On Wed, Aug 11, 2021 at 10:04 AM Coly Li <colyli@xxxxxxx> 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>
> Cc: Christoph Hellwig <hch@xxxxxx>
> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
> Cc: Hannes Reinecke <hare@xxxxxxx>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> ---
> drivers/md/bcache/Kconfig | 10 +
> drivers/md/bcache/Makefile | 1 +
> drivers/md/bcache/nvm-pages.c | 339 ++++++++++++++++++++++++++++++++++
> drivers/md/bcache/nvm-pages.h | 96 ++++++++++
> drivers/md/bcache/super.c | 3 +
> 5 files changed, 449 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..6184c628d9cc
> --- /dev/null
> +++ b/drivers/md/bcache/nvm-pages.c
> @@ -0,0 +1,339 @@
> +// 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>.
> + */
> +
> +#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_nvmpg_set *global_nvmpg_set;
> +
> +void *bch_nvmpg_offset_to_ptr(unsigned long offset)
> +{
> + int ns_id = BCH_NVMPG_GET_NS_ID(offset);
> + struct bch_nvmpg_ns *ns = global_nvmpg_set->ns_tbl[ns_id];
> +
> + if (offset == 0)
> + return NULL;
> +
> + ns_id = BCH_NVMPG_GET_NS_ID(offset);
> + ns = global_nvmpg_set->ns_tbl[ns_id];
> +
> + if (ns)
> + return (void *)(ns->base_addr + BCH_NVMPG_GET_OFFSET(offset));
> +
> + pr_err("Invalid ns_id %u\n", ns_id);
> + return NULL;
> +}
> +
> +unsigned long bch_nvmpg_ptr_to_offset(struct bch_nvmpg_ns *ns, void *ptr)
> +{
> + int ns_id = ns->ns_id;
> + unsigned long offset = (unsigned long)(ptr - ns->base_addr);
> +
> + return BCH_NVMPG_OFFSET(ns_id, offset);
> +}
> +
> +static void release_ns_tbl(struct bch_nvmpg_set *set)
> +{
> + int i;
> + struct bch_nvmpg_ns *ns;
> +
> + for (i = 0; i < BCH_NVMPG_NS_MAX; i++) {
> + ns = set->ns_tbl[i];
> + if (ns) {
> + blkdev_put(ns->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXEC);
> + set->ns_tbl[i] = NULL;
> + set->attached_ns--;
> + kfree(ns);
> + }
> + }
> +
> + if (set->attached_ns)
> + pr_err("unexpected attached_ns: %u\n", set->attached_ns);
> +}
> +
> +static void release_nvmpg_set(struct bch_nvmpg_set *set)
> +{
> + release_ns_tbl(set);
> + kfree(set);
> +}
> +
> +/* Namespace 0 contains all meta data of the nvmpg allocation set */
> +static int init_nvmpg_set_header(struct bch_nvmpg_ns *ns)
> +{
> + struct bch_nvmpg_set_header *set_header;
> +
> + if (ns->ns_id != 0) {
> + pr_err("unexpected ns_id %u for first nvmpg namespace.\n",
> + ns->ns_id);
> + return -EINVAL;
> + }
> +
> + set_header = bch_nvmpg_offset_to_ptr(ns->sb->set_header_offset);
> +
> + mutex_lock(&global_nvmpg_set->lock);
> + global_nvmpg_set->set_header = set_header;
> + global_nvmpg_set->heads_size = set_header->size;
> + global_nvmpg_set->heads_used = set_header->used;
> + mutex_unlock(&global_nvmpg_set->lock);
> +
> + return 0;
> +}
> +
> +static int attach_nvmpg_set(struct bch_nvmpg_ns *ns)
> +{
> + struct bch_nvmpg_sb *sb = ns->sb;
> + int rc = 0;
> +
> + mutex_lock(&global_nvmpg_set->lock);
> +
> + if (global_nvmpg_set->ns_tbl[sb->this_ns]) {
> + pr_err("ns_id %u already attached.\n", ns->ns_id);
> + rc = -EEXIST;
> + goto unlock;
> + }
> +
> + if (ns->ns_id != 0) {
> + pr_err("unexpected ns_id %u for first namespace.\n", ns->ns_id);
> + rc = -EINVAL;
> + goto unlock;
> + }
> +
> + if (global_nvmpg_set->attached_ns > 0) {
> + pr_err("multiple namespace attaching not supported yet\n");
