btrfs: support subpage for extent buffer page release

[linux-2.6-microblaze.git] / fs / btrfs / subpage.h

diff --git a/fs/btrfs/subpage.h b/fs/btrfs/subpage.h
index 7ba544b..fe51cc2 100644 (file)
--- a/fs/btrfs/subpage.h
+++ b/fs/btrfs/subpage.h
@@ -19,7 +19,13 @@ struct btrfs_subpage {
        /* Common members for both data and metadata pages */
        spinlock_t lock;
        union {
-               /* Structures only used by metadata */
+               /*
+                * Structures only used by metadata
+                *
+                * @eb_refs should only be operated under private_lock, as it
+                * manages whether the subpage can be detached.
+                */
+               atomic_t eb_refs;
                /* Structures only used by data */
        };
 };
@@ -40,4 +46,9 @@ int btrfs_alloc_subpage(const struct btrfs_fs_info *fs_info,
                        enum btrfs_subpage_type type);
 void btrfs_free_subpage(struct btrfs_subpage *subpage);
 
+void btrfs_page_inc_eb_refs(const struct btrfs_fs_info *fs_info,
+                           struct page *page);
+void btrfs_page_dec_eb_refs(const struct btrfs_fs_info *fs_info,
+                           struct page *page);
+
 #endif