode 100644 drivers/md/bcache/nvm-pages.c
>> create mode 100644 drivers/md/bcache/nvm-pages.h
>>
>> diff --git a/drivers/md/bcache/Kconfig b/drivers/md/bcache/Kconfig
>> index d1ca4d059c20..a69f6c0e0507 100644
>> --- a/drivers/md/bcache/Kconfig
>> +++ b/drivers/md/bcache/Kconfig
>> @@ -35,3 +35,13 @@ config BCACHE_ASYNC_REGISTRATION
>> device path into this file will returns immediately and the real
>> registration work is handled in kernel work queue in asynchronous
>> way.
>> +
>> +config BCACHE_NVM_PAGES
>> + bool "NVDIMM support for bcache (EXPERIMENTAL)"
>> + depends on BCACHE
>> + depends on 64BIT
>> + depends on LIBNVDIMM
>> + depends on DAX
>> + help
>> + Allocate/release NV-memory pages for bcache and provide allocated pages
>> + for each requestor after system reboot.
>> diff --git a/drivers/md/bcache/Makefile b/drivers/md/bcache/Makefile
>> index 5b87e59676b8..2397bb7c7ffd 100644
>> --- a/drivers/md/bcache/Makefile
>> +++ b/drivers/md/bcache/Makefile
>> @@ -5,3 +5,4 @@ obj-$(CONFIG_BCACHE) += bcache.o
>> bcache-y := alloc.o bset.o btree.o closure.o debug.o extents.o\
>> io.o journal.o movinggc.o request.o stats.o super.o sysfs.o trace.o\
>> util.o writeback.o features.o
>> +bcache-$(CONFIG_BCACHE_NVM_PAGES) += nvm-pages.o
>> diff --git a/drivers/md/bcache/nvm-pages.c b/drivers/md/bcache/nvm-pages.c
>> new file mode 100644
>> index 000000000000..18fdadbc502f
>> --- /dev/null
>> +++ b/drivers/md/bcache/nvm-pages.c
>> @@ -0,0 +1,295 @@
>> +// SPDX-License-Identifier: GPL-2.0-only
>> +/*
>> + * Nvdimm page-buddy allocator
>> + *
>> + * Copyright (c) 2021, Intel Corporation.
>> + * Copyright (c) 2021, Qiaowei Ren <qiaowei.ren@xxxxxxxxx>.
>> + * Copyright (c) 2021, Jianpeng Ma <jianpeng.ma@xxxxxxxxx>.
>> + */
>> +
>> +#if defined(CONFIG_BCACHE_NVM_PAGES)
>> +
> No need for this 'if' statement as it'll be excluded by the Makefile
> anyway if the config option isn't set.
Such if is necessary because stub routines are defined when
CONFIG_BCACHE_NVM_PAGES is not defined, e.g.
426 +#else
427 +
428 +static inline struct bch_nvm_namespace
*bch_register_namespace(const char *dev_path)
429 +{
430 + return NULL;
431 +}
432 +static inline int bch_nvm_init(void)
433 +{
434 + return 0;
435 +}
436 +static inline void bch_nvm_exit(void) { }
437 +
438 +#endif /* CONFIG_BCACHE_NVM_PAGES */
>> +#include "bcache.h"
>> +#include "nvm-pages.h"
>> +
>> +#include <linux/slab.h>
>> +#include <linux/list.h>
>> +#include <linux/mutex.h>
>> +#include <linux/dax.h>
>> +#include <linux/pfn_t.h>
>> +#include <linux/libnvdimm.h>
>> +#include <linux/mm_types.h>
>> +#include <linux/err.h>
>> +#include <linux/pagemap.h>
>> +#include <linux/bitmap.h>
>> +#include <linux/blkdev.h>
>> +
>> +struct bch_nvm_set *only_set;
>> +
>> +static void release_nvm_namespaces(struct bch_nvm_set *nvm_set)
>> +{
>> + int i;
>> + struct bch_nvm_namespace *ns;
>> +
>> + for (i = 0; i < nvm_set->total_namespaces_nr; i++) {
>> + ns = nvm_set->nss[i];
>> + if (ns) {
>> + blkdev_put(ns->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXEC);
>> + kfree(ns);
>> + }
>> + }
>> +
>> + kfree(nvm_set->nss);
>> +}
>> +
>> +static void release_nvm_set(struct bch_nvm_set *nvm_set)
