[PATCH 3/8] nilfs2: embed a back pointer to super block instance in nilfs object

[Ryusuke Konishi]

Insert a back pointer to super block instance in nilfs object so that
functions of nilfs2 easily refer to the super block instance.  This
simplifies replacement of printk() in the successive change.

Signed-off-by: Ryusuke Konishi <konishi.ryus...@lab.ntt.co.jp>
---
 fs/nilfs2/super.c     | 2 +-
 fs/nilfs2/the_nilfs.c | 7 ++++---
 fs/nilfs2/the_nilfs.h | 4 +++-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index 86e3c00..2d4d0be 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -1076,7 +1076,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int 
silent)
        __u64 cno;
        int err;
 
-       nilfs = alloc_nilfs(sb->s_bdev);
+       nilfs = alloc_nilfs(sb);
        if (!nilfs)
                return -ENOMEM;
 
diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index 809bd2d..dbead89 100644
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -56,12 +56,12 @@ void nilfs_set_last_segment(struct the_nilfs *nilfs,
 
 /**
  * alloc_nilfs - allocate a nilfs object
- * @bdev: block device to which the_nilfs is related
+ * @sb: super block instance
  *
  * Return Value: On success, pointer to the_nilfs is returned.
  * On error, NULL is returned.
  */
-struct the_nilfs *alloc_nilfs(struct block_device *bdev)
+struct the_nilfs *alloc_nilfs(struct super_block *sb)
 {
        struct the_nilfs *nilfs;
 
@@ -69,7 +69,8 @@ struct the_nilfs *alloc_nilfs(struct block_device *bdev)
        if (!nilfs)
                return NULL;
 
-       nilfs->ns_bdev = bdev;
+       nilfs->ns_sb = sb;
+       nilfs->ns_bdev = sb->s_bdev;
        atomic_set(&nilfs->ns_ndirtyblks, 0);
        init_rwsem(&nilfs->ns_sem);
        mutex_init(&nilfs->ns_snapshot_mount_mutex);
diff --git a/fs/nilfs2/the_nilfs.h b/fs/nilfs2/the_nilfs.h
index 79369fd..79d1421 100644
--- a/fs/nilfs2/the_nilfs.h
+++ b/fs/nilfs2/the_nilfs.h
@@ -43,6 +43,7 @@ enum {
  * struct the_nilfs - struct to supervise multiple nilfs mount points
  * @ns_flags: flags
  * @ns_flushed_device: flag indicating if all volatile data was flushed
+ * @ns_sb: back pointer to super block instance
  * @ns_bdev: block device
  * @ns_sem: semaphore for shared states
  * @ns_snapshot_mount_mutex: mutex to protect snapshot mounts
@@ -102,6 +103,7 @@ struct the_nilfs {
        unsigned long           ns_flags;
        int                     ns_flushed_device;
 
+       struct super_block     *ns_sb;
        struct block_device    *ns_bdev;
        struct rw_semaphore     ns_sem;
        struct mutex            ns_snapshot_mount_mutex;
@@ -281,7 +283,7 @@ static inline int nilfs_sb_will_flip(struct the_nilfs 
*nilfs)
 }
 
 void nilfs_set_last_segment(struct the_nilfs *, sector_t, u64, __u64);
-struct the_nilfs *alloc_nilfs(struct block_device *bdev);
+struct the_nilfs *alloc_nilfs(struct super_block *sb);
 void destroy_nilfs(struct the_nilfs *nilfs);
 int init_nilfs(struct the_nilfs *nilfs, struct super_block *sb, char *data);
 int load_nilfs(struct the_nilfs *nilfs, struct super_block *sb);
-- 
1.8.3.1