From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
Cc: linux-xfs@vger.kernel.org, Jan Kara <jack@suse.cz>,
Matthew Wilcox <mawilcox@microsoft.com>,
Dave Chinner <david@fromorbit.com>,
Dave Hansen <dave.hansen@linux.intel.com>,
Jeff Layton <jlayton@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Christoph Hellwig <hch@lst.de>,
"J. Bruce Fields" <bfields@fieldses.org>,
Linux MM <linux-mm@kvack.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
"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 18:32:21 +0200 [thread overview]
Message-ID: <20171020163221.GB26320@lst.de> (raw)
In-Reply-To: <CAPcyv4hXCJYTkUKs6NiOp=8kgExu+bgZnVn_v+Os7fVUc2NxFg@mail.gmail.com>
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.
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Linux-nvdimm@lists.01.org
https://lists.01.org/mailman/listinfo/linux-nvdimm
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
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, Christoph Hellwig <hch@lst.de>,
"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 18:32:21 +0200 [thread overview]
Message-ID: <20171020163221.GB26320@lst.de> (raw)
In-Reply-To: <CAPcyv4hXCJYTkUKs6NiOp=8kgExu+bgZnVn_v+Os7fVUc2NxFg@mail.gmail.com>
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.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@lst.de>
To: Dan Williams <dan.j.williams@intel.com>
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, Christoph Hellwig <hch@lst.de>,
"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 18:32:21 +0200 [thread overview]
Message-ID: <20171020163221.GB26320@lst.de> (raw)
In-Reply-To: <CAPcyv4hXCJYTkUKs6NiOp=8kgExu+bgZnVn_v+Os7fVUc2NxFg@mail.gmail.com>
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.
--
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next prev parent reply other threads:[~2017-10-20 16:28 UTC|newest]
Thread overview: 143+ 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 2:38 ` Dan Williams
2017-10-20 2:38 ` Dan Williams
2017-10-20 2:38 ` Dan Williams
2017-10-20 2:39 ` [PATCH v3 01/13] dax: quiet bdev_dax_supported() Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 2:39 ` [PATCH v3 02/13] dax: require 'struct page' for filesystem dax Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 7:57 ` Christoph Hellwig
2017-10-20 7:57 ` Christoph Hellwig
2017-10-20 15:23 ` Dan Williams
2017-10-20 15:23 ` Dan Williams
2017-10-20 15:23 ` Dan Williams
2017-10-20 16:29 ` Christoph Hellwig
2017-10-20 16:29 ` Christoph Hellwig
2017-10-20 16:29 ` Christoph Hellwig
2017-10-20 16:29 ` Christoph Hellwig
2017-10-20 22:29 ` Dan Williams
2017-10-20 22:29 ` Dan Williams
2017-10-20 22:29 ` Dan Williams
2017-10-21 3:20 ` Matthew Wilcox
2017-10-21 3:20 ` Matthew Wilcox
2017-10-21 3:20 ` Matthew Wilcox
2017-10-21 4:16 ` Dan Williams
2017-10-21 4:16 ` Dan Williams
2017-10-21 4:16 ` Dan Williams
2017-10-21 8:15 ` Christoph Hellwig
2017-10-21 8:15 ` Christoph Hellwig
2017-10-21 8:15 ` Christoph Hellwig
2017-10-23 5:18 ` Martin Schwidefsky
2017-10-23 5:18 ` Martin Schwidefsky
2017-10-23 5:18 ` Martin Schwidefsky
2017-10-23 8:55 ` Dan Williams
2017-10-23 8:55 ` Dan Williams
2017-10-23 10:44 ` Martin Schwidefsky
2017-10-23 10:44 ` Martin Schwidefsky
2017-10-23 10:44 ` Martin Schwidefsky
2017-10-23 11:20 ` Dan Williams
2017-10-23 11:20 ` Dan Williams
