linux-ext4 - Re: Why does not freeblocks number change after deleting a big file?

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 6 May 2014 13:57:48 +0400
From:	Azat Khuzhin <a3at.mail@...il.com>
To:	Younger Liu <younger.liucn@...il.com>
Cc:	linux-ext4@...r.kernel.org
Subject: Re: Why does not freeblocks number change after deleting a big file?

On Tue, May 06, 2014 at 11:32:12AM +0800, Younger Liu wrote:
> Hi:
>   Analyze ext4 filesystem with "debugfs -R "stats" <device>",
> Why does not free blocks number change after deleting a big file?
> 
> The big file:
> # stat test
>   file："test"
>   size：290554084       blocks：567496     IO block：4096
> 
> before deleting the file "test":
> # debugfs -R "stats" /dev/sdb
> ...
> Inode count:              243593216
> Block count:              1948728320
> Reserved block count:     97436416
> Free blocks:              406830314
> Free inodes:              151667854
> ...
> 
> deleting the file "test"
> # debugfs -R "stats" /dev/sdb
> ...
> Inode count:              243593216
> Block count:              1948728320
> Reserved block count:     97436416
> Free blocks:              406830314
> Free inodes:              151667854

Hi,

Seems that you are trying to do this on a mounted partition, and the
super block are not dumped to disk after every write/flush.

You could use statfs(2) instead of debugfs/stats command, or "mount -o
remount /dev/sdb_X_" and after debugfs, this _must_ work only in case
you don't have journal.

For more information you could look into ext4_commit_super().

> ...
> 
>      Younger
>      thx.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
> the body of a message to majordomo@...r.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

-- 
Respectfully
Azat Khuzhin
--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html