From: Christoph Hellwig <hch@infradead.org>
To: Matthew Wilcox <willy@infradead.org>
Cc: linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 14/25] iomap: Support arbitrarily many blocks per page
Date: Wed, 12 Feb 2020 00:05:10 -0800 [thread overview]
Message-ID: <20200212080510.GA24497@infradead.org> (raw)
In-Reply-To: <20200212041845.25879-15-willy@infradead.org>
On Tue, Feb 11, 2020 at 08:18:34PM -0800, Matthew Wilcox wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
>
> Size the uptodate array dynamically. Now that this array is protected
> by a spinlock, we can use bitmap functions to set the bits in this array
> instead of a loop around set_bit().
>
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> ---
> fs/iomap/buffered-io.c | 27 +++++++++------------------
> 1 file changed, 9 insertions(+), 18 deletions(-)
>
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index c551a48e2a81..5e5a6b038fc3 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -22,14 +22,14 @@
> #include "../internal.h"
>
> /*
> - * Structure allocated for each page when block size < PAGE_SIZE to track
> + * Structure allocated for each page when block size < page size to track
> * sub-page uptodate status and I/O completions.
> */
> struct iomap_page {
> atomic_t read_count;
> atomic_t write_count;
> spinlock_t uptodate_lock;
> - DECLARE_BITMAP(uptodate, PAGE_SIZE / 512);
> + unsigned long uptodate[];
> };
>
> static inline struct iomap_page *to_iomap_page(struct page *page)
> @@ -45,15 +45,14 @@ static struct iomap_page *
> iomap_page_create(struct inode *inode, struct page *page)
> {
> struct iomap_page *iop = to_iomap_page(page);
> + unsigned int n, nr_blocks = i_blocks_per_page(inode, page);
>
> - if (iop || i_blocks_per_page(inode, page) <= 1)
> + if (iop || nr_blocks <= 1)
> return iop;
>
> - iop = kmalloc(sizeof(*iop), GFP_NOFS | __GFP_NOFAIL);
> - atomic_set(&iop->read_count, 0);
> - atomic_set(&iop->write_count, 0);
> + n = BITS_TO_LONGS(nr_blocks);
> + iop = kzalloc(struct_size(iop, uptodate, n), GFP_NOFS | __GFP_NOFAIL);
Nit: I don't really hink we need the n variable here, we can just
opencode the BITS_TO_LONGS in the struct_size call.
> struct inode *inode = page->mapping->host;
> unsigned first = off >> inode->i_blkbits;
> - unsigned last = (off + len - 1) >> inode->i_blkbits;
> - bool uptodate = true;
> + unsigned count = len >> inode->i_blkbits;
> unsigned long flags;
> - unsigned int i;
>
> spin_lock_irqsave(&iop->uptodate_lock, flags);
> - for (i = 0; i < i_blocks_per_page(inode, page); i++) {
> - if (i >= first && i <= last)
> - set_bit(i, iop->uptodate);
> - else if (!test_bit(i, iop->uptodate))
> - uptodate = false;
> - }
> -
> - if (uptodate)
> + bitmap_set(iop->uptodate, first, count);
> + if (bitmap_full(iop->uptodate, i_blocks_per_page(inode, page)))
> SetPageUptodate(page);
Switching to the bitmap helpers might be worthwhile prep patch that
can go in directly now that we're having the uptodate_lock.
