From: Jianpeng Ma <[email protected]>

This nvm pages allocator will implement the simple buddy to manage the
nvm address space. This patch initializes this buddy for new namespace.

the unit of alloc/free of the buddy is page. DAX device has their
struct page(in dram or PMEM).

        struct {        /* ZONE_DEVICE pages */
                /** @pgmap: Points to the hosting device page map. */
                struct dev_pagemap *pgmap;
                void *zone_device_data;
                /*
                 * ZONE_DEVICE private pages are counted as being
                 * mapped so the next 3 words hold the mapping, index,
                 * and private fields from the source anonymous or
                 * page cache page while the page is migrated to device
                 * private memory.
                 * ZONE_DEVICE MEMORY_DEVICE_FS_DAX pages also
                 * use the mapping, index, and private fields when
                 * pmem backed DAX files are mapped.
                 */
        };

ZONE_DEVICE pages only use pgmap. Other 4 words[16/32 bytes] don't use.
So the second/third word will be used as 'struct list_head ' which list
in buddy. The fourth word(that is normal struct page::index) store pgoff
which the page-offset in the dax device. And the fifth word (that is
normal struct page::private) store order of buddy. page_type will be used
to store buddy flags.

Signed-off-by: Jianpeng Ma <[email protected]>
Co-authored-by: Qiaowei Ren <[email protected]>
---
 drivers/md/bcache/nvm-pages.c   | 142 +++++++++++++++++++++++++++++++-
 drivers/md/bcache/nvm-pages.h   |   6 ++
 include/uapi/linux/bcache-nvm.h |  12 ++-
 3 files changed, 153 insertions(+), 7 deletions(-)

diff --git a/drivers/md/bcache/nvm-pages.c b/drivers/md/bcache/nvm-pages.c
index 101b108b9766..fef497c7acb3 100644
--- a/drivers/md/bcache/nvm-pages.c
+++ b/drivers/md/bcache/nvm-pages.c
@@ -34,6 +34,10 @@ static void release_nvm_namespaces(struct bch_nvm_set 
*nvm_set)
        for (i = 0; i < nvm_set->total_namespaces_nr; i++) {
                ns = nvm_set->nss[i];
                if (ns) {
+                       kvfree(ns->pages_bitmap);
+                       if (ns->pgalloc_recs_bitmap)
+                               bitmap_free(ns->pgalloc_recs_bitmap);
+
                        blkdev_put(ns->bdev, FMODE_READ|FMODE_WRITE|FMODE_EXEC);
                        kfree(ns);
                }
@@ -48,17 +52,122 @@ static void release_nvm_set(struct bch_nvm_set *nvm_set)
        kfree(nvm_set);
 }
 
+static struct page *nvm_vaddr_to_page(struct bch_nvm_namespace *ns, void *addr)
+{
+       return virt_to_page(addr);
+}
+
+static void *nvm_pgoff_to_vaddr(struct bch_nvm_namespace *ns, pgoff_t pgoff)
+{
+       return ns->kaddr + (pgoff << PAGE_SHIFT);
+}
+
+static inline void remove_owner_space(struct bch_nvm_namespace *ns,
+                                       pgoff_t pgoff, u32 nr)
+{
+       bitmap_set(ns->pages_bitmap, pgoff, nr);
+}
+
 static int init_owner_info(struct bch_nvm_namespace *ns)
 {
        struct bch_owner_list_head *owner_list_head = ns->sb->owner_list_head;
+       struct bch_nvm_pgalloc_recs *sys_recs;
+       int i, j, k, rc = 0;
 
