nilfs2: get rid of nilfs_sb_info structure

This directly uses sb->s_fs_info to keep a nilfs filesystem object and
fully removes the intermediate nilfs_sb_info structure.  With this
change, the hierarchy of on-memory structures of nilfs will be
simplified as follows:

Before:
  super_block
       -> nilfs_sb_info
             -> the_nilfs
                   -> cptree --+-> nilfs_root (current file system)
                               +-> nilfs_root (snapshot A)
                               +-> nilfs_root (snapshot B)
                               :
             -> nilfs_sc_info (log writer structure)
After:
  super_block
       -> the_nilfs
             -> cptree --+-> nilfs_root (current file system)
                         +-> nilfs_root (snapshot A)
                         +-> nilfs_root (snapshot B)
                         :
             -> nilfs_sc_info (log writer structure)

The reason why we didn't design so from the beginning is because the
initial shape also differed from the above.  The early hierachy was
composed of "per-mount-point" super_block -> nilfs_sb_info pairs and a
shared nilfs object.  On the kernel 2.6.37, it was changed to the
current shape in order to unify super block instances into one per
device, and this cleanup became applicable as the result.

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

1 files changed, 23 insertions, 40 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index a8cbd695441..062cca06519 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -76,7 +76,7 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data);
 
 static void nilfs_set_error(struct super_block *sb)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_super_block **sbp;
 
 	down_write(&nilfs->ns_sem);
@@ -108,7 +108,7 @@ static void nilfs_set_error(struct super_block *sb)
 void nilfs_error(struct super_block *sb, const char *function,
 		 const char *fmt, ...)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct va_format vaf;
 	va_list args;
 
@@ -190,7 +190,7 @@ void nilfs_destroy_inode(struct inode *inode)
 
 static int nilfs_sync_super(struct super_block *sb, int flag)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	int err;
 
  retry:
@@ -265,7 +265,7 @@ void nilfs_set_log_cursor(struct nilfs_super_block *sbp,
 struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
 					       int flip)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
 
 	/* nilfs->ns_sem must be locked by the caller. */
@@ -291,7 +291,7 @@ struct nilfs_super_block **nilfs_prepare_super(struct super_block *sb,
 
 int nilfs_commit_super(struct super_block *sb, int flag)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_super_block **sbp = nilfs->ns_sbp;
 	time_t t;
 
@@ -324,7 +324,7 @@ int nilfs_commit_super(struct super_block *sb, int flag)
  */
 int nilfs_cleanup_super(struct super_block *sb)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_super_block **sbp;
 	int flag = NILFS_SB_COMMIT;
 	int ret = -EIO;
@@ -349,8 +349,7 @@ int nilfs_cleanup_super(struct super_block *sb)
 
 static void nilfs_put_super(struct super_block *sb)
 {
-	struct nilfs_sb_info *sbi = NILFS_SB(sb);
-	struct the_nilfs *nilfs = sbi->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 
 	nilfs_detach_log_writer(sb);
 
@@ -365,14 +364,12 @@ static void nilfs_put_super(struct super_block *sb)
 	iput(nilfs->ns_dat);
 
 	destroy_nilfs(nilfs);
-	sbi->s_super = NULL;
 	sb->s_fs_info = NULL;
-	kfree(sbi);
 }
 
 static int nilfs_sync_fs(struct super_block *sb, int wait)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_super_block **sbp;
 	int err = 0;
 
@@ -396,7 +393,7 @@ static int nilfs_sync_fs(struct super_block *sb, int wait)
 int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
 			    struct nilfs_root **rootp)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_root *root;
 	struct nilfs_checkpoint *raw_cp;
 	struct buffer_head *bh_cp;
@@ -449,7 +446,7 @@ int nilfs_attach_checkpoint(struct super_block *sb, __u64 cno, int curr_mnt,
 
 static int nilfs_freeze(struct super_block *sb)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	int err;
 
 	if (sb->s_flags & MS_RDONLY)
@@ -464,7 +461,7 @@ static int nilfs_freeze(struct super_block *sb)
 
 static int nilfs_unfreeze(struct super_block *sb)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 
 	if (sb->s_flags & MS_RDONLY)
 		return 0;
@@ -527,7 +524,7 @@ static int nilfs_statfs(struct dentry *dentry, struct kstatfs *buf)
 static int nilfs_show_options(struct seq_file *seq, struct vfsmount *vfs)
 {
 	struct super_block *sb = vfs->mnt_sb;
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_root *root = NILFS_I(vfs->mnt_root->d_inode)->i_root;
 
 	if (!nilfs_test_opt(nilfs, BARRIER))
@@ -591,7 +588,7 @@ static match_table_t tokens = {
 
 static int parse_options(char *options, struct super_block *sb, int is_remount)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	char *p;
 	substring_t args[MAX_OPT_ARGS];
 
