nilfs2: return EBUSY against delete request on snapshot

This helps userland programs like the rmcp command to distinguish
error codes returned against a checkpoint removal request.

Previously -EPERM was returned, and not discriminable from real
permission errors.  This also allows removal of the latest checkpoint
because the deletion leads to create a new checkpoint, and thus it's
harmless for the filesystem.

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

diff --git a/fs/nilfs2/cpfile.c b/fs/nilfs2/cpfile.c
index b5a8cd6..4184c1c 100644 (file)
--- a/fs/nilfs2/cpfile.c
+++ b/fs/nilfs2/cpfile.c
@@ -295,10 +295,6 @@ int nilfs_cpfile_delete_checkpoints(struct inode *cpfile,
                return -EINVAL;
        }
 
-       /* cannot delete the latest checkpoint */
-       if (start == nilfs_mdt_cno(cpfile) - 1)
-               return -EPERM;
-
        down_write(&NILFS_MDT(cpfile)->mi_sem);
 
        ret = nilfs_cpfile_get_header_block(cpfile, &header_bh);
@@ -542,20 +538,14 @@ int nilfs_cpfile_delete_checkpoint(struct inode *cpfile, __u64 cno)
        struct nilfs_cpinfo ci;
        __u64 tcno = cno;
        ssize_t nci;
-       int ret;
 
        nci = nilfs_cpfile_do_get_cpinfo(cpfile, &tcno, &ci, sizeof(ci), 1);
        if (nci < 0)
                return nci;
        else if (nci == 0 || ci.ci_cno != cno)
                return -ENOENT;
-
-       /* cannot delete the latest checkpoint nor snapshots */
-       ret = nilfs_cpinfo_snapshot(&ci);
-       if (ret < 0)
-               return ret;
-       else if (ret > 0 || cno == nilfs_mdt_cno(cpfile) - 1)
-               return -EPERM;
+       else if (nilfs_cpinfo_snapshot(&ci))
+               return -EBUSY;
 
        return nilfs_cpfile_delete_checkpoints(cpfile, cno, cno + 1);
 }