        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;
+
+       /*remove used space*/
+       remove_owner_space(ns, 0, ns->pages_offset/ns->page_size);
+
+       sys_recs = ns->kaddr + BCH_NVM_PAGES_SYS_RECS_HEAD_OFFSET;
+       // suppose no hole in array
+       for (i = 0; i < owner_list_head->used; i++) {
+               struct bch_nvm_pages_owner_head *head = 
&owner_list_head->heads[i];
+
+               for (j = 0; j < BCH_NVM_PAGES_NAMESPACES_MAX; j++) {
+                       struct bch_nvm_pgalloc_recs *pgalloc_recs = 
head->recs[j];
+                       unsigned long offset = (unsigned long)ns->kaddr >> 
PAGE_SHIFT;
+                       struct page *page;
+
+                       while (pgalloc_recs) {
+                               u32 pgalloc_recs_pos = (unsigned 
long)(pgalloc_recs - sys_recs);
+
+                               if (memcmp(pgalloc_recs->magic, 
bch_nvm_pages_pgalloc_magic, 16)) {
+                                       pr_info("invalid 
bch_nvm_pages_pgalloc_magic\n");
+                                       rc = -EINVAL;
+                                       goto unlock;
+                               }
+                               if (memcmp(pgalloc_recs->owner_uuid, 
head->uuid, 16)) {
+                                       pr_info("invalid owner_uuid in 
bch_nvm_pgalloc_recs\n");
+                                       rc = -EINVAL;
+                                       goto unlock;
+                               }
+                               if (pgalloc_recs->owner != head) {
+                                       pr_info("invalid owner in 
bch_nvm_pgalloc_recs\n");
+                                       rc = -EINVAL;
+                                       goto unlock;
+                               }
+
+                               // recs array can has hole
+                               for (k = 0; k < pgalloc_recs->size; k++) {
+                                       struct bch_pgalloc_rec *rec = 
&pgalloc_recs->recs[k];
+
+                                       if (rec->pgoff) {
+                                               BUG_ON(rec->pgoff <= offset);
+
+                                               /*init struct page: 
index/private */
+                                               page = nvm_vaddr_to_page(ns,
+                                                       
BCH_PGOFF_TO_KVADDR(rec->pgoff));
+
+                                               set_page_private(page, 
rec->order);
+                                               page->index = rec->pgoff - 
offset;
+
+                                               remove_owner_space(ns,
+                                                       rec->pgoff - offset,
+                                                       1 << rec->order);
+                                       }
+                               }
+                               bitmap_set(ns->pgalloc_recs_bitmap, 
pgalloc_recs_pos, 1);
+                               pgalloc_recs = pgalloc_recs->next;
+                       }
+               }
+       }
+unlock:
        mutex_unlock(&only_set->lock);
 
-       return 0;
+       return rc;
+}
+
+static void init_nvm_free_space(struct bch_nvm_namespace *ns)
+{
+       unsigned int start, end, i;
+       struct page *page;
+       long long pages;
+       pgoff_t pgoff_start;
+
+       bitmap_for_each_clear_region(ns->pages_bitmap, start, end, 0, 
ns->pages_total) {
+               pgoff_start = start;
+               pages = end - start;
+
+               while (pages) {
+                       for (i = BCH_MAX_ORDER - 1; i >= 0 ; i--) {
+                               if ((pgoff_start % (1 << i) == 0) && (pages >= 
(1 << i)))
+                                       break;
+                       }
+
+                       page = nvm_vaddr_to_page(ns, nvm_pgoff_to_vaddr(ns, 
pgoff_start));
+                       page->index = pgoff_start;
+                       set_page_private(page, i);
+                       __SetPageBuddy(page);
+                       list_add((struct list_head *)&page->zone_device_data, 
&ns->free_area[i]);
+
+                       pgoff_start += 1 << i;
+                       pages -= 1 << i;
+               }
+       }
 }
 
 static bool attach_nvm_set(struct bch_nvm_namespace *ns)
@@ -123,7 +232,7 @@ static int read_nvdimm_meta_super(struct block_device *bdev,
 struct bch_nvm_namespace *bch_register_namespace(const char *dev_path)
 {
        struct bch_nvm_namespace *ns;
-       int err;
+       int i, err;
        pgoff_t pgoff;
        char buf[BDEVNAME_SIZE];
        struct block_device *bdev;
@@ -238,18 +347,43 @@ struct bch_nvm_namespace *bch_register_namespace(const 
char *dev_path)
        ns->nvm_set = only_set;
        mutex_init(&ns->lock);
 