>> +{
>> + release_nvm_namespaces(nvm_set);
>> + kfree(nvm_set);
>> +}
>> +
>> +static int init_owner_info(struct bch_nvm_namespace *ns)
>> +{
>> + struct bch_owner_list_head *owner_list_head = ns->sb->owner_list_head;
>> +
>> + mutex_lock(&only_set->lock);
>> + only_set->owner_list_head = owner_list_head;
>> + only_set->owner_list_size = owner_list_head->size;
>> + only_set->owner_list_used = owner_list_head->used;
>> + mutex_unlock(&only_set->lock);
>> +
>> + return 0;
>> +}
>> +
>> +static int attach_nvm_set(struct bch_nvm_namespace *ns)
>> +{
>> + int rc = 0;
>> +
>> + mutex_lock(&only_set->lock);
>> + if (only_set->nss) {
>> + if (memcmp(ns->sb->set_uuid, only_set->set_uuid, 16)) {
>> + pr_info("namespace id doesn't match nvm set\n");
>> + rc = -EINVAL;
>> + goto unlock;
>> + }
>> +
>> + if (only_set->nss[ns->sb->this_namespace_nr]) {
> Doesn't this need to be checked against 'total_namespaces_nr' to avoid
> overflow?
Will add such checking in bch_register_namespace().
>> + pr_info("already has the same position(%d) nvm\n",
>> + ns->sb->this_namespace_nr);
>> + rc = -EEXIST;
>> + goto unlock;
>> + }
>> + } else {
>> + memcpy(only_set->set_uuid, ns->sb->set_uuid, 16);
>> + only_set->total_namespaces_nr = ns->sb->total_namespaces_nr;
>> + only_set->nss = kcalloc(only_set->total_namespaces_nr,
>> + sizeof(struct bch_nvm_namespace *), GFP_KERNEL);
>> + if (!only_set->nss) {
> When you enter here, 'set_uuid' and 'total_namespace_nr' is being
> modified, which might cause errors later on.
> Please move these two lines _after_ the kcalloc() to avoid this.
Yeah, modify the order is better.
I don't ask for change here during my code review is, only_set is
an in-memory object and only attach one name space currently.
only_set->set_uuid and only_set->total_namespaces_nr will not be
checked after "only_set->nss[ns->sb->this_namespace_nr] = ns".
So the code works correctly here.
But yes, we don't need unnecessary extra memory writing here. We
will modify here in next post.
>> + rc = -ENOMEM;
>> + goto unlock;
>> + }
>> + }
>> +
>> + only_set->nss[ns->sb->this_namespace_nr] = ns;
>> +
>> + /* Firstly attach */
> Initial attach?
Will fix in next post.
>
>> + if ((unsigned long)ns->sb->owner_list_head == BCH_NVM_PAGES_OWNER_LIST_HEAD_OFFSET) {
>> + struct bch_nvm_pages_owner_head *sys_owner_head;
>> + struct bch_nvm_pgalloc_recs *sys_pgalloc_recs;
>> +
>> + ns->sb->owner_list_head = ns->kaddr + BCH_NVM_PAGES_OWNER_LIST_HEAD_OFFSET;
>> + sys_pgalloc_recs = ns->kaddr + BCH_NVM_PAGES_SYS_RECS_HEAD_OFFSET;
>> +
>> + sys_owner_head = &(ns->sb->owner_list_head->heads[0]);
>> + sys_owner_head->recs[0] = sys_pgalloc_recs;
>> + ns->sb->csum = csum_set(ns->sb);
>> +
> Hmm. You are trying to pick up the 'list_head' structure from NVM, right?
No, this is not READ, it's WRITE onto NVDIMM.
sys_owner_head points to NVDIMM, since ns->sb->owner_list_head is updated,
the checksum of ns->sb should be updated to new value onto the NVDIMM.
This is what the above line does.
>
> In doing so, don't you need to validate the structure (eg by checking
> the checksum) before doing so to ensure that the contents are valid?
