mm/balloon_compaction: remove balloon mapping and flag AS_BALLOON_MAP

Now ballooned pages are detected using PageBalloon().  Fake mapping is no
longer required.  This patch links ballooned pages to balloon device using
field page->private instead of page->mapping.  Also this patch embeds
balloon_dev_info directly into struct virtio_balloon.

Signed-off-by: Konstantin Khlebnikov <k.khlebnikov@samsung.com>
Cc: Rafael Aquini <aquini@redhat.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 6 insertions, 89 deletions

diff --git a/mm/balloon_compaction.c b/mm/balloon_compaction.c
index 52abeeb3cb9d..3afdabdbc0a4 100644
--- a/mm/balloon_compaction.c
+++ b/mm/balloon_compaction.c
@@ -11,32 +11,6 @@
 #include <linux/balloon_compaction.h>
 
 /*
- * balloon_devinfo_alloc - allocates a balloon device information descriptor.
- * @balloon_dev_descriptor: pointer to reference the balloon device which
- *                          this struct balloon_dev_info will be servicing.
- *
- * Driver must call it to properly allocate and initialize an instance of
- * struct balloon_dev_info which will be used to reference a balloon device
- * as well as to keep track of the balloon device page list.
- */
-struct balloon_dev_info *balloon_devinfo_alloc(void *balloon_dev_descriptor)
-{
-        struct balloon_dev_info *b_dev_info;
-        b_dev_info = kmalloc(sizeof(*b_dev_info), GFP_KERNEL);
-        if (!b_dev_info)
-                return ERR_PTR(-ENOMEM);
-
-        b_dev_info->balloon_device = balloon_dev_descriptor;
-        b_dev_info->mapping = NULL;
-        b_dev_info->isolated_pages = 0;
-        spin_lock_init(&b_dev_info->pages_lock);
-        INIT_LIST_HEAD(&b_dev_info->pages);
-
-        return b_dev_info;
-}
-EXPORT_SYMBOL_GPL(balloon_devinfo_alloc);
-
-/*
  * balloon_page_enqueue - allocates a new page and inserts it into the balloon
  *                        page list.
  * @b_dev_info: balloon device decriptor where we will insert a new page to
@@ -61,7 +35,7 @@ struct page *balloon_page_enqueue(struct balloon_dev_info *b_dev_info)
          */
         BUG_ON(!trylock_page(page));
         spin_lock_irqsave(&b_dev_info->pages_lock, flags);
-        balloon_page_insert(page, b_dev_info->mapping, &b_dev_info->pages);
+        balloon_page_insert(b_dev_info, page);
         spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
         unlock_page(page);
         return page;
@@ -127,60 +101,10 @@ struct page *balloon_page_dequeue(struct balloon_dev_info *b_dev_info)
 EXPORT_SYMBOL_GPL(balloon_page_dequeue);
 
 #ifdef CONFIG_BALLOON_COMPACTION
-/*
- * balloon_mapping_alloc - allocates a special ->mapping for ballooned pages.
- * @b_dev_info: holds the balloon device information descriptor.
- * @a_ops: balloon_mapping address_space_operations descriptor.
- *
- * Driver must call it to properly allocate and initialize an instance of
- * struct address_space which will be used as the special page->mapping for
- * balloon device enlisted page instances.
- */
-struct address_space *balloon_mapping_alloc(struct balloon_dev_info *b_dev_info,
-                                const struct address_space_operations *a_ops)
-{
-        struct address_space *mapping;
-
-        mapping = kmalloc(sizeof(*mapping), GFP_KERNEL);
-        if (!mapping)
-                return ERR_PTR(-ENOMEM);
-
-        /*
-         * Give a clean 'zeroed' status to all elements of this special
-         * balloon page->mapping struct address_space instance.
-         */
-        address_space_init_once(mapping);
-
-        /*
-         * Set mapping->flags appropriately, to allow balloon pages
-         * ->mapping identification.
-         */
-        mapping_set_balloon(mapping);
-        mapping_set_gfp_mask(mapping, balloon_mapping_gfp_mask());
-
-        /* balloon's page->mapping->a_ops callback descriptor */
-        mapping->a_ops = a_ops;
-
-        /*
-         * Establish a pointer reference back to the balloon device descriptor
-         * this particular page->mapping will be servicing.
-         * This is used by compaction / migration procedures to identify and
-         * access the balloon device pageset while isolating / migrating pages.
-         *
-         * As some balloon drivers can register multiple balloon devices
-         * for a single guest, this also helps compaction / migration to
-         * properly deal with multiple balloon pagesets, when required.
-         */
-        mapping->private_data = b_dev_info;
-        b_dev_info->mapping = mapping;
-
-        return mapping;
-}
-EXPORT_SYMBOL_GPL(balloon_mapping_alloc);
 
 static inline void __isolate_balloon_page(struct page *page)
 {
-        struct balloon_dev_info *b_dev_info = page->mapping->private_data;
+        struct balloon_dev_info *b_dev_info = balloon_page_device(page);
         unsigned long flags;
 
         spin_lock_irqsave(&b_dev_info->pages_lock, flags);
@@ -192,7 +116,7 @@ static inline void __isolate_balloon_page(struct page *page)
 
 static inline void __putback_balloon_page(struct page *page)
 {
-        struct balloon_dev_info *b_dev_info = page->mapping->private_data;
+        struct balloon_dev_info *b_dev_info = balloon_page_device(page);
         unsigned long flags;
 
         spin_lock_irqsave(&b_dev_info->pages_lock, flags);
@@ -202,12 +126,6 @@ static inline void __putback_balloon_page(struct page *page)
         spin_unlock_irqrestore(&b_dev_info->pages_lock, flags);
 }
 
-static inline int __migrate_balloon_page(struct address_space *mapping,
-                struct page *newpage, struct page *page, enum migrate_mode mode)
-{
-        return page->mapping->a_ops->migratepage(mapping, newpage, page, mode);
-}
-
 /* __isolate_lru_page() counterpart for a ballooned page */
 bool balloon_page_isolate(struct page *page)
 {
@@ -274,7 +192,7 @@ void balloon_page_putback(struct page *page)
 int balloon_page_migrate(struct page *newpage,
                          struct page *page, enum migrate_mode mode)
 {
-        struct address_space *mapping;
+        struct balloon_dev_info *balloon = balloon_page_device(page);
         int rc = -EAGAIN;
 
         /*
@@ -290,9 +208,8 @@ int balloon_page_migrate(struct page *newpage,
                 return rc;
         }
 
-        mapping = page->mapping;
-        if (mapping)
-                rc = __migrate_balloon_page(mapping, newpage, page, mode);
+        if (balloon && balloon->migratepage)
+                rc = balloon->migratepage(balloon, newpage, page, mode);
 
         unlock_page(newpage);
         return rc;