nilfs2: add routines to save and restore bmap state

This adds routines to save and restore the state of bmap structure.
The bmap state is stored in a given nilfs_bmap_store object.

These routines will be used to roll back the state of dat inode
without using gcdat inode.

Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>

1 files changed, 8 insertions, 0 deletions

diff --git a/fs/nilfs2/bmap.h b/fs/nilfs2/bmap.h
index a20569b19929..5f3339e3eac9 100644
--- a/fs/nilfs2/bmap.h
+++ b/fs/nilfs2/bmap.h
@@ -135,6 +135,12 @@ struct nilfs_bmap {
 /* state */
 #define NILFS_BMAP_DIRTY        0x00000001
 
+struct nilfs_bmap_store {
+        __le64 data[NILFS_BMAP_SIZE / sizeof(__le64)];
+        __u64 last_allocated_key;
+        __u64 last_allocated_ptr;
+        int state;
+};
 
 int nilfs_bmap_test_and_clear_dirty(struct nilfs_bmap *);
 int nilfs_bmap_read(struct nilfs_bmap *, struct nilfs_inode *);
@@ -156,6 +162,8 @@ void nilfs_bmap_init_gc(struct nilfs_bmap *);
 void nilfs_bmap_init_gcdat(struct nilfs_bmap *, struct nilfs_bmap *);
 void nilfs_bmap_commit_gcdat(struct nilfs_bmap *, struct nilfs_bmap *);
 
+void nilfs_bmap_save(const struct nilfs_bmap *, struct nilfs_bmap_store *);
+void nilfs_bmap_restore(struct nilfs_bmap *, const struct nilfs_bmap_store *);
 
 static inline int nilfs_bmap_lookup(struct nilfs_bmap *bmap, __u64 key,
                                     __u64 *ptr)