+       ns->pages_bitmap = kvcalloc(BITS_TO_LONGS(ns->pages_total),
+                                       sizeof(unsigned long), GFP_KERNEL);
+       if (!ns->pages_bitmap) {
+               err = -ENOMEM;
+               goto clear_ns_nr;
+       }
+
+       if (ns->sb->this_namespace_nr == 0) {
+               ns->pgalloc_recs_bitmap = bitmap_zalloc(BCH_MAX_PGALLOC_RECS, 
GFP_KERNEL);
+               if (ns->pgalloc_recs_bitmap == NULL) {
+                       err = -ENOMEM;
+                       goto free_pages_bitmap;
+               }
+       }
+
+       for (i = 0; i < BCH_MAX_ORDER; i++)
+               INIT_LIST_HEAD(&ns->free_area[i]);
+
        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;
+                       goto free_recs_bitmap;
                }
+               /* init buddy allocator */
+               init_nvm_free_space(ns);
        }
 
        kfree(path);
        return ns;
+free_recs_bitmap:
+       bitmap_free(ns->pgalloc_recs_bitmap);
+free_pages_bitmap:
+       kvfree(ns->pages_bitmap);
+clear_ns_nr:
+       only_set->nss[ns->sb->this_namespace_nr] = NULL;
 free_ns:
        kfree(ns);
 bdput:
diff --git a/drivers/md/bcache/nvm-pages.h b/drivers/md/bcache/nvm-pages.h
index 3b723a775b7b..c158033e24f0 100644
--- a/drivers/md/bcache/nvm-pages.h
+++ b/drivers/md/bcache/nvm-pages.h
@@ -14,6 +14,7 @@
  * to which owner. After reboot from power failure, they will be initialized
  * based on nvm pages superblock in NVDIMM device.
  */
+#define BCH_MAX_ORDER 20
 struct bch_nvm_namespace {
        struct bch_nvm_pages_sb *sb;
        void *kaddr;
@@ -25,6 +26,11 @@ struct bch_nvm_namespace {
        u64 pages_total;
        pfn_t start_pfn;
 
+       unsigned long *pages_bitmap;
+       struct list_head free_area[BCH_MAX_ORDER];
+
+       unsigned long *pgalloc_recs_bitmap;
+
        struct dax_device *dax_dev;
        struct block_device *bdev;
        struct bch_nvm_set *nvm_set;
diff --git a/include/uapi/linux/bcache-nvm.h b/include/uapi/linux/bcache-nvm.h
index 3c381c1b32ba..ec2626c418c6 100644
--- a/include/uapi/linux/bcache-nvm.h
+++ b/include/uapi/linux/bcache-nvm.h
@@ -117,6 +117,8 @@ struct bch_pgalloc_rec {
        __u64   reserved:6;
 };
 
+#define BCH_PGOFF_TO_KVADDR(pgoff) ((void *)((unsigned long)pgoff << 
PAGE_SHIFT))
+
 struct bch_nvm_pgalloc_recs {
 union {
        struct {
@@ -133,11 +135,15 @@ union {
 };
 };
 
-#define BCH_MAX_RECS                                   \
-       ((sizeof(struct bch_nvm_pgalloc_recs) -         \
-        offsetof(struct bch_nvm_pgalloc_recs, recs)) / \
+#define BCH_MAX_RECS                                                   \
+       ((sizeof(struct bch_nvm_pgalloc_recs) -                         \
+        offsetof(struct bch_nvm_pgalloc_recs, recs)) /                 \
         sizeof(struct bch_pgalloc_rec))
 
+#define BCH_MAX_PGALLOC_RECS                                           \
+       ((BCH_NVM_PAGES_OFFSET - BCH_NVM_PAGES_SYS_RECS_HEAD_OFFSET) /  \
+        sizeof(struct bch_nvm_pgalloc_recs))
+
 struct bch_nvm_pages_owner_head {
        unsigned char                   uuid[16];
        unsigned char                   label[BCH_NVM_PAGES_LABEL_SIZE];
-- 
2.26.2
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