nilfs2: use checkpoint tree for mount check of snapshots

This rewrites nilfs_checkpoint_is_mounted() function so that it
decides whether a checkpoint is mounted by whether the corresponding
root object is found in checkpoint tree.

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

diff --git a/fs/nilfs2/the_nilfs.c b/fs/nilfs2/the_nilfs.c
index f1d599273d9e310874c0c75920a925a90c44d560..89c78562d0e995bf6f6f04c44e134810a5ab7cf9 100644 (file)
--- a/fs/nilfs2/the_nilfs.c
+++ b/fs/nilfs2/the_nilfs.c
@@ -954,26 +954,20 @@ struct nilfs_sb_info *nilfs_find_sbinfo(struct the_nilfs *nilfs,
 int nilfs_checkpoint_is_mounted(struct the_nilfs *nilfs, __u64 cno,
                                int snapshot_mount)
 {
-       struct nilfs_sb_info *sbi;
-       int ret = 0;
+       struct nilfs_root *root;
+       int ret;
 
-       down_read(&nilfs->ns_super_sem);
-       if (cno == 0 || cno > nilfs->ns_cno)
-               goto out_unlock;
+       if (cno < 0 || cno > nilfs->ns_cno)
+               return false;
 
-       list_for_each_entry(sbi, &nilfs->ns_supers, s_list) {
-               if (sbi->s_snapshot_cno == cno &&
-                   (!snapshot_mount || nilfs_test_opt(sbi, SNAPSHOT))) {
-                                       /* exclude read-only mounts */
-                       ret++;
-                       break;
-               }
-       }
-       /* for protecting recent checkpoints */
        if (cno >= nilfs_last_cno(nilfs))
-               ret++;
+               return true;    /* protect recent checkpoints */
 
- out_unlock:
-       up_read(&nilfs->ns_super_sem);
+       ret = false;
+       root = nilfs_lookup_root(nilfs, cno);
+       if (root) {
+               ret = true;
+               nilfs_put_root(root);
+       }
        return ret;
 }