nilfs2: set pointer to root object in inodes

This puts a pointer to nilfs_root object in the private part of
on-memory inode, and makes nilfs_iget function pick up the inode with
the same root object.

Non-root inodes inherit its nilfs_root object from parent inode.  That
of the root inode is allocated through nilfs_attach_checkpoint()
function.

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

1 files changed, 30 insertions, 7 deletions

diff --git a/fs/nilfs2/super.c b/fs/nilfs2/super.c
index f3a00a3b2a03..a1c0e38a7706 100644
--- a/fs/nilfs2/super.c
+++ b/fs/nilfs2/super.c
@@ -391,18 +391,24 @@ static int nilfs_sync_fs(struct super_block *sb, int wait)
         return err;
 }
 
-int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno)
+int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno, int curr_mnt,
+                            struct nilfs_root **rootp)
 {
         struct the_nilfs *nilfs = sbi->s_nilfs;
+        struct nilfs_root *root;
         struct nilfs_checkpoint *raw_cp;
         struct buffer_head *bh_cp;
-        int err;
+        int err = -ENOMEM;
+
+        root = nilfs_find_or_create_root(
+                nilfs, curr_mnt ? NILFS_CPTREE_CURRENT_CNO : cno);
+        if (!root)
+                return err;
 
         down_write(&nilfs->ns_super_sem);
         list_add(&sbi->s_list, &nilfs->ns_supers);
         up_write(&nilfs->ns_super_sem);
 
-        err = -ENOMEM;
         sbi->s_ifile = nilfs_ifile_new(sbi, nilfs->ns_inode_size);
         if (!sbi->s_ifile)
                 goto delist;
@@ -428,6 +434,8 @@ int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno)
         atomic_set(&sbi->s_blocks_count, le64_to_cpu(raw_cp->cp_blocks_count));
 
         nilfs_cpfile_put_checkpoint(nilfs->ns_cpfile, cno, bh_cp);
+
+        *rootp = root;
         return 0;
 
  failed_bh:
@@ -440,6 +448,7 @@ int nilfs_attach_checkpoint(struct nilfs_sb_info *sbi, __u64 cno)
         down_write(&nilfs->ns_super_sem);
         list_del_init(&sbi->s_list);
         up_write(&nilfs->ns_super_sem);
+        nilfs_put_root(root);
 
         return err;
 }
@@ -551,12 +560,20 @@ static struct inode *
 nilfs_nfs_get_inode(struct super_block *sb, u64 ino, u32 generation)
 {
         struct inode *inode;
+        struct nilfs_root *root;
 
         if (ino < NILFS_FIRST_INO(sb) && ino != NILFS_ROOT_INO &&
             ino != NILFS_SKETCH_INO)
                 return ERR_PTR(-ESTALE);
 
-        inode = nilfs_iget(sb, ino);
+        root = nilfs_lookup_root(NILFS_SB(sb)->s_nilfs,
+                                 NILFS_CPTREE_CURRENT_CNO);
+        if (!root)
+                return ERR_PTR(-ESTALE);
+
+        /* new file handle type is required to export snapshots */
+        inode = nilfs_iget(sb, root, ino);
+        nilfs_put_root(root);
         if (IS_ERR(inode))
                 return ERR_CAST(inode);
         if (generation && inode->i_generation != generation) {
@@ -815,9 +832,10 @@ 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 inode *root;
         __u64 cno;
-        int err;
+        int err, curr_mnt;
 
         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
         if (!sbi)
@@ -859,6 +877,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
                 goto failed_sbi;
 
         cno = nilfs_last_cno(nilfs);
+        curr_mnt = true;
 
         if (sb->s_flags & MS_RDONLY) {
                 if (nilfs_test_opt(sbi, SNAPSHOT)) {
@@ -881,10 +900,11 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
                                 goto failed_sbi;
                         }
                         cno = sbi->s_snapshot_cno;
+                        curr_mnt = false;
                 }
         }
 
-        err = nilfs_attach_checkpoint(sbi, cno);
+        err = nilfs_attach_checkpoint(sbi, cno, curr_mnt, &fsroot);
         if (err) {
                 printk(KERN_ERR "NILFS: error loading a checkpoint"
                        " (checkpoint number=%llu).\n", (unsigned long long)cno);
@@ -897,7 +917,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
                         goto failed_checkpoint;
         }
 
-        root = nilfs_iget(sb, NILFS_ROOT_INO);
+        root = nilfs_iget(sb, fsroot, NILFS_ROOT_INO);
         if (IS_ERR(root)) {
                 printk(KERN_ERR "NILFS: get root inode failed\n");
                 err = PTR_ERR(root);
@@ -917,6 +937,8 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
                 goto failed_segctor;
         }
 
+        nilfs_put_root(fsroot);
+
         if (!(sb->s_flags & MS_RDONLY)) {
                 down_write(&nilfs->ns_sem);
                 nilfs_setup_super(sbi);
@@ -935,6 +957,7 @@ nilfs_fill_super(struct super_block *sb, void *data, int silent,
 
  failed_checkpoint:
         nilfs_detach_checkpoint(sbi);
+        nilfs_put_root(fsroot);
 
  failed_sbi:
         put_nilfs(nilfs);