ocfs2: return -EROFS to mount.ocfs2 if inode block is invalid

BugLink: https://bugs.launchpad.net/bugs/1775771

[ Upstream commit 025bcbde ]

If metadata is corrupted such as 'invalid inode block', we will get
failed by calling 'mount()' and then set filesystem readonly as below:

  ocfs2_mount
    ocfs2_initialize_super
      ocfs2_init_global_system_inodes
        ocfs2_iget
          ocfs2_read_locked_inode
            ocfs2_validate_inode_block
	      ocfs2_error
	        ocfs2_handle_error
	          ocfs2_set_ro_flag(osb, 0);  // set readonly

In this situation we need return -EROFS to 'mount.ocfs2', so that user
can fix it by fsck.  And then mount again.  In addition, 'mount.ocfs2'
should be updated correspondingly as it only return 1 for all errno.
And I will post a patch for 'mount.ocfs2' too.

Link: http://lkml.kernel.org/r/5A4302FA.2010606@huawei.comSigned-off-by: Jun Piao <piaojun@huawei.com>
Reviewed-by: Alex Chen <alex.chen@huawei.com>
Reviewed-by: Joseph Qi <jiangqi903@gmail.com>
Reviewed-by: Changwei Ge <ge.changwei@h3c.com>
Reviewed-by: Gang He <ghe@suse.com>
Cc: Mark Fasheh <mfasheh@versity.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Junxiao Bi <junxiao.bi@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

fs/ocfs2/super.c

@@ -477,9 +477,8 @@ static int ocfs2_init_global_system_inodes(struct ocfs2_super *osb)
 		new = ocfs2_get_system_file_inode(osb, i, osb->slot_num);
 		if (!new) {
 			ocfs2_release_system_inodes(osb);
-			status = -EINVAL;
+			status = ocfs2_is_soft_readonly(osb) ? -EROFS : -EINVAL;
 			mlog_errno(status);
-			/* FIXME: Should ERROR_RO_FS */
 			mlog(ML_ERROR, "Unable to load system inode %d, "
 			     "possibly corrupt fs?", i);
 			goto bail;
@@ -508,7 +507,7 @@ static int ocfs2_init_local_system_inodes(struct ocfs2_super *osb)
 		new = ocfs2_get_system_file_inode(osb, i, osb->slot_num);
 		if (!new) {
 			ocfs2_release_system_inodes(osb);
-			status = -EINVAL;
+			status = ocfs2_is_soft_readonly(osb) ? -EROFS : -EINVAL;
 			mlog(ML_ERROR, "status=%d, sysfile=%d, slot=%d\n",
 			     status, i, osb->slot_num);
 			goto bail;