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[PATCH] page migration cleanup: drop nr_refs in remove_references()

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Drop nr_refs parameter from migrate_page_remove_references()

The nr_refs parameter is not really useful since the number of remaining
references is always

1 for anonymous pages without a mapping
2 for pages with a mapping
3 for pages with a mapping and PagePrivate set.

Remove the early check for the number of references since we are checking
page_mapcount() earlier.  Ultimately only the refcount matters after the
tree_lock has been obtained.

Signed-off-by: Christoph Lameter <clameter@sgi.coim>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This commit is contained in:
Christoph Lameter 2006-06-23 02:03:29 -07:00 committed by Linus Torvalds
parent e7340f7330
commit 5b5c7120e2
1 changed files with 11 additions and 10 deletions
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21
mm/migrate.c
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@ -168,19 +168,19 @@ static int swap_page(struct page *page)
/*
* Remove references for a page and establish the new page with the correct
* basic settings to be able to stop accesses to the page.
*
* The number of remaining references must be:
* 1 for anonymous pages without a mapping
* 2 for pages with a mapping
* 3 for pages with a mapping and PagePrivate set.
*/
static int migrate_page_remove_references(struct page *newpage,
struct page *page, int nr_refs)
struct page *page)
{
struct address_space *mapping = page_mapping(page);
struct page **radix_pointer;
/*
* Avoid doing any of the following work if the page count
* indicates that the page is in use or truncate has removed
* the page.
*/
if (!mapping || page_mapcount(page) + nr_refs != page_count(page))
if (!mapping)
return -EAGAIN;
/*
@ -218,7 +218,8 @@ static int migrate_page_remove_references(struct page *newpage,
&mapping->page_tree,
page_index(page));
if (!page_mapping(page) || page_count(page) != nr_refs ||
if (!page_mapping(page) ||
page_count(page) != 2 + !!PagePrivate(page) ||
*radix_pointer != page) {
write_unlock_irq(&mapping->tree_lock);
return -EAGAIN;
@ -309,7 +310,7 @@ int migrate_page(struct page *newpage, struct page *page)
BUG_ON(PageWriteback(page)); /* Writeback must be complete */
rc = migrate_page_remove_references(newpage, page, 2);
rc = migrate_page_remove_references(newpage, page);
if (rc)
return rc;
@ -348,7 +349,7 @@ int buffer_migrate_page(struct page *newpage, struct page *page)
head = page_buffers(page);
rc = migrate_page_remove_references(newpage, page, 3);
rc = migrate_page_remove_references(newpage, page);
if (rc)
return rc;