From patchwork Thu Jul 30 01:19:01 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yu Kuai X-Patchwork-Id: 11692123 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 2E7DE1392 for ; Thu, 30 Jul 2020 01:18:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1C4542074B for ; Thu, 30 Jul 2020 01:18:58 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726341AbgG3BS5 (ORCPT ); Wed, 29 Jul 2020 21:18:57 -0400 Received: from szxga07-in.huawei.com ([45.249.212.35]:39260 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725851AbgG3BS5 (ORCPT ); Wed, 29 Jul 2020 21:18:57 -0400 Received: from DGGEMS403-HUB.china.huawei.com (unknown [172.30.72.59]) by Forcepoint Email with ESMTP id 4CD56A7A3968656C05A9; Thu, 30 Jul 2020 09:18:54 +0800 (CST) Received: from huawei.com (10.175.127.227) by DGGEMS403-HUB.china.huawei.com (10.3.19.203) with Microsoft SMTP Server id 14.3.487.0; Thu, 30 Jul 2020 09:18:45 +0800 From: Yu Kuai To: , CC: , , , , Subject: [RFC PATCH] iomap: add support to track dirty state of sub pages Date: Thu, 30 Jul 2020 09:19:01 +0800 Message-ID: <20200730011901.2840886-1-yukuai3@huawei.com> X-Mailer: git-send-email 2.25.4 MIME-Version: 1.0 X-Originating-IP: [10.175.127.227] X-CFilter-Loop: Reflected Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org commit 9dc55f1389f9 ("iomap: add support for sub-pagesize buffered I/O without buffer heads") replace the per-block structure buffer_head with the per-page structure iomap_page. However, iomap_page can't track the dirty state of sub pages, which will cause performance issue since sub pages will be writeback even if they are not dirty. For example, if block size is 4k and page size is 64k: dd if=/dev/zero of=testfile bs=4k count=16 oflag=sync With buffer_head implementation, the above dd cmd will writeback 4k in each round. However, with iomap_page implementation, the range of writeback in each round is from the start of the page to the end offset we just wrote. Thus add support to track dirty state for sub pages in iomap_page. Signed-off-by: Yu Kuai --- fs/iomap/buffered-io.c | 51 +++++++++++++++++++++++++++++++++++++++++- 1 file changed, 50 insertions(+), 1 deletion(-) diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c index bcfc288dba3f..ac2676146b98 100644 --- a/fs/iomap/buffered-io.c +++ 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; DECLARE_BITMAP(uptodate, PAGE_SIZE / 512); + DECLARE_BITMAP(dirty, PAGE_SIZE / 512); }; static inline struct iomap_page *to_iomap_page(struct page *page) @@ -53,7 +55,9 @@ iomap_page_create(struct inode *inode, struct page *page) atomic_set(&iop->read_count, 0); atomic_set(&iop->write_count, 0); spin_lock_init(&iop->uptodate_lock); + spin_lock_init(&iop->dirty_lock); bitmap_zero(iop->uptodate, PAGE_SIZE / SECTOR_SIZE); + bitmap_zero(iop->dirty, PAGE_SIZE / SECTOR_SIZE); /* * migrate_page_move_mapping() assumes that pages with private data have @@ -135,6 +139,44 @@ iomap_adjust_read_range(struct inode *inode, struct iomap_page *iop, *lenp = plen; } +static void +iomap_iop_set_or_clear_range_dirty( + struct page *page, + unsigned int off, + unsigned int len, + bool is_set) +{ + struct iomap_page *iop = to_iomap_page(page); + struct inode *inode = page->mapping->host; + unsigned int first = off >> inode->i_blkbits; + unsigned int last = (off + len - 1) >> inode->i_blkbits; + unsigned long flags; + unsigned int i; + + spin_lock_irqsave(&iop->dirty_lock, flags); + for (i = first; i <= last; i++) + if (is_set) + set_bit(i, iop->dirty); + else + clear_bit(i, iop->dirty); + spin_unlock_irqrestore(&iop->dirty_lock, flags); +} + +static void +iomap_set_or_clear_range_dirty( + struct page *page, + unsigned int off, + unsigned int len, + bool is_set) +{ + if (PageError(page)) + return; + + if (page_has_private(page)) + iomap_iop_set_or_clear_range_dirty( + page, off, len, is_set); +} + static void iomap_iop_set_range_uptodate(struct page *page, unsigned off, unsigned len) { @@ -705,6 +747,8 @@ __iomap_write_end(struct inode *inode, loff_t pos, unsigned len, if (unlikely(copied < len && !PageUptodate(page))) return 0; iomap_set_range_uptodate(page, offset_in_page(pos), len); + iomap_set_or_clear_range_dirty( + page, offset_in_page(pos), len, true); iomap_set_page_dirty(page); return copied; } @@ -1030,6 +1074,8 @@ iomap_page_mkwrite_actor(struct inode *inode, loff_t pos, loff_t length, WARN_ON_ONCE(!PageUptodate(page)); iomap_page_create(inode, page); set_page_dirty(page); + iomap_set_or_clear_range_dirty( + page, offset_in_page(pos), length, true); } return length; @@ -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; error = wpc->ops->map_blocks(wpc, inode, file_offset); @@ -1435,6 +1482,8 @@ iomap_writepage_map(struct iomap_writepage_ctx *wpc, */ set_page_writeback_keepwrite(page); } else { + iomap_set_or_clear_range_dirty( + page, 0, end_offset - page_offset(page) + 1, false); clear_page_dirty_for_io(page); set_page_writeback(page); }