[PATCH v2 19/34] ocfs2: keep the current mount options on remount

[Christian Brauner <brauner@kernel.org>]

ocfs2_init_fs_context() doesn't inherit the current mount options for a
reconfigure. But ocfs2_check_set_options() insists on exactly one
heartbeat mode and ocfs2_reconfigure() refuses to change the data mode.
So every remount without heartbeat= fails with EINVAL, including
emergency remount (sysrq u) which passes no options at all, and that
WARNs for every ocfs2 mounted read-write. A remount that does pass
heartbeat= silently resets every option it doesn't repeat, e.g. noacl,
errors=, barrier= and preferred_slot=.

So start a reconfigure from the current options like exfat and gfs2 do.
Asking for a different data or heartbeat mode still fails with EINVAL.

The next patch stops ocfs2 from setting SB_RDONLY after errors. An
errored ocfs2 then stays read-write and emergency remount would run into
this as well.

Signed-off-by: Christian Brauner (Amutable) <brauner@kernel.org>
---
 fs/ocfs2/super.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/fs/ocfs2/super.c b/fs/ocfs2/super.c
index 0af2245ae303..67283244426e 100644
--- a/fs/ocfs2/super.c
+++ b/fs/ocfs2/super.c
@@ -1222,6 +1222,19 @@ static int ocfs2_init_fs_context(struct fs_context *fc)
 	mopt->resv_level = OCFS2_DEFAULT_RESV_LEVEL;
 	mopt->dir_resv_level = -1;
 
+	/*
+	 * Start from the current options so a remount only changes what it
+	 * specifies, emergency remount passes none at all.
+	 */
+	if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
+		struct ocfs2_super *osb = OCFS2_SB(fc->root->d_sb);
+
+		mopt->mount_opt = osb->s_mount_opt;
+		mopt->atime_quantum = osb->s_atime_quantum;
+		mopt->slot = osb->preferred_slot;
+		mopt->user_stack = ocfs2_userspace_stack(osb);
+	}
+
 	fc->fs_private = mopt;
 	fc->ops = &ocfs2_context_ops;
 

-- 
2.53.0


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