@@ -660,7 +657,7 @@ static inline void
 nilfs_set_default_options(struct super_block *sb,
 			  struct nilfs_super_block *sbp)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 
 	nilfs->ns_mount_opt =
 		NILFS_MOUNT_ERRORS_RO | NILFS_MOUNT_BARRIER;
@@ -668,7 +665,7 @@ nilfs_set_default_options(struct super_block *sb,
 
 static int nilfs_setup_super(struct super_block *sb, int is_mount)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_super_block **sbp;
 	int max_mnt_count;
 	int mnt_count;
@@ -726,7 +723,7 @@ int nilfs_store_magic_and_option(struct super_block *sb,
 				 struct nilfs_super_block *sbp,
 				 char *data)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 
 	sb->s_magic = le16_to_cpu(sbp->s_magic);
 
@@ -821,7 +818,7 @@ static int nilfs_get_root_dentry(struct super_block *sb,
 static int nilfs_attach_snapshot(struct super_block *s, __u64 cno,
 				 struct dentry **root_dentry)
 {
-	struct the_nilfs *nilfs = NILFS_SB(s)->s_nilfs;
+	struct the_nilfs *nilfs = s->s_fs_info;
 	struct nilfs_root *root;
 	int ret;
 
@@ -873,7 +870,7 @@ static int nilfs_try_to_shrink_tree(struct dentry *root_dentry)
 
 int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	struct nilfs_root *root;
 	struct inode *inode;
 	struct dentry *dentry;
@@ -886,7 +883,7 @@ int nilfs_checkpoint_is_mounted(struct super_block *sb, __u64 cno)
 		return true;	/* protect recent checkpoints */
 
 	ret = false;
-	root = nilfs_lookup_root(NILFS_SB(sb)->s_nilfs, cno);
+	root = nilfs_lookup_root(nilfs, cno);
 	if (root) {
 		inode = nilfs_ilookup(sb, root, NILFS_ROOT_INO);
 		if (inode) {
@@ -916,25 +913,16 @@ static int
 nilfs_fill_super(struct super_block *sb, void *data, int silent)
 {
 	struct the_nilfs *nilfs;
-	struct nilfs_sb_info *sbi;
 	struct nilfs_root *fsroot;
 	struct backing_dev_info *bdi;
 	__u64 cno;
 	int err;
 
-	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
-	if (!sbi)
+	nilfs = alloc_nilfs(sb->s_bdev);
+	if (!nilfs)
 		return -ENOMEM;
 
-	sb->s_fs_info = sbi;
-	sbi->s_super = sb;
-
-	nilfs = alloc_nilfs(sb->s_bdev);
-	if (!nilfs) {
-		err = -ENOMEM;
-		goto failed_sbi;
-	}
-	sbi->s_nilfs = nilfs;
+	sb->s_fs_info = nilfs;
 
 	err = init_nilfs(nilfs, sb, (char *)data);
 	if (err)
@@ -993,16 +981,12 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent)
 
  failed_nilfs:
 	destroy_nilfs(nilfs);
-
- failed_sbi:
-	sb->s_fs_info = NULL;
-	kfree(sbi);
 	return err;
 }
 
 static int nilfs_remount(struct super_block *sb, int *flags, char *data)
 {
-	struct the_nilfs *nilfs = NILFS_SB(sb)->s_nilfs;
+	struct the_nilfs *nilfs = sb->s_fs_info;
 	unsigned long old_sb_flags;
 	unsigned long old_mount_opt;
 	int err;
@@ -1083,7 +1067,6 @@ static int nilfs_remount(struct super_block *sb, int *flags, char *data)
 
 struct nilfs_super_data {
 	struct block_device *bdev;
-	struct nilfs_sb_info *sbi;
 	__u64 cno;
 	int flags;
 };