On Thu, Sep 28, 2017 at 5:16 AM Micha Krause <mi...@krausam.de> wrote:
> Hi,
>
> I had a chance to catch John Spray at the Ceph Day, and he suggested that
> I try to reproduce this bug in luminos.
>
> To fix my immediate problem we discussed 2 ideas:
>
> 1. Manually edit the Meta-data, unfortunately I was not able to find any
> Information on how the meta-data is structured :-(
>
> 2. Edit the code to set the link count to 0 if it is negative:
>
>
> diff --git a/src/mds/StrayManager.cc b/src/mds/StrayManager.cc
> index 9e53907..2ca1449 100644
> --- a/src/mds/StrayManager.cc
> +++ b/src/mds/StrayManager.cc
> @@ -553,6 +553,10 @@ bool StrayManager::__eval_stray(CDentry *dn, bool
> delay)
> logger->set(l_mdc_num_strays_delayed, num_strays_delayed);
> }
>
> + if (in->inode.nlink < 0) {
> + in->inode.nlink=0;
> + }
> +
> // purge?
> if (in->inode.nlink == 0) {
> // past snaprealm parents imply snapped dentry remote links.
> diff --git a/src/xxHash b/src/xxHash
> --- a/src/xxHash
> +++ b/src/xxHash
> @@ -1 +1 @@
>
>
> Im not sure if this works, the patched mds no longer crashes, however I
> expected that this value:
>
> root@mds02:~ # ceph daemonperf mds.1
> -----mds------ --mds_server-- ---objecter--- -----mds_cache-----
> ---mds_log----
> rlat inos caps|hsr hcs hcr |writ read actv|recd recy stry purg|segs evts
> subm|
> 0 100k 0 | 0 0 0 | 0 0 0 | 0 0 625k 0 | 30
> 25k 0
> ^^^^
>
> Should go down, but it stays at 625k, unfortunately I don't have another
> System to compare.
>
> After I started the patched mds once, I reverted back to an unpatched mds,
> and it also stopped crashing, so I guess it did "fix" something.
>
>
> A question just out of curiosity, I tried to log these events with
> something like:
>
> dout(10) << "Fixed negative inode count";
>
> or
>
> derr << "Fixed negative inode count";
>
> But my compiler yelled at me for trying this.
>
dout and derr are big macros. You need to end the line with " << dendl;" to
close it off.
>
> Micha Krause
> _______________________________________________
> ceph-users mailing list
> ceph-users@lists.ceph.com
> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
>
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