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From: Amir Goldstein <amir73il@gmail.com>
To: Miklos Szeredi <miklos@szeredi.hu>
Cc: Jeff Layton <jlayton@poochiereds.net>,
	"J . Bruce Fields" <bfields@fieldses.org>,
	overlayfs <linux-unionfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v2 01/17] ovl: document NFS export
Date: Fri, 12 Jan 2018 20:50:18 +0200	[thread overview]
Message-ID: <CAOQ4uxizCq5gmDdDWeQS0CE1j2GhN9R=BNSsoL4b2-50gUg0Pg@mail.gmail.com> (raw)
In-Reply-To: <CAJfpegs1FLcH8O+1ay+G6wK+VNX7UpOF+QwdC3eCDWDFr+CowQ@mail.gmail.com>

On Fri, Jan 12, 2018 at 5:49 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Fri, Jan 12, 2018 at 4:43 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>> On Thu, Jan 11, 2018 at 5:26 PM, Amir Goldstein <amir73il@gmail.com> wrote:
>
>>> When decoding an upper dir, the decoded upper path is the same path as
>>> the overlay path, so we lookup same path in overlay.
>>>
>>> When decoding a lower dir from layer 1, every ancestor is either still lower
>>> (and therefore not renamed) or been copied up and indexed by lower inode,
>>> so we can use index to know the path of every ancestor in overlay (or if it
>>> has been removed).
>>>
>>> When decoding a lower dir from layer 2, there may be an ancestor in layer 2
>>> covered by whiteout in layer 1 and redirected from another directory in layer 1.
>>> In that case, we have no information in index to reconstruct the overlay path
>>> from the connected layer 2 directory, hence, we cannot decode a connected
>>> overlay directory from dir file handle encoded from layer 2.
>>
>> Now I understand: we are missing the back pointer from layer2 to
>> layer1 that the index provides us when going from lower to upper.
>>
>> However, this is only needed if we end up below a redirecting layer.
>> So we could limit copy-up to these cases.  It doesn't seem hard to
>> keep track of highest layer that had a redirect in each overlay
>> dentry, and when ending up on a layer below that, mark the overlay
>> dentry COPY_UP_FOR_ENCODE.  This information is constant, since lower
>> layers are immutable, so no worries there.

Right.

>> Can postpone this to a
>> later version, but the takeaway is that we need to mark the fh to
>> indicate if it's a merge upper or not.
>

This I did not get.
The fh is marked upper or not.
If it is upper, we get the real upper path and lookup that path in overlay.
Whether upper is merge or not, overlay lookup will find out.

What am I missing?


> And BTW, we need to copy up only the directory that has the redirect,
> since that's where we are missing the mapping in the lower layers.
> Below that in the tree, we are fine, until we come across another
> redirect, and so on...
>

So actually, I can use OVL_RENAMED flag from patch 8/23
and implement ovl_copy_up_renamed_parent() on encode
This will actually also cover the case of dir in layer1 that has a
non-indexed redirected upper parent.

Thanks,
Amir.

  reply	other threads:[~2018-01-12 18:50 UTC|newest]

Thread overview: 68+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-04 17:20 [PATCH v2 00/17] Overlayfs NFS export support Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 01/17] ovl: document NFS export Amir Goldstein
2018-01-11 16:06   ` Miklos Szeredi
2018-01-11 16:26     ` Amir Goldstein
2018-01-12 15:43       ` Miklos Szeredi
2018-01-12 15:49         ` Miklos Szeredi
2018-01-12 18:50           ` Amir Goldstein [this message]
2018-01-13  8:54           ` Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 02/17] ovl: encode pure upper file handles Amir Goldstein
2018-01-18 10:31   ` Miklos Szeredi
2018-01-04 17:20 ` [PATCH v2 03/17] ovl: decode " Amir Goldstein
2018-01-18 14:09   ` Miklos Szeredi
2018-01-18 14:34     ` Amir Goldstein
2018-01-18 14:39       ` Miklos Szeredi
2018-01-18 19:49         ` Amir Goldstein
2018-01-18 20:10           ` Miklos Szeredi
2018-01-18 20:35             ` Amir Goldstein
2018-01-18 22:57               ` Amir Goldstein
2018-01-19  0:23                 ` Amir Goldstein
2018-01-19 10:39                   ` Miklos Szeredi
2018-01-19 11:07                     ` Amir Goldstein
2018-01-19 20:10                       ` Amir Goldstein
2018-01-24 10:34                         ` Miklos Szeredi
2018-01-24 11:04                           ` Amir Goldstein
2018-01-24 11:18                             ` Amir Goldstein
2018-01-24 11:55                               ` Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 04/17] ovl: decode connected upper dir " Amir Goldstein
2018-01-05 12:33   ` Amir Goldstein
2018-01-05 15:18     ` J . Bruce Fields
2018-01-05 15:34       ` Amir Goldstein
2018-01-15 11:41     ` Miklos Szeredi
2018-01-15 11:33   ` Miklos Szeredi
2018-01-15 12:20     ` Amir Goldstein
2018-01-15 14:56       ` Miklos Szeredi
2018-01-17 11:18         ` Amir Goldstein
2018-01-17 12:20           ` Amir Goldstein
2018-01-17 13:29             ` Amir Goldstein
2018-01-17 15:42           ` Miklos Szeredi
2018-01-17 16:34             ` Amir Goldstein
2018-01-17 21:36               ` Amir Goldstein
2018-01-18  8:22               ` Miklos Szeredi
2018-01-18  8:47                 ` Amir Goldstein
2018-01-18  9:12                   ` Miklos Szeredi
2018-01-18 10:28                     ` Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 05/17] ovl: encode non-indexed upper " Amir Goldstein
2018-01-15 11:58   ` Miklos Szeredi
2018-01-15 12:07     ` Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 06/17] ovl: copy up before encoding dir file handle when ofs->numlower > 1 Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 07/17] ovl: encode lower file handles Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 08/17] ovl: decode lower non-dir " Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 09/17] ovl: decode indexed " Amir Goldstein
2018-01-18 13:11   ` Miklos Szeredi
2018-01-04 17:20 ` [PATCH v2 10/17] ovl: decode lower file handles of unlinked but open files Amir Goldstein
2018-01-16  9:16   ` Miklos Szeredi
2018-01-16  9:37     ` Amir Goldstein
2018-01-16 10:10       ` Miklos Szeredi
2018-01-16 10:40         ` Amir Goldstein
2018-01-16 11:07           ` Miklos Szeredi
2018-01-17 21:05         ` Amir Goldstein
2018-01-18 14:18   ` Amir Goldstein
2018-02-27 11:35     ` Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 11/17] ovl: decode indexed dir file handles Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 12/17] ovl: decode pure lower " Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 13/17] ovl: hash directory inodes for NFS export Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 14/17] ovl: lookup connected ancestor of dir in inode cache Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 15/17] ovl: lookup indexed ancestor of lower dir Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 16/17] ovl: wire up NFS export support Amir Goldstein
2018-01-04 17:20 ` [PATCH v2 17/17] nfsd: encode stat->mtime for getattr instead of inode->i_mtime Amir Goldstein

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