Re: [PATCH] Btrfs-progs: introduce '-p' option and <fullpath> into subvolume set-default command

On 2012-10-9 22:44, David Sterba wrote:

On Mon, Sep 24, 2012 at 02:42:13PM +0800, Chen Yang wrote:

quoted

In command "btrfs subvolume set-default", we used subvolume <id> and <path>
to set the default subvolume of a filesystem. It's not easy for a common
user,

What is not easy? How often do you set-default subvolume that it's a
concern to do it in two steps (list and set-default)?

This patch is mean to improve the UI
If the description above if improper, I will fix it.

quoted

so I improved it and the <fullpath> of a subvolume can be used to
set the default subvolume of a filesystem.

Setting the default directly from a given path would be a good UI
improvement.

quoted

@@ -601,23 +602,66 @@ static int cmd_subvol_get_default(int argc, char **argv)
 static const char * const cmd_subvol_set_default_usage[] = {
-	"btrfs subvolume set-default <subvolid> <path>",
+	"btrfs subvolume set-default [-p] [<subvolid>] <path>",

This new syntax allows these forms:

	1. set-default /path

The "path" must be a subvolume path

	2. set-default -p /path

The "path" can be any path under a mount point, if path is not a subvolume, 
The parent tree (subvolume) of the path will be find out and set to be default

	3. set-default id /path

current behaviour

	4. set-default -p id /path

Error! The improper description of the usage causes this misuse, I will fix it.

3 is the current behaviour, can you please explain the rest to me? I'm
afraid I'm not following the idea.

I'm sorry to make you confused for giving an unclear usage about the new option of the command. 
I'm writing a new version. I will send it later.

quoted

 	"Set the default subvolume of a filesystem",
+	"-p    Set the parent tree(subvolume) of the PATH",
+	"      as the default subvolume, if PATH is not a subvolume",

"if PATH is not a subvolume" -- so I don't specify the mountpoint for
PATH and I'm supposed to know if the path is or is not a subvolume --
this is another step I need to do (because I want to be sure that I'm
setting the right subvol), this does not save the commands compared to
the current status.

The option “-p” is only used like this “set-default -p /path”, 
if PATH is not a subvolume -p" will help to find the parent tree (subvolume) of the PATH, and set it default.

quoted

 	NULL
 };

thanks,
david

thanks for your advise,
chen yang