From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jeff Layton <jlayton@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Jan Kara <jack@suse.cz>, Matthew Wilcox <mawilcox@microsoft.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Dave Chinner <david@fromorbit.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"J. Bruce Fields" <bfields@fieldses.org>,
Linux MM <linux-mm@kvack.org>, Jeff Moyer <jmoyer@redhat.com>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Ross Zwisler <ross.zwisler@linux.intel.com>,
linux-xfs@vger.kernel.org,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH v3 12/13] dax: handle truncate of dma-busy pages
Date: Fri, 20 Oct 2017 10:27:22 -0700 [thread overview]
Message-ID: <CAPcyv4iGN6KO_ggJ-vTHCPWanudY3Gq6n=+9sbnMsnTeF56uJA@mail.gmail.com> (raw)
In-Reply-To: <20171020163221.GB26320@lst.de>
On Fri, Oct 20, 2017 at 9:32 AM, Christoph Hellwig <hch@lst.de> wrote:
> On Fri, Oct 20, 2017 at 08:42:00AM -0700, Dan Williams wrote:
>> I agree, but it needs quite a bit more thought and restructuring of
>> the truncate path. I also wonder how we reclaim those stranded
>> filesystem blocks, but a first approximation is wait for the
>> administrator to delete them or auto-delete them at the next mount.
>> XFS seems well prepared to reflink-swap these DMA blocks around, but
>> I'm not sure about EXT4.
>
> reflink still is an optional and experimental feature in XFS. That
> being said we should not need to swap block pointers around on disk.
> We just need to prevent the block allocator from reusing the blocks
> for new allocations, and we have code for that, both for transactions
> that haven't been committed to disk yet, and for deleted blocks
> undergoing discard operations.
>
> But as mentioned in my second mail from this morning I'm not even
> sure we need that. For short-term elevated page counts like normal
> get_user_pages users I think we can just wait for the page count
> to reach zero, while for abuses of get_user_pages for long term
> pinning memory (not sure if anyone but rdma is doing that) we'll need
> something like FL_LAYOUT leases to release the mapping.
I'll take a look at hooking this up through a page-idle callback. Can
I get some breadcrumbs to grep for from XFS folks on how to set/clear
the busy state of extents?
next prev parent reply other threads:[~2017-10-20 17:27 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-20 2:38 [PATCH v3 00/13] dax: fix dma vs truncate and remove 'page-less' support Dan Williams
2017-10-20 2:39 ` [PATCH v3 01/13] dax: quiet bdev_dax_supported() Dan Williams
2017-10-20 2:39 ` [PATCH v3 02/13] dax: require 'struct page' for filesystem dax Dan Williams
2017-10-20 7:57 ` Christoph Hellwig
2017-10-20 15:23 ` Dan Williams
2017-10-20 16:29 ` Christoph Hellwig
2017-10-20 22:29 ` Dan Williams
2017-10-21 3:20 ` Matthew Wilcox
2017-10-21 4:16 ` Dan Williams
2017-10-21 8:15 ` Christoph Hellwig
2017-10-23 5:18 ` Martin Schwidefsky
2017-10-23 8:55 ` Dan Williams
2017-10-23 10:44 ` Martin Schwidefsky
2017-10-23 11:20 ` Dan Williams
2017-10-20 2:39 ` [PATCH v3 03/13] dax: stop using VM_MIXEDMAP for dax Dan Williams
2017-10-20 2:39 ` [PATCH v3 04/13] dax: stop using VM_HUGEPAGE " Dan Williams
2017-10-20 2:39 ` [PATCH v3 05/13] dax: stop requiring a live device for dax_flush() Dan Williams
2017-10-20 2:39 ` [PATCH v3 06/13] dax: store pfns in the radix Dan Williams
2017-10-20 2:39 ` [PATCH v3 07/13] dax: warn if dma collides with truncate Dan Williams
2017-10-20 2:39 ` [PATCH v3 08/13] tools/testing/nvdimm: add 'bio_delay' mechanism Dan Williams
2017-10-20 2:39 ` [PATCH v3 09/13] IB/core: disable memory registration of fileystem-dax vmas Dan Williams
2017-10-20 2:39 ` [PATCH v3 10/13] mm: disable get_user_pages_fast() for dax Dan Williams
2017-10-20 2:39 ` [PATCH v3 11/13] fs: use smp_load_acquire in break_{layout,lease} Dan Williams
2017-10-20 12:39 ` Jeffrey Layton
2017-10-20 2:40 ` [PATCH v3 12/13] dax: handle truncate of dma-busy pages Dan Williams
2017-10-20 13:05 ` Jeff Layton
2017-10-20 15:42 ` Dan Williams
2017-10-20 16:32 ` Christoph Hellwig
2017-10-20 17:27 ` Dan Williams [this message]
2017-10-20 20:36 ` Brian Foster
2017-10-21 8:11 ` Christoph Hellwig
2017-10-20 2:40 ` [PATCH v3 13/13] xfs: wire up FL_ALLOCATED support Dan Williams
2017-10-20 7:47 ` [PATCH v3 00/13] dax: fix dma vs truncate and remove 'page-less' support Christoph Hellwig
2017-10-20 9:31 ` Christoph Hellwig
2017-10-26 10:58 ` Jan Kara
2017-10-26 23:51 ` Williams, Dan J
2017-10-27 6:48 ` Dave Chinner
[not found] ` <CAA9_cmdx7T2jnfw6TvL0_3ytfs-h-X06uF3_7Ex-YP12YKpwng@mail.gmail.com>
2017-10-29 21:52 ` Dave Chinner
2017-10-27 6:45 ` Christoph Hellwig
2017-10-29 23:46 ` Dan Williams
2017-10-30 2:00 ` Dave Chinner
2017-10-30 8:38 ` Jan Kara
2017-10-30 11:20 ` Dave Chinner
2017-10-30 17:51 ` Dan Williams
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