Re: RFE: per-subvolume timestamp that is updated on every change to a subvolume

[Qu Wenruo <quwenruo@cn.fujitsu.com>]

-------- Original Message --------
Subject: RFE: per-subvolume timestamp that is updated on every change to 
a subvolume
From: Lennart Poettering <lennart@poettering.net>
To: <linux-btrfs@vger.kernel.org>
Date: 2015年01月06日 01:27
> Heya!
>
> I am looking for a nice way to query the overall last modification
> timestamp of a subvolume. i.e. the most recent mtime of *any* file or
> directory within a subvolume. Ideally, I think, there was a
> btrfs_timespec field for this in "struct btrfs_root_item", alas there
> isn't afaics. Any chance this can be added?
In fact, btrfs_root_item contains one btrfs_inode_item, which contains 
the a/c/m/otime.
But not sure if it contains the time you need.

I'd better add acmotime output for inode_item in btrfs-debug-tree and 
try myself.

Thanks,
Qu
>
> Or is there another workable way to query this value? Maybe determine
> it from the current generation of a subvolume or so? Is that tracked?
> Ideas?
>
> Lennart
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