On Sun, 19 Aug 2012, Alexandre Oliva wrote:
> On Aug 18, 2012, Alexandre Oliva <oliva@xxxxxxxxxxxxxxxxx> wrote:
>
> > I've looked further into this tonight, and I found out what modifies
> > the timestamps in the inode is (re)issuing caps to a client.
>
> > So, how can we stop pre_cow_old_inode from messing with the old_inode?
> > Any suggestions?
>
> This patch seems to avoid the problem, but is it correct, or is it just
> papering over a problem elsewhere?
I think the real bug is that CInode::first is less than one of the
old_inodes keys. Looking at cow_old_inode(), it looks like first should
always be strictly > than all old_inodes keys. We should probably assert
as much wherever it is convenient to do so...
In any case, can you see where/how that is happening? If this is a dir
inode that has been commited and then refetched from the parent dir, that
probably explains it. For non-multiversion inodes, dn->first ==
in->first, but not so for these guys, and at first glance I'm not seeing
it in the CDir::_fetched() code.
sage
>
> Subject: mds: Don't modify already-created old_inode
>
> In cow_old_inode, do not modify an old_inode that was created before.
>
> Signed-off-by: Alexandre Oliva <oliva@xxxxxxxxxxxxxxxxx>
> ---
> src/mds/CInode.cc | 14 +++++++++-----
> 1 files changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/src/mds/CInode.cc b/src/mds/CInode.cc
> index 53f9e69..fdff86c 100644
> --- a/src/mds/CInode.cc
> +++ b/src/mds/CInode.cc
> @@ -2030,12 +2030,16 @@ old_inode_t& CInode::cow_old_inode(snapid_t follows, bool cow_head)
> inode_t *pi = cow_head ? get_projected_inode() : get_previous_projected_inode();
> map<string,bufferptr> *px = cow_head ? get_projected_xattrs() : get_previous_projected_xattrs();
>
> + bool found = old_inodes.find(follows) != old_inodes.end();
> old_inode_t &old = old_inodes[follows];
> - old.first = first;
> - old.inode = *pi;
> - old.xattrs = *px;
> -
> - dout(10) << " " << px->size() << " xattrs cowed, " << *px << dendl;
> +
> + if (!found) {
> + old.first = first;
> + old.inode = *pi;
> + old.xattrs = *px;
> +
> + dout(10) << " " << px->size() << " xattrs cowed, " << *px << dendl;
> + }
>
> old.inode.trim_client_ranges(follows);
>
> --
> 1.7.7.6
>
>
>
> --
> Alexandre Oliva, freedom fighter http://FSFLA.org/~lxoliva/
> You must be the change you wish to see in the world. -- Gandhi
> Be Free! -- http://FSFLA.org/ FSF Latin America board member
> Free Software Evangelist Red Hat Brazil Compiler Engineer
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