nilfs2: deny write access to inodes in snapshots

Snapshots of nilfs are read-only.

After super block instances (sb) will be unified, nilfs will need to
check write access by a way other than implicit test with
IS_RDONLY(inode).  This is because IS_RDONLY() refers to MS_RDONLY bit
of inode->i_sb->s_flags and it will become inaccurate after the
unification of sb.

To prepare for the issue, this uses i_op->permission to deny write
access to inodes in snapshots.

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

1 files changed, 1 insertions, 3 deletions

diff --git a/fs/nilfs2/nilfs.h b/fs/nilfs2/nilfs.h
index 3870c109aba3..cf5507a2a178 100644
--- a/fs/nilfs2/nilfs.h
+++ b/fs/nilfs2/nilfs.h
@@ -201,12 +201,9 @@ static inline struct inode *nilfs_dat_inode(const struct the_nilfs *nilfs)
  */
 #ifdef CONFIG_NILFS_POSIX_ACL
 #error "NILFS: not yet supported POSIX ACL"
-extern int nilfs_permission(struct inode *, int, struct nameidata *);
 extern int nilfs_acl_chmod(struct inode *);
 extern int nilfs_init_acl(struct inode *, struct inode *);
 #else
-#define nilfs_permission   NULL
-
 static inline int nilfs_acl_chmod(struct inode *inode)
 {
         return 0;
@@ -256,6 +253,7 @@ extern void nilfs_update_inode(struct inode *, struct buffer_head *);
 extern void nilfs_truncate(struct inode *);
 extern void nilfs_evict_inode(struct inode *);
 extern int nilfs_setattr(struct dentry *, struct iattr *);
+int nilfs_permission(struct inode *inode, int mask);
 extern int nilfs_load_inode_block(struct nilfs_sb_info *, struct inode *,
                                   struct buffer_head **);
 extern int nilfs_inode_dirty(struct inode *);