The check sum checking for READ is done in read_nvdimm_meta_super() in
following lines,
198 + r = -EINVAL;
199 + expected_csum = csum_set(sb);
200 + if (expected_csum != sb->csum) {
201 + pr_info("csum is not match with expected one\n");
202 + goto put_page;
203 + }
Once thing to note is, currently all NVDIMM update is not power failure
considered. This is the next big task to do after the first small code
base merged.
>> + sys_pgalloc_recs->owner = sys_owner_head;
>> + } else
>> + BUG_ON(ns->sb->owner_list_head !=
>> + (ns->kaddr + BCH_NVM_PAGES_OWNER_LIST_HEAD_OFFSET));
>> +
>> +unlock:
>> + mutex_unlock(&only_set->lock);
>> + return rc;
>> +}
>> +
>> +static int read_nvdimm_meta_super(struct block_device *bdev,
>> + struct bch_nvm_namespace *ns)
>> +{
>> + struct page *page;
>> + struct bch_nvm_pages_sb *sb;
>> + int r = 0;
>> + uint64_t expected_csum = 0;
>> +
>> + page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
>> + BCH_NVM_PAGES_SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL);
>> +
>> + if (IS_ERR(page))
>> + return -EIO;
>> +
>> + sb = (struct bch_nvm_pages_sb *)(page_address(page) +
>> + offset_in_page(BCH_NVM_PAGES_SB_OFFSET));
>> + r = -EINVAL;
>> + expected_csum = csum_set(sb);
>> + if (expected_csum != sb->csum) {
>> + pr_info("csum is not match with expected one\n");
>> + goto put_page;
>> + }
>> +
>> + if (memcmp(sb->magic, bch_nvm_pages_magic, 16)) {
>> + pr_info("invalid bch_nvm_pages_magic\n");
>> + goto put_page;
>> + }
>> +
>> + if (sb->total_namespaces_nr != 1) {
>> + pr_info("currently only support one nvm device\n");
>> + goto put_page;
>> + }
>> +
>> + if (sb->sb_offset != BCH_NVM_PAGES_SB_OFFSET) {
>> + pr_info("invalid superblock offset\n");
>> + goto put_page;
>> + }
>> +
>> + r = 0;
>> + /* temporary use for DAX API */
>> + ns->page_size = sb->page_size;
>> + ns->pages_total = sb->pages_total;
>> +
>> +put_page:
>> + put_page(page);
>> + return r;
>> +}
>> +
>> +struct bch_nvm_namespace *bch_register_namespace(const char *dev_path)
>> +{
>> + struct bch_nvm_namespace *ns;
>> + int err;
>> + pgoff_t pgoff;
>> + char buf[BDEVNAME_SIZE];
>> + struct block_device *bdev;
>> + int id;
>> + char *path = NULL;
>> +
>> + path = kstrndup(dev_path, 512, GFP_KERNEL);
>> + if (!path) {
>> + pr_err("kstrndup failed\n");
>> + return ERR_PTR(-ENOMEM);
>> + }
>> +
>> + bdev = blkdev_get_by_path(strim(path),
>> + FMODE_READ|FMODE_WRITE|FMODE_EXEC,
>> + only_set);
>> + if (IS_ERR(bdev)) {
>> + pr_info("get %s error: %ld\n", dev_path, PTR_ERR(bdev));
>> + kfree(path);
>> + return ERR_PTR(PTR_ERR(bdev));
>> + }
>> +
>> + err = -ENOMEM;
>> + ns = kzalloc(sizeof(struct bch_nvm_namespace), GFP_KERNEL);
>> + if (!ns)
>> + goto bdput;
>> +
>> + err = -EIO;
>> + if (read_nvdimm_meta_super(bdev, ns)) {
>> + pr_info("%s read nvdimm meta super block failed.\n",
>> + bdevname(bdev, buf));
>> + goto free_ns;
>> + }
>> +
>> + err = -EOPNOTSUPP;
>> + if (!bdev_dax_supported(bdev, ns->page_size)) {
>> + pr_info("%s don't support DAX\n", bdevname(bdev, buf));
>> + goto free_ns;
>> + }
>> +
>> + err = -EINVAL;
>> + if (bdev_dax_pgoff(bdev, 0, ns->page_size, &pgoff)) {
>> + pr_info("invalid offset of %s\n", bdevname(bdev, buf));
>> + goto free_ns;
>> + }
>> +
>> + err = -ENOMEM;
>> + ns->dax_dev = fs_dax_get_by_bdev(bdev);
>> + if (!ns->dax_dev) {
>> + pr_info("can't by dax device by %s\n", bdevname(bdev, buf));
>> + goto free_ns;
>> + }
>> +
>> + err = -EINVAL;
>> + id = dax_read_lock();
>> + if (dax_direct_access(ns->dax_dev, pgoff, ns->pages_total,
>> + &ns->kaddr, &ns->start_pfn) <= 0) {
>> + pr_info("dax_direct_access error\n");
>> + dax_read_unlock(id);
>> + goto free_ns;
>> + }
>> + dax_read_unlock(id);
>> +
>> + ns->sb = ns->kaddr + BCH_NVM_PAGES_SB_OFFSET;
>> +
> You already read the superblock in read_nvdimm_meta_super(), right?
