return count;
}
-/*
- * Non migratable page
- */
-int fail_migrate_page(struct page *newpage, struct page *page)
-{
- return -EIO;
-}
-EXPORT_SYMBOL(fail_migrate_page);
-
/*
* swapout a single page
* page is locked upon entry, unlocked on exit
}
/*
- * Remove references for a page and establish the new page with the correct
- * basic settings to be able to stop accesses to the page.
+ * Replace the page in the mapping.
+ *
+ * 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.
*/
-int migrate_page_remove_references(struct page *newpage,
- struct page *page, int nr_refs)
+static int migrate_page_move_mapping(struct page *newpage,
+ 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))
- return -EAGAIN;
-
- /*
- * Establish swap ptes for anonymous pages or destroy pte
- * maps for files.
- *
- * In order to reestablish file backed mappings the fault handlers
- * will take the radix tree_lock which may then be used to stop
- * processses from accessing this page until the new page is ready.
- *
- * A process accessing via a swap pte (an anonymous page) will take a
- * page_lock on the old page which will block the process until the
- * migration attempt is complete. At that time the PageSwapCache bit
- * will be examined. If the page was migrated then the PageSwapCache
- * bit will be clear and the operation to retrieve the page will be
- * retried which will find the new page in the radix tree. Then a new
- * direct mapping may be generated based on the radix tree contents.
- *
- * If the page was not migrated then the PageSwapCache bit
- * is still set and the operation may continue.
- */
- if (try_to_unmap(page, 1) == SWAP_FAIL)
- /* A vma has VM_LOCKED set -> permanent failure */
- return -EPERM;
-
- /*
- * Give up if we were unable to remove all mappings.
- */
- if (page_mapcount(page))
+ if (!mapping)
return -EAGAIN;
write_lock_irq(&mapping->tree_lock);
&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;
return 0;
}
-EXPORT_SYMBOL(migrate_page_remove_references);
/*
* Copy the page to its new location
*/
-void migrate_page_copy(struct page *newpage, struct page *page)
+static void migrate_page_copy(struct page *newpage, struct page *page)
{
copy_highpage(newpage, page);
if (PageWriteback(newpage))
end_page_writeback(newpage);
}
-EXPORT_SYMBOL(migrate_page_copy);
+
+/************************************************************
+ * Migration functions
+ ***********************************************************/
+
+/* Always fail migration. Used for mappings that are not movable */
+int fail_migrate_page(struct page *newpage, struct page *page)
+{
+ return -EIO;
+}
+EXPORT_SYMBOL(fail_migrate_page);
/*
* Common logic to directly migrate a single page suitable for
BUG_ON(PageWriteback(page)); /* Writeback must be complete */
- rc = migrate_page_remove_references(newpage, page, 2);
+ rc = migrate_page_move_mapping(newpage, page);
if (rc)
return rc;
}
EXPORT_SYMBOL(migrate_page);
+/*
+ * Migration function for pages with buffers. This function can only be used
+ * if the underlying filesystem guarantees that no other references to "page"
+ * exist.
+ */
+int buffer_migrate_page(struct page *newpage, struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ struct buffer_head *bh, *head;
+ int rc;
+
+ if (!mapping)
+ return -EAGAIN;
+
+ if (!page_has_buffers(page))
+ return migrate_page(newpage, page);
+
+ head = page_buffers(page);
+
+ rc = migrate_page_move_mapping(newpage, page);
+
+ if (rc)
+ return rc;
+
+ bh = head;
+ do {
+ get_bh(bh);
+ lock_buffer(bh);
+ bh = bh->b_this_page;
+
+ } while (bh != head);
+
+ ClearPagePrivate(page);
+ set_page_private(newpage, page_private(page));
+ set_page_private(page, 0);
+ put_page(page);
+ get_page(newpage);
+
+ bh = head;
+ do {
+ set_bh_page(bh, newpage, bh_offset(bh));
+ bh = bh->b_this_page;
+
+ } while (bh != head);
+
+ SetPagePrivate(newpage);
+
+ migrate_page_copy(newpage, page);
+
+ bh = head;
+ do {
+ unlock_buffer(bh);
+ put_bh(bh);
+ bh = bh->b_this_page;
+
+ } while (bh != head);
+
+ return 0;
+}
+EXPORT_SYMBOL(buffer_migrate_page);
+
/*
* migrate_pages
*
newpage = lru_to_page(to);
lock_page(newpage);
+ /*
+ * Establish swap ptes for anonymous pages or destroy pte
+ * maps for files.
+ *
+ * In order to reestablish file backed mappings the fault handlers
+ * will take the radix tree_lock which may then be used to stop
+ * processses from accessing this page until the new page is ready.
+ *
+ * A process accessing via a swap pte (an anonymous page) will take a
+ * page_lock on the old page which will block the process until the
+ * migration attempt is complete. At that time the PageSwapCache bit
+ * will be examined. If the page was migrated then the PageSwapCache
+ * bit will be clear and the operation to retrieve the page will be
+ * retried which will find the new page in the radix tree. Then a new
+ * direct mapping may be generated based on the radix tree contents.
+ *
+ * If the page was not migrated then the PageSwapCache bit
+ * is still set and the operation may continue.
+ */
+ rc = -EPERM;
+ if (try_to_unmap(page, 1) == SWAP_FAIL)
+ /* A vma has VM_LOCKED set -> permanent failure */
+ goto unlock_both;
+
+ rc = -EAGAIN;
+ if (page_mapped(page))
+ goto unlock_both;
/*
* Pages are properly locked and writeback is complete.
* Try to migrate the page.
goto unlock_both;
}
- /* Make sure the dirty bit is up to date */
- if (try_to_unmap(page, 1) == SWAP_FAIL) {
- rc = -EPERM;
- goto unlock_both;
- }
-
- if (page_mapcount(page)) {
- rc = -EAGAIN;
- goto unlock_both;
- }
-
/*
* Default handling if a filesystem does not provide
* a migration function. We can only migrate clean
return nr_failed + retry;
}
-/*
- * Migration function for pages with buffers. This function can only be used
- * if the underlying filesystem guarantees that no other references to "page"
- * exist.
- */
-int buffer_migrate_page(struct page *newpage, struct page *page)
-{
- struct address_space *mapping = page->mapping;
- struct buffer_head *bh, *head;
- int rc;
-
- if (!mapping)
- return -EAGAIN;
-
- if (!page_has_buffers(page))
- return migrate_page(newpage, page);
-
- head = page_buffers(page);
-
- rc = migrate_page_remove_references(newpage, page, 3);
-
- if (rc)
- return rc;
-
- bh = head;
- do {
- get_bh(bh);
- lock_buffer(bh);
- bh = bh->b_this_page;
-
- } while (bh != head);
-
- ClearPagePrivate(page);
- set_page_private(newpage, page_private(page));
- set_page_private(page, 0);
- put_page(page);
- get_page(newpage);
-
- bh = head;
- do {
- set_bh_page(bh, newpage, bh_offset(bh));
- bh = bh->b_this_page;
-
- } while (bh != head);
-
- SetPagePrivate(newpage);
-
- migrate_page_copy(newpage, page);
-
- bh = head;
- do {
- unlock_buffer(bh);
- put_bh(bh);
- bh = bh->b_this_page;
-
- } while (bh != head);
-
- return 0;
-}
-EXPORT_SYMBOL(buffer_migrate_page);
-
/*
* Migrate the list 'pagelist' of pages to a certain destination.
*
projects / linux-2.6-omap-h63xx.git / blobdiff