From: "Yan, Zheng " <yanzheng@21cn.com>
To: linux-btrfs@vger.kernel.org
Subject: Re: Disk space accounting and subvolume delete
Date: Tue, 11 May 2010 08:10:38 +0800 [thread overview]
Message-ID: <AANLkTilDHeJ_aRQSKWUTJgIBhlpLHyNRTy4x4ai_MGJI@mail.gmail.com> (raw)
In-Reply-To: <20100510182352.GA21154@untroubled.org>
On Tue, May 11, 2010 at 2:23 AM, Bruce Guenter <bruce@untroubled.org> w=
rote:
> Hi.
>
> When deleting a snapshot, I have observed that the disk space used by
> that snapshot is not immediately released (according to statvfs or df=
).
> Neither "sync" nor "btrfs filesystem sync" releases the disk space
> neither. =A0The only way I have found to actually fully release the d=
isk
> space is to issue the sync and then sleep until the statvfs free numb=
ers
> stop changing.
>
> This is a rather problematic approach to managing disk space. =A0Is t=
here
> any way to either force a wait until the disk space has been released=
?
>
> My application is automatically managing disk space in the presence o=
f
> snapshots. =A0I allow the disk (a backup) to fill up with snapshots u=
ntil
> it is nearly full, and then to delete snapshots until I have a thresh=
old
> free. =A0However, without the disk space being released promptly and =
no
> way to wait until it is released, the loop can't tell how many snapsh=
ots
> to delete.
>
This is because the snapshot deleting ioctl only removes the a link.
The corresponding tree is dropped in the background by a kernel thread.
We could probably add another ioctl that waits until the tree has been
completely dropped.
Yan, Zheng
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" =
in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2010-05-11 0:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-10 18:23 Disk space accounting and subvolume delete Bruce Guenter
2010-05-10 18:50 ` Josef Bacik
2010-05-11 0:10 ` Yan, Zheng [this message]
2010-05-11 15:45 ` Bruce Guenter
2010-05-12 5:02 ` Yan, Zheng
2010-05-12 21:56 ` Mike Fleetwood
2010-05-31 19:01 ` Bruce Guenter
2010-05-31 20:34 ` Mike Fedyk
2010-06-01 2:32 ` Yan, Zheng
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=AANLkTilDHeJ_aRQSKWUTJgIBhlpLHyNRTy4x4ai_MGJI@mail.gmail.com \
--to=yanzheng@21cn.com \
--cc=linux-btrfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).