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From: Matthew Wilcox <willy@infradead.org>
To: Christoph Hellwig <hch@infradead.org>
Cc: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>,
	djwong@kernel.org, brauner@kernel.org, david@fromorbit.com,
	chandan.babu@oracle.com, akpm@linux-foundation.org,
	linux-fsdevel@vger.kernel.org, hare@suse.de,
	linux-kernel@vger.kernel.org, linux-mm@kvack.org,
	linux-xfs@vger.kernel.org, mcgrof@kernel.org,
	gost.dev@samsung.com, p.raghav@samsung.com
Subject: Re: [PATCH v4 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size
Date: Sat, 27 Apr 2024 04:26:44 +0100	[thread overview]
Message-ID: <ZixwdKxqYWq4-rxd@casper.infradead.org> (raw)
In-Reply-To: <ZitIK5OnR7ZNY0IG@infradead.org>

On Thu, Apr 25, 2024 at 11:22:35PM -0700, Christoph Hellwig wrote:
> On Thu, Apr 25, 2024 at 01:37:42PM +0200, Pankaj Raghav (Samsung) wrote:
> > From: Pankaj Raghav <p.raghav@samsung.com>
> > 
> > iomap_dio_zero() will pad a fs block with zeroes if the direct IO size
> > < fs block size. iomap_dio_zero() has an implicit assumption that fs block
> > size < page_size. This is true for most filesystems at the moment.
> > 
> > If the block size > page size, this will send the contents of the page
> > next to zero page(as len > PAGE_SIZE) to the underlying block device,
> > causing FS corruption.
> > 
> > iomap is a generic infrastructure and it should not make any assumptions
> > about the fs block size and the page size of the system.
> 
> So what happened to the plan to making huge_zero_page a folio and have

There's a series of commits in linux-mm with the titles:

      sparc: use is_huge_zero_pmd()
      mm: add is_huge_zero_folio()
      mm: add pmd_folio()
      mm: convert migrate_vma_collect_pmd to use a folio
      mm: convert huge_zero_page to huge_zero_folio
      mm: convert do_huge_pmd_anonymous_page to huge_zero_folio
      dax: use huge_zero_folio
      mm: rename mm_put_huge_zero_page to mm_put_huge_zero_folio

> it available for non-hugetlb setups?  Not only would this be cleaner
> and more efficient, but it would actually work for the case where you'd
> have to zero more than 1MB on a 4k PAGE_SIZE system, which doesn't
> seem impossible with 2MB folios.

It is available for non-hugetlb setups.  It is however allocated on
demand, so it might not be available.

  parent reply	other threads:[~2024-04-27  3:26 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-25 11:37 [PATCH v4 00/11] enable bs > ps in XFS Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 01/11] readahead: rework loop in page_cache_ra_unbounded() Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 02/11] fs: Allow fine-grained control of folio sizes Pankaj Raghav (Samsung)
2024-04-25 18:07   ` Hannes Reinecke
2024-04-26 15:09   ` Darrick J. Wong
2024-04-25 11:37 ` [PATCH v4 03/11] filemap: allocate mapping_min_order folios in the page cache Pankaj Raghav (Samsung)
2024-04-25 19:04   ` Hannes Reinecke
2024-04-26 15:12   ` Darrick J. Wong
2024-04-28 20:59     ` Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 04/11] readahead: allocate folios with mapping_min_order in readahead Pankaj Raghav (Samsung)
2024-04-25 18:53   ` Matthew Wilcox
2024-04-25 11:37 ` [PATCH v4 05/11] mm: do not split a folio if it has minimum folio order requirement Pankaj Raghav (Samsung)
2024-04-25 20:10   ` Matthew Wilcox
2024-04-26  0:47     ` Luis Chamberlain
2024-04-26 23:46       ` Luis Chamberlain
2024-04-28  0:57         ` Luis Chamberlain
2024-04-29  3:56           ` Luis Chamberlain
2024-04-29 14:29             ` Zi Yan
2024-04-30  0:31               ` Luis Chamberlain
2024-04-30  0:49                 ` Luis Chamberlain
2024-04-30  2:43                 ` Zi Yan
2024-04-30 19:27                   ` Luis Chamberlain
2024-05-01  4:13                     ` Matthew Wilcox
2024-05-01 14:28                       ` Matthew Wilcox
2024-04-26 15:49     ` Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 06/11] filemap: cap PTE range to be created to i_size in folio_map_range() Pankaj Raghav (Samsung)
2024-04-25 20:24   ` Matthew Wilcox
2024-04-26 12:54     ` Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 07/11] iomap: fix iomap_dio_zero() for fs bs > system page size Pankaj Raghav (Samsung)
2024-04-26  6:22   ` Christoph Hellwig
2024-04-26 11:43     ` Pankaj Raghav (Samsung)
2024-04-27  5:12       ` Christoph Hellwig
2024-04-29 21:02         ` Pankaj Raghav (Samsung)
2024-04-27  3:26     ` Matthew Wilcox [this message]
2024-04-27  4:52       ` Christoph Hellwig
2024-04-25 11:37 ` [PATCH v4 08/11] xfs: use kvmalloc for xattr buffers Pankaj Raghav (Samsung)
2024-04-26 15:18   ` Darrick J. Wong
2024-04-28 21:06     ` Pankaj Raghav (Samsung)
2024-04-25 11:37 ` [PATCH v4 09/11] xfs: expose block size in stat Pankaj Raghav (Samsung)
2024-04-26 15:15   ` Darrick J. Wong
2024-04-25 11:37 ` [PATCH v4 10/11] xfs: make the calculation generic in xfs_sb_validate_fsb_count() Pankaj Raghav (Samsung)
2024-04-26 15:16   ` Darrick J. Wong
2024-04-25 11:37 ` [PATCH v4 11/11] xfs: enable block size larger than page size support Pankaj Raghav (Samsung)
2024-04-26 15:18   ` Darrick J. Wong
2024-04-27  4:42 ` [PATCH v4 00/11] enable bs > ps in XFS Ritesh Harjani
2024-04-27  5:05   ` Darrick J. Wong
2024-04-29 20:39   ` Pankaj Raghav (Samsung)

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