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 ` Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 2:39 ` [PATCH v3 04/13] dax: stop using VM_HUGEPAGE " Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 2:39 ` 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 ` Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 2:39 ` [PATCH v3 06/13] dax: store pfns in the radix Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 2:39 ` 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 ` Dan Williams
2017-10-20 2:39 ` 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 ` Dan Williams
2017-10-20 2:39 ` 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 ` Dan Williams
2017-10-20 2:39 ` 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 ` Dan Williams
2017-10-20 2:39 ` 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 2:39 ` Dan Williams
2017-10-20 2:39 ` Dan Williams
2017-10-20 12:39 ` Jeffrey Layton
2017-10-20 12:39 ` Jeffrey Layton
2017-10-20 12:39 ` Jeffrey Layton
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 2:40 ` Dan Williams
2017-10-20 2:40 ` Dan Williams
2017-10-20 13:05 ` Jeff Layton
2017-10-20 13:05 ` Jeff Layton
2017-10-20 13:05 ` Jeff Layton
2017-10-20 15:42 ` Dan Williams
2017-10-20 15:42 ` Dan Williams
2017-10-20 15:42 ` Dan Williams
2017-10-20 16:32 ` Christoph Hellwig [this message]
2017-10-20 16:32 ` Christoph Hellwig
2017-10-20 16:32 ` Christoph Hellwig
2017-10-20 17:27 ` Dan Williams
2017-10-20 17:27 ` Dan Williams
2017-10-20 17:27 ` Dan Williams
2017-10-20 20:36 ` Brian Foster
2017-10-20 20:36 ` Brian Foster
2017-10-20 20:36 ` Brian Foster
2017-10-21 8:11 ` Christoph Hellwig
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 2:40 ` Dan Williams
2017-10-20 2:40 ` 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 7:47 ` Christoph Hellwig
2017-10-20 7:47 ` Christoph Hellwig
2017-10-20 7:47 ` Christoph Hellwig
2017-10-20 9:31 ` Christoph Hellwig
2017-10-20 9:31 ` Christoph Hellwig
2017-10-20 9:31 ` Christoph Hellwig
2017-10-26 10:58 ` Jan Kara
2017-10-26 10:58 ` Jan Kara
2017-10-26 10:58 ` Jan Kara
2017-10-26 10:58 ` Jan Kara
2017-10-26 23:51 ` Williams, Dan J
2017-10-26 23:51 ` Williams, Dan J
2017-10-26 23:51 ` Williams, Dan J
2017-10-26 23:51 ` Williams, Dan J
2017-10-27 6:48 ` Dave Chinner
2017-10-27 6:48 ` Dave Chinner
2017-10-27 6:48 ` Dave Chinner
2017-10-27 6:48 ` Dave Chinner
2017-10-27 6:48 ` Dave Chinner
2017-10-27 11:42 ` Dan Williams
2017-10-27 11:42 ` Dan Williams
2017-10-27 11:42 ` Dan Williams
2017-10-29 21:52 ` Dave Chinner
2017-10-29 21:52 ` Dave Chinner
2017-10-29 21:52 ` Dave Chinner
2017-10-27 6:45 ` Christoph Hellwig
2017-10-27 6:45 ` Christoph Hellwig
2017-10-27 6:45 ` Christoph Hellwig
2017-10-29 23:46 ` Dan Williams
2017-10-29 23:46 ` Dan Williams
2017-10-29 23:46 ` Dan Williams
2017-10-30 2:00 ` Dave Chinner
2017-10-30 2:00 ` Dave Chinner
2017-10-30 2:00 ` Dave Chinner
2017-10-30 2:00 ` Dave Chinner
2017-10-30 8:38 ` Jan Kara
2017-10-30 8:38 ` Jan Kara
2017-10-30 8:38 ` Jan Kara
2017-10-30 11:20 ` Dave Chinner
2017-10-30 11:20 ` Dave Chinner
2017-10-30 11:20 ` Dave Chinner
2017-10-30 11:20 ` Dave Chinner
2017-10-30 17:51 ` Dan Williams
2017-10-30 17:51 ` Dan Williams
2017-10-30 17:51 ` Dan Williams
2017-10-30 17:51 ` Dan Williams
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