From: Eric Sandeen <sandeen@sandeen.net>
To: Halsey Pian <halsey.pian@gmail.com>, linux-xfs@vger.kernel.org
Subject: Re: With respect to XFS Bitmap flush to disk
Date: Mon, 27 Feb 2017 09:33:10 -0600 [thread overview]
Message-ID: <5b2d2e73-bd7e-e705-bd56-d764b7801492@sandeen.net> (raw)
In-Reply-To: <004e01d2909e$d9ce1580$8d6a4080$@gmail.com>
On 2/26/17 8:11 PM, Halsey Pian wrote:
> Dear All,
>
> Recently, I try to read analyze the bitmap of XFS file system, it
> seems that I cannot read the latest bitmap from hard disk involving
> the XFS, and cannot read the accurate info even after a long time.
> For example, i cannot get the relevant bitmap info after I add/delete
> a big file to/from XFS file system.
In general, attempting to read metadata from a mounted block device
isn't going to be reliable. For one, changes may only be staged
in the log, and not yet in their final disk location.
> I tried several solution, and find it out that I must execute
> xfs_freeze for the XFS partition in CentOS7, and it seems that
> xfs_freeze doesn’t work for XFS version included in Redhat6.5, I must
> umount/mount the xfs, then I can get the latest bitmap info related
> to the latest data located in disk.
>
> What strategy does XFS use to cache/flush bitmap to hard disk? How
> can I get the accurate bitmap info especially for Redhat6 series
> Operating System? Could you please give help on it?
The short answer is "you can't." Directly reading the block device
while mounted isn't a supported use of the filesystem.
What are you trying to do, here?
Thanks,
-Eric
> Thanks in advance! ☺
>
>
>
>
> Halsey Pian
>
>
> -- To unsubscribe from this list: send the line "unsubscribe
> linux-xfs" in the body of a message to majordomo@vger.kernel.org More
> majordomo info at http://vger.kernel.org/majordomo-info.html
>
prev parent reply other threads:[~2017-02-27 15:41 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-27 2:11 With respect to XFS Bitmap flush to disk Halsey Pian
2017-02-27 11:23 ` Stefan Ring
2017-02-27 15:33 ` Eric Sandeen [this message]
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=5b2d2e73-bd7e-e705-bd56-d764b7801492@sandeen.net \
--to=sandeen@sandeen.net \
--cc=halsey.pian@gmail.com \
--cc=linux-xfs@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