Re: [PATCH v13 05/12] bcache: bch_nvmpg_free_pages() of the buddy allocator

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在 2021/12/13 1:05, Coly Li 写道:
From: Jianpeng Ma <jianpeng.ma@xxxxxxxxx>

This patch implements the bch_nvmpg_free_pages() of the buddy allocator.

The difference between this and page-buddy-free:
it need owner_uuid to free owner allocated pages, and must
persistent after free.

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/nvmpg.c | 164 ++++++++++++++++++++++++++++++++++++--
  drivers/md/bcache/nvmpg.h |   3 +
  2 files changed, 160 insertions(+), 7 deletions(-)

diff --git a/drivers/md/bcache/nvmpg.c b/drivers/md/bcache/nvmpg.c
index a920779eb548..8ce0c4389b42 100644
--- a/drivers/md/bcache/nvmpg.c
+++ b/drivers/md/bcache/nvmpg.c
@@ -248,6 +248,57 @@ static int init_nvmpg_set_header(struct bch_nvmpg_ns *ns)
  	return rc;
  }
+static void __free_space(struct bch_nvmpg_ns *ns, unsigned long nvmpg_offset,
+			 int order)
+{
+	unsigned long add_pages = (1L << order);
+	pgoff_t pgoff;
+	struct page *page;
+	void *va;
+
+	if (nvmpg_offset == 0) {
+		pr_err("free pages on offset 0\n");
+		return;
+	}
+
+	page = bch_nvmpg_va_to_pg(bch_nvmpg_offset_to_ptr(nvmpg_offset));
+	WARN_ON((!page) || (page->private != order));
+	pgoff = page->index;
+
+	while (order < BCH_MAX_ORDER - 1) {
+		struct page *buddy_page;
+
+		pgoff_t buddy_pgoff = pgoff ^ (1L << order);
+		pgoff_t parent_pgoff = pgoff & ~(1L << order);
+
+		if ((parent_pgoff + (1L << (order + 1)) > ns->pages_total))
+			break;
+
+		va = bch_nvmpg_pgoff_to_ptr(ns, buddy_pgoff);
+		buddy_page = bch_nvmpg_va_to_pg(va);
+		WARN_ON(!buddy_page);
+
+		if (PageBuddy(buddy_page) && (buddy_page->private == order)) {
+			list_del((struct list_head *)&buddy_page->zone_device_data);
+			__ClearPageBuddy(buddy_page);
+			pgoff = parent_pgoff;
+			order++;
+			continue;
+		}
+		break;
+	}
+
+	va = bch_nvmpg_pgoff_to_ptr(ns, pgoff);
+	page = bch_nvmpg_va_to_pg(va);
+	WARN_ON(!page);
+	list_add((struct list_head *)&page->zone_device_data,
+		 &ns->free_area[order]);
+	page->index = pgoff;
+	set_page_private(page, order);
+	__SetPageBuddy(page);
+	ns->free += add_pages;
+}
+
  static void bch_nvmpg_init_free_space(struct bch_nvmpg_ns *ns)
  {
  	unsigned int start, end, pages;
@@ -261,21 +312,19 @@ static void bch_nvmpg_init_free_space(struct bch_nvmpg_ns *ns)
  		pages = end - start;
while (pages) {
-			void *addr;
-
  			for (i = BCH_MAX_ORDER - 1; i >= 0; i--) {
  				if ((pgoff_start % (1L << i) == 0) &&
  				    (pages >= (1L << i)))
  					break;
  			}
- addr = bch_nvmpg_pgoff_to_ptr(ns, pgoff_start);
-			page = bch_nvmpg_va_to_pg(addr);
+			page = bch_nvmpg_va_to_pg(
+					bch_nvmpg_pgoff_to_ptr(ns, pgoff_start));
  			set_page_private(page, i);
  			page->index = pgoff_start;
-			__SetPageBuddy(page);
-			list_add((struct list_head *)&page->zone_device_data,
-				 &ns->free_area[i]);
+
+			/* In order to update ns->free */
+			__free_space(ns, pgoff_start, i);

Hi,

While testing this patchset, we found that this is probably wrong,
pgoff_start represent page number here, however, __free_space expect
this to be page offset. Maybe this should be:

__free_space(ns, pgoff_start << PAGE_SHIFT, i);

Thanks,
Kuai



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