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From: Dan Williams <dan.j.williams@intel.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Jan Kara <jack@suse.cz>,
	"Darrick J. Wong" <darrick.wong@oracle.com>,
	linux-nvdimm <linux-nvdimm@lists.01.org>,
	Dave Chinner <david@fromorbit.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	linux-xfs <linux-xfs@vger.kernel.org>,
	linux-fsdevel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH v6 12/15] xfs: require mmap lock for xfs_break_layouts()
Date: Fri, 16 Mar 2018 12:10:05 -0700	[thread overview]
Message-ID: <CAPcyv4iii7i-W-NvX+PaPfwATuWJamD38cdNUHvP=Cn-5vL3Ww@mail.gmail.com> (raw)
In-Reply-To: <20180316190443.GF3671@lst.de>

On Fri, Mar 16, 2018 at 12:04 PM, Christoph Hellwig <hch@lst.de> wrote:
> On Thu, Mar 15, 2018 at 08:52:29AM -0700, Dan Williams wrote:
>> In preparation for adding coordination between truncate operations and
>> busy dax-pages, extend xfs_break_layouts() to assume it must be called
>> with the mmap lock held. This locking scheme will be required for
>> coordinating the break of 'dax layouts' (non-idle dax (ZONE_DEVICE)
>> pages mapped into the file's address space).
>
> This requirement wasn't really there in the last series, why do we
> require it now?

It seems I misinterpreted your feedback.

>
> As far as I can tell all we'd need is to just drop this assert:
>
>> -     ASSERT(xfs_isilocked(ip, XFS_IOLOCK_SHARED|XFS_IOLOCK_EXCL));
>> +     ASSERT(xfs_isilocked(ip, XFS_IOLOCK_SHARED | XFS_IOLOCK_EXCL
>> +                             | XFS_MMAPLOCK_EXCL));
>
> entirely.
>
>>       while ((error = break_layout(inode, false) == -EWOULDBLOCK)) {
>>               xfs_iunlock(ip, *iolock);
>>               error = break_layout(inode, true);
>> -             *iolock = XFS_IOLOCK_EXCL;
>> +             *iolock &= ~XFS_IOLOCK_SHARED;
>> +             *iolock |= XFS_IOLOCK_EXCL;
>>               xfs_ilock(ip, *iolock);
>
> And take this one hunk from your patch.
>
> To enable the DAX use case.

Yeah, that looks good to me.
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  reply	other threads:[~2018-03-16 19:03 UTC|newest]

Thread overview: 40+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-15 15:51 [PATCH v6 00/15] dax: fix dma vs truncate/hole-punch Dan Williams
2018-03-15 15:51 ` [PATCH v6 01/15] dax: store pfns in the radix Dan Williams
2018-03-15 15:51 ` [PATCH v6 02/15] fs, dax: prepare for dax-specific address_space_operations Dan Williams
2018-03-16 18:59   ` Christoph Hellwig
2018-03-15 15:51 ` [PATCH v6 03/15] block, dax: remove dead code in blkdev_writepages() Dan Williams
2018-03-16 18:59   ` Christoph Hellwig
2018-03-15 15:51 ` [PATCH v6 04/15] xfs, dax: introduce xfs_dax_aops Dan Williams
2018-03-16 19:00   ` Christoph Hellwig
2018-03-15 15:51 ` [PATCH v6 05/15] ext4, dax: introduce ext4_dax_aops Dan Williams
2018-03-15 15:51 ` [PATCH v6 06/15] ext2, dax: introduce ext2_dax_aops Dan Williams
2018-03-18  4:02   ` kbuild test robot
2018-03-18  4:02   ` [RFC PATCH] ext2, dax: ext2_dax_aops can be static kbuild test robot
2018-03-15 15:52 ` [PATCH v6 07/15] fs, dax: use page->mapping to warn if truncate collides with a busy page Dan Williams
2018-03-18  6:26   ` kbuild test robot
2018-03-15 15:52 ` [PATCH v6 08/15] mm, dax: enable filesystems to trigger dev_pagemap ->page_free callbacks Dan Williams
2018-03-15 15:52 ` [PATCH v6 09/15] mm, dev_pagemap: introduce CONFIG_DEV_PAGEMAP_OPS Dan Williams
2018-03-15 15:52 ` [PATCH v6 10/15] memremap: mark devm_memremap_pages() EXPORT_SYMBOL_GPL Dan Williams
2018-03-15 15:52 ` [PATCH v6 11/15] mm, fs, dax: handle layout changes to pinned dax mappings Dan Williams
2018-03-16 19:01   ` Christoph Hellwig
2018-03-17 22:14   ` kbuild test robot
2018-03-15 15:52 ` [PATCH v6 12/15] xfs: require mmap lock for xfs_break_layouts() Dan Williams
2018-03-16 19:04   ` Christoph Hellwig
2018-03-16 19:10     ` Dan Williams [this message]
2018-03-19 17:33   ` Darrick J. Wong
2018-03-19 17:57     ` Dan Williams
2018-03-19 18:19       ` Darrick J. Wong
2018-03-19 18:34         ` Dan Williams
2018-03-19 19:45       ` Christoph Hellwig
2018-03-19 20:10         ` Dan Williams
2018-03-19 21:14           ` Christoph Hellwig
2018-03-15 15:52 ` [PATCH v6 13/15] xfs: communicate lock drop events from xfs_break_layouts() Dan Williams
2018-03-16 19:08   ` Christoph Hellwig
2018-03-15 15:52 ` [PATCH v6 14/15] xfs: prepare xfs_break_layouts() for another layout type Dan Williams
2018-03-16 19:08   ` Christoph Hellwig
2018-03-19 17:45   ` Darrick J. Wong
2018-03-19 18:09     ` Dan Williams
2018-03-15 15:52 ` [PATCH v6 15/15] xfs, dax: introduce xfs_break_dax_layouts() Dan Williams
2018-03-16 19:09   ` Christoph Hellwig
2018-03-17 22:11   ` kbuild test robot
2018-03-17 23:47   ` kbuild test robot

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