From: "Darrick J. Wong" <djwong@kernel.org>
To: "Pankaj Raghav (Samsung)" <kernel@pankajraghav.com>
Cc: willy@infradead.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 03/11] filemap: allocate mapping_min_order folios in the page cache
Date: Fri, 26 Apr 2024 08:12:43 -0700 [thread overview]
Message-ID: <20240426151243.GD360919@frogsfrogsfrogs> (raw)
In-Reply-To: <20240425113746.335530-4-kernel@pankajraghav.com>
On Thu, Apr 25, 2024 at 01:37:38PM +0200, Pankaj Raghav (Samsung) wrote:
> From: Luis Chamberlain <mcgrof@kernel.org>
>
> filemap_create_folio() and do_read_cache_folio() were always allocating
> folio of order 0. __filemap_get_folio was trying to allocate higher
> order folios when fgp_flags had higher order hint set but it will default
> to order 0 folio if higher order memory allocation fails.
>
> Supporting mapping_min_order implies that we guarantee each folio in the
> page cache has at least an order of mapping_min_order. When adding new
> folios to the page cache we must also ensure the index used is aligned to
> the mapping_min_order as the page cache requires the index to be aligned
> to the order of the folio.
If we cannot find a folio of at least min_order size, what error is sent
back?
If the answer is "the same error that you get if we cannot allocate a
base page today (aka ENOMEM)", then I think I understand this enough to
say
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
--D
> Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
> Co-developed-by: Pankaj Raghav <p.raghav@samsung.com>
> Signed-off-by: Pankaj Raghav <p.raghav@samsung.com>
> ---
> mm/filemap.c | 24 +++++++++++++++++-------
> 1 file changed, 17 insertions(+), 7 deletions(-)
>
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 30de18c4fd28..f0c0cfbbd134 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -858,6 +858,8 @@ noinline int __filemap_add_folio(struct address_space *mapping,
>
> VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
> VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio);
> + VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping),
> + folio);
> mapping_set_update(&xas, mapping);
>
> if (!huge) {
> @@ -1895,8 +1897,10 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
> folio_wait_stable(folio);
> no_page:
> if (!folio && (fgp_flags & FGP_CREAT)) {
> - unsigned order = FGF_GET_ORDER(fgp_flags);
> + unsigned int min_order = mapping_min_folio_order(mapping);
> + unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags));
> int err;
> + index = mapping_align_start_index(mapping, index);
>
> if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
> gfp |= __GFP_WRITE;
> @@ -1936,7 +1940,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
> break;
> folio_put(folio);
> folio = NULL;
> - } while (order-- > 0);
> + } while (order-- > min_order);
>
> if (err == -EEXIST)
> goto repeat;
> @@ -2425,13 +2429,16 @@ static int filemap_update_page(struct kiocb *iocb,
> }
>
> static int filemap_create_folio(struct file *file,
> - struct address_space *mapping, pgoff_t index,
> + struct address_space *mapping, loff_t pos,
> struct folio_batch *fbatch)
> {
> struct folio *folio;
> int error;
> + unsigned int min_order = mapping_min_folio_order(mapping);
> + pgoff_t index;
>
> - folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0);
> + folio = filemap_alloc_folio(mapping_gfp_mask(mapping),
> + min_order);
> if (!folio)
> return -ENOMEM;
>
> @@ -2449,6 +2456,8 @@ static int filemap_create_folio(struct file *file,
> * well to keep locking rules simple.
> */
> filemap_invalidate_lock_shared(mapping);
> + /* index in PAGE units but aligned to min_order number of pages. */
> + index = (pos >> (PAGE_SHIFT + min_order)) << min_order;
> error = filemap_add_folio(mapping, folio, index,
> mapping_gfp_constraint(mapping, GFP_KERNEL));
> if (error == -EEXIST)
> @@ -2509,8 +2518,7 @@ static int filemap_get_pages(struct kiocb *iocb, size_t count,
> if (!folio_batch_count(fbatch)) {
> if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
> return -EAGAIN;
> - err = filemap_create_folio(filp, mapping,
> - iocb->ki_pos >> PAGE_SHIFT, fbatch);
> + err = filemap_create_folio(filp, mapping, iocb->ki_pos, fbatch);
> if (err == AOP_TRUNCATED_PAGE)
> goto retry;
> return err;
> @@ -3708,9 +3716,11 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
> repeat:
> folio = filemap_get_folio(mapping, index);
> if (IS_ERR(folio)) {
> - folio = filemap_alloc_folio(gfp, 0);
> + folio = filemap_alloc_folio(gfp,
> + mapping_min_folio_order(mapping));
> if (!folio)
> return ERR_PTR(-ENOMEM);
> + index = mapping_align_start_index(mapping, index);
> err = filemap_add_folio(mapping, folio, index, gfp);
> if (unlikely(err)) {
> folio_put(folio);
> --
> 2.34.1
>
>
next prev parent reply other threads:[~2024-04-26 15:12 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 [this message]
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
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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