linux-xfs.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Matthew Wilcox <willy@infradead.org>
To: Yu Kuai <yukuai3@huawei.com>
Cc: hch@infradead.org, darrick.wong@oracle.com,
	linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-kernel@vger.kernel.org, yi.zhang@huawei.com
Subject: Re: [RFC PATCH] iomap: add support to track dirty state of sub pages
Date: Thu, 30 Jul 2020 04:19:34 +0100	[thread overview]
Message-ID: <20200730031934.GA23808@casper.infradead.org> (raw)
In-Reply-To: <20200730011901.2840886-1-yukuai3@huawei.com>

On Thu, Jul 30, 2020 at 09:19:01AM +0800, Yu Kuai wrote:
> +++ b/fs/iomap/buffered-io.c
> @@ -29,7 +29,9 @@ struct iomap_page {
>  	atomic_t		read_count;
>  	atomic_t		write_count;
>  	spinlock_t		uptodate_lock;
> +	spinlock_t		dirty_lock;

No need for a separate spinlock.  Just rename uptodate_lock.  Maybe
'bitmap_lock'.

>  	DECLARE_BITMAP(uptodate, PAGE_SIZE / 512);
> +	DECLARE_BITMAP(dirty, PAGE_SIZE / 512);

This is inefficient and poses difficulties for the THP patchset.
Maybe let the discussion on removing the ->uptodate array finish
before posting another patch for review?

> +static void
> +iomap_iop_set_or_clear_range_dirty(
> +	struct page *page,
> +	unsigned int off,
> +	unsigned int len,
> +	bool is_set)

Please follow normal kernel programming style.  This isn't XFS.
Also 'set or clear' with a bool to indicate which to do is horrible
style.  Separate functions!

> @@ -1386,7 +1432,8 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc,
>  	for (i = 0, file_offset = page_offset(page);
>  	     i < (PAGE_SIZE >> inode->i_blkbits) && file_offset < end_offset;
>  	     i++, file_offset += len) {
> -		if (iop && !test_bit(i, iop->uptodate))
> +		if (iop && (!test_bit(i, iop->uptodate) ||
> +		    !test_bit(i, iop->dirty)))
>  			continue;

Surely we don't need to test ->uptodate here at all.  Why would we write
back a block which isn't dirty?


  parent reply	other threads:[~2020-07-30  3:19 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-30  1:19 [RFC PATCH] iomap: add support to track dirty state of sub pages Yu Kuai
2020-07-30  2:27 ` Gao Xiang
2020-07-30  3:13   ` yukuai (C)
2020-07-30  3:19 ` Matthew Wilcox [this message]
2020-07-30  3:39   ` yukuai (C)
2020-07-31  6:59   ` Christoph Hellwig

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200730031934.GA23808@casper.infradead.org \
    --to=willy@infradead.org \
    --cc=darrick.wong@oracle.com \
    --cc=hch@infradead.org \
    --cc=linux-fsdevel@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-xfs@vger.kernel.org \
    --cc=yi.zhang@huawei.com \
    --cc=yukuai3@huawei.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).