> + rc = -EOPNOTSUPP;
> + goto unlock;
> + }
> +
> + if ((global_nvmpg_set->attached_ns + 1) > sb->total_ns) {
> + pr_err("namespace counters error: attached %u > total %u\n",
> + global_nvmpg_set->attached_ns,
> + global_nvmpg_set->total_ns);
> + rc = -EINVAL;
> + goto unlock;
> + }
> +
> + memcpy(global_nvmpg_set->set_uuid, sb->set_uuid, 16);
> + global_nvmpg_set->ns_tbl[sb->this_ns] = ns;
> + global_nvmpg_set->attached_ns++;
> + global_nvmpg_set->total_ns = sb->total_ns;
> +
> +unlock:
> + mutex_unlock(&global_nvmpg_set->lock);
> + return rc;
> +}
> +
> +static int read_nvdimm_meta_super(struct block_device *bdev,
> + struct bch_nvmpg_ns *ns)
> +{
> + struct page *page;
> + struct bch_nvmpg_sb *sb;
> + uint64_t expected_csum = 0;
> + int r;
> +
> + page = read_cache_page_gfp(bdev->bd_inode->i_mapping,
> + BCH_NVMPG_SB_OFFSET >> PAGE_SHIFT, GFP_KERNEL);
> +
> + if (IS_ERR(page))
> + return -EIO;
> +
> + sb = (struct bch_nvmpg_sb *)
> + (page_address(page) + offset_in_page(BCH_NVMPG_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_nvmpg_magic, 16)) {
> + pr_info("invalid bch_nvmpg_magic\n");
> + goto put_page;
> + }
> +
> + if (sb->sb_offset !=
> + BCH_NVMPG_OFFSET(sb->this_ns, BCH_NVMPG_SB_OFFSET)) {
> + pr_info("invalid superblock offset 0x%llx\n", sb->sb_offset);
> + goto put_page;
> + }
> +
> + r = -EOPNOTSUPP;
> + if (sb->total_ns != 1) {
> + pr_info("multiple name space not supported yet.\n");
> + goto put_page;
> + }
> +
> +
> + r = 0;
> + /* Necessary for DAX mapping */
> + ns->page_size = sb->page_size;
> + ns->pages_total = sb->pages_total;
> +
> +put_page:
> + put_page(page);
> + return r;
> +}
> +
> +struct bch_nvmpg_ns *bch_register_namespace(const char *dev_path)
> +{
> + struct bch_nvmpg_ns *ns = NULL;
> + struct bch_nvmpg_sb *sb = NULL;
> + char buf[BDEVNAME_SIZE];
> + struct block_device *bdev;
> + pgoff_t pgoff;
> + int id, err;
> + char *path;
> + long dax_ret = 0;
> +
> + 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,
> + global_nvmpg_set);
> + if (IS_ERR(bdev)) {
> + pr_err("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_nvmpg_ns), GFP_KERNEL);
> + if (!ns)
> + goto bdput;
> +
> + err = -EIO;
> + if (read_nvdimm_meta_super(bdev, ns)) {
> + pr_err("%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_err("%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_err("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_err("can't by dax device by %s\n", bdevname(bdev, buf));
> + goto free_ns;
> + }
> +
> + err = -EINVAL;
> + id = dax_read_lock();
> + dax_ret = dax_direct_access(ns->dax_dev, pgoff, ns->pages_total,
> + &ns->base_addr, &ns->start_pfn);
> + if (dax_ret <= 0) {
> + pr_err("dax_direct_access error\n");
> + dax_read_unlock(id);
> + goto free_ns;
> + }
> +
> + if (dax_ret < ns->pages_total) {
> + pr_warn("mapped range %ld is less than ns->pages_total %lu\n",
> + dax_ret, ns->pages_total);
This failure will become a common occurrence with CXL namespaces that
will have discontiguous range support. It's already the case for
dax-devices for soft-reserved memory [1]. In the CXL case the
discontinuity will be 256MB aligned, for the soft-reserved dax-devices
the discontinuity granularity can be as small as 4K.
[1]: https://elixir.bootlin.com/linux/v5.14-rc5/source/drivers/dax/device.c#L414
