Re: [PATCH 1/3] [FIX] hugetlb: Fix broken fs quota management

["Ken Chen" <kenchen@google.com>]

On 10/24/07, Dave Hansen <haveblue@us.ibm.com> wrote:
> But, I think what I'm realizing is that the free paths for shared vs.
> private are actually quite distinct.  Even more now after your patches
> abolish using and actual put_page() (and the destructors) on private
> pages losing their last mapping.
>
> I think it may make a lot of sense to have
> {alloc,free}_{private,shared}_huge_page().  It'll really help
> readability, and I _think_ it gives you a handy dandy place to add the
> different quota operations needed.

Here is my version of re-factoring hugetlb_put_quota() into
free_huge_page.  Not exactly what Dave suggested, but at least
consolidate quota credit in one place.


diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index 12aca8e..6513f56 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -364,7 +364,6 @@ static void truncate_hugepages(
 			++next;
 			truncate_huge_page(page);
 			unlock_page(page);
-			hugetlb_put_quota(mapping);
 			freed++;
 		}
 		huge_pagevec_release(&pvec);
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 8b809ec..70c58cd 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -116,6 +116,9 @@
  static void free_huge_page(struct page *page)
 {
  	int nid = page_to_nid(page);
+	struct address_space *mapping;
+
+	mapping = (struct address_space *) page_private(page);

 	BUG_ON(page_count(page));
  	INIT_LIST_HEAD(&page->lru);
@@ -129,6 +132,9 @@ static void free_huge_page(struct page *page)
 		enqueue_huge_page(page);
 	}
 	spin_unlock(&hugetlb_lock);
+	if (mapping)
+		hugetlb_put_quota(mapping);
+	set_page_private(page, 0);
 }

 /*
@@ -369,6 +375,7 @@ static struct page *alloc_huge_page(

 	spin_unlock(&hugetlb_lock);
 	set_page_refcounted(page);
+	set_page_private(page, (unsigned long) vma->vm_file->f_mapping);
 	return page;

 fail:
@@ -382,6 +389,8 @@ fail:
 	if (!use_reserved_page)
  		page = alloc_buddy_huge_page(vma, addr);

+	if (page)
+		set_page_private(page, (unsigned long) vma->vm_file->f_mapping);
 	return page;
 }

@@ -788,7 +797,6 @@ retry:
  			err = add_to_page_cache(page, mapping, idx, GFP_KERNEL);
 			if (err) {
 				put_page(page);
-				hugetlb_put_quota(mapping);
  				if (err == -EEXIST)
  					goto retry;
  				goto out;
@@ -822,7 +830,6 @@ out:

  backout:
 	spin_unlock(&mm->page_table_lock);
-	hugetlb_put_quota(mapping);
 	unlock_page(page);
 	put_page(page);
  	goto out;

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