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-rw-r--r--fs/buffer.c61
1 files changed, 61 insertions, 0 deletions
diff --git a/fs/buffer.c b/fs/buffer.c
index 3dc712f29d2..5e4a90ee103 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1022,6 +1022,7 @@ try_again:
bh->b_state = 0;
atomic_set(&bh->b_count, 0);
+ bh->b_private = NULL;
bh->b_size = size;
/* Link the buffer to its page */
@@ -3050,6 +3051,66 @@ asmlinkage long sys_bdflush(int func, long data)
}
/*
+ * Migration function for pages with buffers. This function can only be used
+ * if the underlying filesystem guarantees that no other references to "page"
+ * exist.
+ */
+#ifdef CONFIG_MIGRATION
+int buffer_migrate_page(struct page *newpage, struct page *page)
+{
+ struct address_space *mapping = page->mapping;
+ struct buffer_head *bh, *head;
+
+ if (!mapping)
+ return -EAGAIN;
+
+ if (!page_has_buffers(page))
+ return migrate_page(newpage, page);
+
+ head = page_buffers(page);
+
+ if (migrate_page_remove_references(newpage, page, 3))
+ return -EAGAIN;
+
+ 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);
+#endif
+
+/*
* Buffer-head allocation
*/
static kmem_cache_t *bh_cachep;