> Wouldn't it be better to first do the 'dax_direct_access()' call, and
> then check the superblock?
> That way you'll ensure that dax_direct_access()' did the right thing;
> with the current code you are using two different methods of accessing
> the superblock, which theoretically can result in one method succeeding,
> the other not ...
We have to do it. Because the mapping size of dax_direct_access() is
from ns->pages_total, it is stored on NVDIMM. Before calling
dax_direct_acess()
we need to make sure ns is an valid super block stored on NVDIMM, then
we can
trust value of ns->pages_total to do the DAX mapping.
Another method is firstly mapping a small fixed range (e.g. 1GB), and
check whether the super block on NVDIMM is valid. If yes, re-map the
whole space indicated by ns->pages_total. But the two-times accessing cannot
be avoided.
>> + err = -EINVAL;
>> + /* Check magic again to make sure DAX mapping is correct */
>> + if (memcmp(ns->sb->magic, bch_nvm_pages_magic, 16)) {
>> + pr_info("invalid bch_nvm_pages_magic after DAX mapping\n");
>> + goto free_ns;
>> + }
>> +
>> + err = attach_nvm_set(ns);
>> + if (err < 0)
>> + goto free_ns;
>> +
>> + ns->page_size = ns->sb->page_size;
>> + ns->pages_offset = ns->sb->pages_offset;
>> + ns->pages_total = ns->sb->pages_total;
>> + ns->free = 0;
>> + ns->bdev = bdev;
>> + ns->nvm_set = only_set;
>> + mutex_init(&ns->lock);
>> +
>> + if (ns->sb->this_namespace_nr == 0) {
>> + pr_info("only first namespace contain owner info\n");
>> + err = init_owner_info(ns);
>> + if (err < 0) {
>> + pr_info("init_owner_info met error %d\n", err);
>> + only_set->nss[ns->sb->this_namespace_nr] = NULL;
>> + goto free_ns;
>> + }
>> + }
>> +
>> + kfree(path);
>> + return ns;
>> +free_ns:
>> + kfree(ns);
>> +bdput:
>> + blkdev_put(bdev, FMODE_READ|FMODE_WRITE|FMODE_EXEC);
>> + kfree(path);
>> + return ERR_PTR(err);
>> +}
>> +EXPORT_SYMBOL_GPL(bch_register_namespace);
>> +
>> +int __init bch_nvm_init(void)
>> +{
>> + only_set = kzalloc(sizeof(*only_set), GFP_KERNEL);
>> + if (!only_set)
>> + return -ENOMEM;
>> +
>> + only_set->total_namespaces_nr = 0;
>> + only_set->owner_list_head = NULL;
>> + only_set->nss = NULL;
>> +
>> + mutex_init(&only_set->lock);
>> +
>> + pr_info("bcache nvm init\n");
>> + return 0;
>> +}
>> +
>> +void bch_nvm_exit(void)
>> +{
>> + release_nvm_set(only_set);
>> + pr_info("bcache nvm exit\n");
>> +}
>> +
>> +#endif /* CONFIG_BCACHE_NVM_PAGES */
>> diff --git a/drivers/md/bcache/nvm-pages.h b/drivers/md/bcache/nvm-pages.h
>> new file mode 100644
>> index 000000000000..3e24c4dee7fd
>> --- /dev/null
>> +++ b/drivers/md/bcache/nvm-pages.h
>> @@ -0,0 +1,74 @@
>> +/* SPDX-License-Identifier: GPL-2.0 */
>> +
>> +#ifndef _BCACHE_NVM_PAGES_H
>> +#define _BCACHE_NVM_PAGES_H
>> +
>> +#if defined(CONFIG_BCACHE_NVM_PAGES)
>> +#include <linux/bcache-nvm.h>
>> +#endif /* CONFIG_BCACHE_NVM_PAGES */
>> +
> Hmm? What is that doing here?
