From: Dean Hildebrand <seattleplus@gmail.com>
To: Fred Isaman <iisaman@netapp.com>
Cc: linux-nfs@vger.kernel.org
Subject: Re: [PATCH 00/22] LAYOUTGET invocation
Date: Tue, 25 May 2010 11:27:18 -0700 [thread overview]
Message-ID: <4BFC1686.4000509@gmail.com> (raw)
In-Reply-To: <1273972993-15369-1-git-send-email-iisaman@netapp.com>
Fred Isaman wrote:
> (My apologies for the 4 patches that went out about 1/2 hour ago. Please ignore those.)
>
> This patch series limits LAYOUTGET invocation to the beginning of the IO paths.
>
> It is intended for the pnfs_submit branch, without reversion in a post_submit branch.
>
> Patches 1-4 revert direct IO. Commit is already broken, and this series breaks them further. The problem is that the direct IO redefines data->wb_req and data->pages, so that it can only work with the pnfs code if we don't look at those fields.
>
Can you give some history on this? Is it crashing? Has this problem
been around for a long time or is a new set of patches causing the
problem? Does this affect pNFS O_DIRECT or all O_DIRECT code?
I don't think revert is the right way to go about this. Removing
support for O_DIRECT because changes to the non-O_DIRECT path break it
would not fly in the mainline, and so I don't see why it would fly
here. At the minimum, since O_DIRECT is a B-list feature, I could see
it being commented/ifdef'd out for the time being, but completely
removing the patches is extremely invasive considering this is a b-list
development branch.
Dean
> Patches 5-8 do some code cleanup in preperation for the real work.
>
> Patches 9-19 implement the change. NOTE that patch 19 changes the calling convention of the layout drivers commit calls. There is no longer a universal lseg for the commit, instead each nfs_page has an lseg attached, with NULL meaning to go through the MDS.
>
> Patches 20-22 rework the filelayout commit function, and then do some code cleanup this enables.
>
>
>
> The basic idea of these patches is as follows:
>
> We attempt to grab a lseg (possibly invoking LAYOUTGET) early in the IO. If we succeed, we refcount and stash it, using it through the rest of the io. If we fail, we revert to straight nfs, even if the area becomes covered by a layout due to other io.
>
> The tricky, though hopefully anomalous, case is when we start without the layout, but have it at this particular stage of the IO. We ignore this for the moment at write_pages, which will cause block and object to issue CB_LAYOUTRECALL. At commit, it is tricky to handle, but since block doesn't use commit, and file needs to handle complicated splitting anyway, I just push all complicated decisions of splitting commit between nfs (for IO started without layout) and pnfs to the driver.
>
> Fred
>
> --
> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at http://vger.kernel.org/majordomo-info.html
>
next prev parent reply other threads:[~2010-05-25 18:26 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-16 1:22 [PATCH 00/22] LAYOUTGET invocation Fred Isaman
2010-05-16 1:22 ` [PATCH 01/22] Revert "pnfs-nonfilelayout: Prelim support for non-file layout O_DIRECT" Fred Isaman
2010-05-16 1:22 ` [PATCH 02/22] Revert "pnfs: Enable O_DIRECT write path." Fred Isaman
2010-05-16 1:22 ` [PATCH 03/22] Revert "pnfs: Enable O_DIRECT read path." Fred Isaman
2010-05-16 1:22 ` [PATCH 04/22] Revert "pnfs: Add function to set up O_DIRECT I/O" Fred Isaman
2010-05-16 1:22 ` [PATCH 05/22] pnfs: filelayout: clean and breakup nfs4_pnfs_dserver_get Fred Isaman
2010-05-16 1:22 ` [PATCH 06/22] pnfs: filelayout: remove some dead code from filelayout_commit Fred Isaman
2010-05-16 1:22 ` [PATCH 07/22] pnfs: remove PNFS_LAYOUTGET_ON_OPEN Fred Isaman
2010-05-16 1:22 ` [PATCH 08/22] pnfs: track the number of outstanding commits Fred Isaman
2010-05-16 1:23 ` [PATCH 09/22] pnfs_submit: mandate basic io path operations for layout drivers Fred Isaman
2010-05-16 1:23 ` [PATCH 10/22] pnfs_submit: expose pnfs_update_layout, put_lseg, and get_lseg functions Fred Isaman
2010-05-16 1:23 ` [PATCH 11/22] pnfs_submit: stash and refcount lseg in read path Fred Isaman
2010-05-16 1:23 ` [PATCH 12/22] pnfs_submit: read path changeover Fred Isaman
2010-05-16 1:23 ` [PATCH 13/22] pnfs_submit: use fsdata to pass lseg Fred Isaman
2010-05-16 1:23 ` [PATCH 14/22] pnfs_submit: stash and refcount lseg in write path Fred Isaman
2010-05-16 1:23 ` [PATCH 15/22] pnfs_submit: remove pnfs_file_operations Fred Isaman
2010-05-16 1:23 ` [PATCH 16/22] pnfs_submit: remove pnfs_update_layout_commit Fred Isaman
2010-05-16 1:23 ` [PATCH 17/22] pnfs_submit: remove pnfs_writepages LAYOUTGET invocation Fred Isaman
2010-05-16 1:23 ` [PATCH 18/22] pnfs: export some commit error handling for use by layout drivers Fred Isaman
2010-05-16 1:23 ` [PATCH 19/22] pnfs_submit: API change: remove pnfs_commit layoutget invocation Fred Isaman
2010-05-16 1:23 ` [PATCH 20/22] pnfs_submit: filelayout: rewrite filelayout_commit to use new API Fred Isaman
2010-05-16 1:23 ` [PATCH 21/22] pnfs_submit: remove unecessary pnfs_fl_call_data field pnfs_client Fred Isaman
2010-05-16 1:23 ` [PATCH 22/22] pnfs_submit: remove unecessary pnfs_fl_call_data field commit_through_mds Fred Isaman
2010-05-25 18:27 ` Dean Hildebrand [this message]
2010-05-25 19:03 ` [PATCH 00/22] LAYOUTGET invocation Fred Isaman
2010-05-25 20:14 ` Dean Hildebrand
2010-05-26 8:43 ` Boaz Harrosh
2010-05-26 17:39 ` Dean Hildebrand
2010-05-26 17:58 ` Fred Isaman
2010-05-26 18:13 ` Boaz Harrosh
2010-05-26 18:53 ` Dean Hildebrand
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=4BFC1686.4000509@gmail.com \
--to=seattleplus@gmail.com \
--cc=iisaman@netapp.com \
--cc=linux-nfs@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).