GNU bug report logs - #19238
Fully fix du circular warning on bind mounts

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Boris Ranto <borix60 <at> gmail.com>
To: bug-coreutils <at> gnu.org
Subject: Fully fix du circular warning on bind mounts
Date: Mon, 01 Dec 2014 09:54:38 +0100

[Message part 1 (text/plain, inline)]

The du circular warning can still be hit even though a file system is in
good condition. All we need to do is to get the message is to begin
traversing the file system between the bind mount source and bind mount
target directories, i.e this short script reproduces the problem:

# mkdir -p a/b/c
# mount -o bind a a/b/c
# du a/b

The problem is that in this case, the first directory that is detected
by fts as a duplicate directory is directory a/b/c/b which is not a
mount point.

The solution is to traverse the structure all the way to a/b (excluding
a/b) which is detected as the base of the cycle and look up all these
directories in the mount table.

I'm attaching the patch that fixed this problem for me.

-Boris

[0001-du-handle-sub-bind-mount-cycles-gracefully.patch (text/x-patch, attachment)]

Message #10 received at 19238-done <at> debbugs.gnu.org (full text, mbox):

From: Pádraig Brady <P <at> draigBrady.com>
To: Boris Ranto <borix60 <at> gmail.com>, 19238-done <at> debbugs.gnu.org
Subject: Re: bug#19238: Fully fix du circular warning on bind mounts
Date: Mon, 01 Dec 2014 12:49:59 +0000

On 01/12/14 08:54, Boris Ranto wrote:
> The du circular warning can still be hit even though a file system is in
> good condition. All we need to do is to get the message is to begin
> traversing the file system between the bind mount source and bind mount
> target directories, i.e this short script reproduces the problem:
> 
> # mkdir -p a/b/c
> # mount -o bind a a/b/c
> # du a/b
> 
> The problem is that in this case, the first directory that is detected
> by fts as a duplicate directory is directory a/b/c/b which is not a
> mount point.
> 
> The solution is to traverse the structure all the way to a/b (excluding
> a/b) which is detected as the base of the cycle and look up all these
> directories in the mount table.
> 
> I'm attaching the patch that fixed this problem for me.

Very nice. Thanks for the test!
I'll add a NEWS entry and push later.

thanks!
Pádraig

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