> Please move it into the source file.
This is temporary before the whole NVDIMM support for bcache is completed.
drivers/md/bcache/nvm-pages.h has to be included because there are still
stub
routines in this header. Such stub routines like,
+static inline struct bch_nvm_namespace *bch_register_namespace(const char *dev_path)
+{
+ return NULL;
+}
will be removed after the whole code completed and merged. So currently we have to
do this to make sure the NVDIMM related code won't be leaked out if such experimental
configure is not enabled.
Thanks for your review. The addressed issue will be fixed and updated in next post.
Coly Li
>> +/*
>> + * Bcache NVDIMM in memory data structures
>> + */
>> +
>> +/*
>> + * The following three structures in memory records which page(s) allocated
>> + * to which owner. After reboot from power failure, they will be initialized
>> + * based on nvm pages superblock in NVDIMM device.
>> + */
>> +struct bch_nvm_namespace {
>> + struct bch_nvm_pages_sb *sb;
>> + void *kaddr;
>> +
>> + u8 uuid[16];
>> + u64 free;
>> + u32 page_size;
>> + u64 pages_offset;
>> + u64 pages_total;
>> + pfn_t start_pfn;
>> +
>> + struct dax_device *dax_dev;
>> + struct block_device *bdev;
>> + struct bch_nvm_set *nvm_set;
>> +
>> + struct mutex lock;
>> +};
>> +
>> +/*
>> + * A set of namespaces. Currently only one set can be supported.
>> + */
>> +struct bch_nvm_set {
>> + u8 set_uuid[16];
>> + u32 total_namespaces_nr;
>> +
>> + u32 owner_list_size;
>> + u32 owner_list_used;
>> + struct bch_owner_list_head *owner_list_head;
>> +
>> + struct bch_nvm_namespace **nss;
>> +
>> + struct mutex lock;
>> +};
>> +extern struct bch_nvm_set *only_set;
>> +
>> +#if defined(CONFIG_BCACHE_NVM_PAGES)
>> +
>> +struct bch_nvm_namespace *bch_register_namespace(const char *dev_path);
>> +int bch_nvm_init(void);
>> +void bch_nvm_exit(void);
>> +
>> +#else
>> +
>> +static inline struct bch_nvm_namespace *bch_register_namespace(const char *dev_path)
>> +{
>> + return NULL;
>> +}
>> +static inline int bch_nvm_init(void)
>> +{
>> + return 0;
>> +}
>> +static inline void bch_nvm_exit(void) { }
>> +
>> +#endif /* CONFIG_BCACHE_NVM_PAGES */
>> +
>> +#endif /* _BCACHE_NVM_PAGES_H */
>> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
>> index 2f1ee4fbf4d5..ce22aefb1352 100644
>> --- a/drivers/md/bcache/super.c
>> +++ b/drivers/md/bcache/super.c
>> @@ -14,6 +14,7 @@
>> #include "request.h"
>> #include "writeback.h"
>> #include "features.h"
>> +#include "nvm-pages.h"
>>
>> #include <linux/blkdev.h>
>> #include <linux/pagemap.h>
>> @@ -2823,6 +2824,7 @@ static void bcache_exit(void)
>> {
>> bch_debug_exit();
>> bch_request_exit();
>> + bch_nvm_exit();
>> if (bcache_kobj)
>> kobject_put(bcache_kobj);
>> if (bcache_wq)
>> @@ -2921,6 +2923,7 @@ static int __init bcache_init(void)
>>
>> bch_debug_init();
>> closure_debug_init();
>> + bch_nvm_init();
>>
>> bcache_is_reboot = false;
>>
>>
> Cheers,
>
> Hannes