next prev parent reply other threads:[~2020-02-12 8:05 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-12 4:18 [PATCH v2 00/25] Large pages in the page cache Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 01/25] mm: Use vm_fault error code directly Matthew Wilcox
2020-02-12 7:34 ` Christoph Hellwig
2020-02-12 4:18 ` [PATCH v2 02/25] mm: Optimise find_subpage for !THP Matthew Wilcox
2020-02-12 7:41 ` Christoph Hellwig
2020-02-12 13:02 ` Matthew Wilcox
2020-02-12 17:52 ` Christoph Hellwig
2020-02-13 13:50 ` Kirill A. Shutemov
2020-02-12 4:18 ` [PATCH v2 03/25] mm: Use VM_BUG_ON_PAGE in clear_page_dirty_for_io Matthew Wilcox
2020-02-12 7:38 ` Christoph Hellwig
2020-02-13 13:50 ` Kirill A. Shutemov
2020-02-12 4:18 ` [PATCH v2 04/25] mm: Unexport find_get_entry Matthew Wilcox
2020-02-12 7:37 ` Christoph Hellwig
2020-02-13 13:51 ` Kirill A. Shutemov
2020-02-12 4:18 ` [PATCH v2 05/25] mm: Fix documentation of FGP flags Matthew Wilcox
2020-02-12 7:42 ` Christoph Hellwig
2020-02-12 19:11 ` Matthew Wilcox
2020-02-13 14:00 ` Kirill A. Shutemov
2020-02-13 13:59 ` Kirill A. Shutemov
2020-02-13 14:34 ` Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 06/25] mm: Allow hpages to be arbitrary order Matthew Wilcox
2020-02-13 14:11 ` Kirill A. Shutemov
2020-02-13 14:30 ` Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 07/25] mm: Introduce thp_size Matthew Wilcox
2020-02-13 14:19 ` Kirill A. Shutemov
2020-02-12 4:18 ` [PATCH v2 08/25] mm: Introduce thp_order Matthew Wilcox
2020-02-13 14:20 ` Kirill A. Shutemov
2020-02-12 4:18 ` [PATCH v2 09/25] fs: Add a filesystem flag for large pages Matthew Wilcox
2020-02-12 7:43 ` Christoph Hellwig
2020-02-12 14:59 ` Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 10/25] fs: Introduce i_blocks_per_page Matthew Wilcox
2020-02-12 7:44 ` Christoph Hellwig
2020-02-12 15:05 ` Matthew Wilcox
2020-02-12 17:54 ` Christoph Hellwig
2020-02-13 15:40 ` Kirill A. Shutemov
2020-02-13 16:07 ` Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 11/25] fs: Make page_mkwrite_check_truncate thp-aware Matthew Wilcox
2020-02-13 15:44 ` Kirill A. Shutemov
2020-02-13 16:26 ` Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 12/25] mm: Add file_offset_of_ helpers Matthew Wilcox
2020-02-12 7:46 ` Christoph Hellwig
2020-02-12 4:18 ` [PATCH v2 13/25] fs: Add zero_user_large Matthew Wilcox
2020-02-14 13:52 ` Kirill A. Shutemov
2020-02-14 16:03 ` Matthew Wilcox
2020-02-18 14:16 ` Kirill A. Shutemov
2020-02-18 16:13 ` Matthew Wilcox
2020-02-18 17:10 ` Kirill A. Shutemov
2020-02-18 18:07 ` Matthew Wilcox
2020-02-21 12:42 ` Kirill A. Shutemov
2020-02-12 4:18 ` [PATCH v2 14/25] iomap: Support arbitrarily many blocks per page Matthew Wilcox
2020-02-12 8:05 ` Christoph Hellwig [this message]
2020-02-12 4:18 ` [PATCH v2 15/25] iomap: Support large pages in iomap_adjust_read_range Matthew Wilcox
2020-02-12 8:11 ` Christoph Hellwig
2020-02-12 4:18 ` [PATCH v2 16/25] iomap: Support large pages in read paths Matthew Wilcox
2020-02-12 8:13 ` Christoph Hellwig
2020-02-12 17:45 ` Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 17/25] iomap: Support large pages in write paths Matthew Wilcox
2020-02-12 8:17 ` Christoph Hellwig
2020-02-12 4:18 ` [PATCH v2 18/25] iomap: Inline data shouldn't see large pages Matthew Wilcox
2020-02-12 8:05 ` Christoph Hellwig
2020-02-12 4:18 ` [PATCH v2 19/25] xfs: Support " Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 20/25] mm: Make prep_transhuge_page return its argument Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 21/25] mm: Add __page_cache_alloc_order Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 22/25] mm: Allow large pages to be added to the page cache Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 23/25] mm: Allow large pages to be removed from " Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 24/25] mm: Add large page readahead Matthew Wilcox
2020-02-12 4:18 ` [PATCH v2 25/25] mm: Align THP mappings for non-DAX Matthew Wilcox
2020-02-12 7:50 ` Christoph Hellwig
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