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From: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
To: <linux-kernel@vger.kernel.org>, <linux-xfs@vger.kernel.org>,
	<linux-nvdimm@lists.01.org>, <linux-fsdevel@vger.kernel.org>
Cc: jack@suse.cz, darrick.wong@oracle.com, david@fromorbit.com,
	ocfs2-devel@oss.oracle.com, viro@zeniv.linux.org.uk,
	Goldwyn Rodrigues <rgoldwyn@suse.com>,
	dan.j.williams@intel.com, linux-btrfs@vger.kernel.org
Subject: [Ocfs2-devel] [PATCH 2/7] fsdax: Introduce dax_copy_edges() for CoW
Date: Mon, 8 Feb 2021 01:09:19 +0800	[thread overview]
Message-ID: <20210207170924.2933035-3-ruansy.fnst@cn.fujitsu.com> (raw)
In-Reply-To: <20210207170924.2933035-1-ruansy.fnst@cn.fujitsu.com>

dax_copy_edges() is a helper functions performs a copy from one part of
the device to another for data not page aligned.

Signed-off-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
Signed-off-by: Shiyang Ruan <ruansy.fnst@cn.fujitsu.com>
---
 fs/dax.c | 41 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 41 insertions(+)

diff --git a/fs/dax.c b/fs/dax.c
index b012b2db7ba2..ea4e8a434900 100644
--- a/fs/dax.c
+++ b/fs/dax.c
@@ -1038,6 +1038,47 @@ static int dax_iomap_direct_access(struct iomap *iomap, loff_t pos, size_t size,
 	return rc;
 }
 
+/*
+ * Copies the part of the pages not included in the write, but required for CoW
+ * because offset/offset+length are not page aligned.
+ */
+static int dax_copy_edges(loff_t pos, loff_t length, struct iomap *srcmap,
+			  void *daddr, bool pmd)
+{
+	size_t page_size = pmd ? PMD_SIZE : PAGE_SIZE;
+	loff_t offset = pos & (page_size - 1);
+	size_t size = ALIGN(offset + length, page_size);
+	loff_t end = pos + length;
+	loff_t pg_end = round_up(end, page_size);
+	void *saddr = 0;
+	int ret = 0;
+
+	ret = dax_iomap_direct_access(srcmap, pos, size, &saddr, NULL);
+	if (ret)
+		return ret;
+	/*
+	 * Copy the first part of the page
+	 * Note: we pass offset as length
+	 */
+	if (offset) {
+		if (saddr)
+			ret = copy_mc_to_kernel(daddr, saddr, offset);
+		else
+			memset(daddr, 0, offset);
+	}
+
+	/* Copy the last part of the range */
+	if (end < pg_end) {
+		if (saddr)
+			ret = copy_mc_to_kernel(daddr + offset + length,
+			       saddr + offset + length,	pg_end - end);
+		else
+			memset(daddr + offset + length, 0, pg_end - end);
+	}
+
+	return ret;
+}
+
 /*
  * The user has performed a load from a hole in the file.  Allocating a new
  * page in the file would cause excessive storage usage for workloads with
-- 
2.30.0




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  parent reply	other threads:[~2021-02-08 16:54 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-07 17:09 [Ocfs2-devel] [PATCH 0/7] fsdax, xfs: Add reflink&dedupe support for fsdax Shiyang Ruan
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 1/7] fsdax: Output address in dax_iomap_pfn() and rename it Shiyang Ruan
2021-02-08 15:11   ` Christoph Hellwig
2021-02-22  7:44   ` Xiaoguang Wang
2021-02-23  1:32     ` [Ocfs2-devel] 回复: " ruansy.fnst
2021-02-07 17:09 ` Shiyang Ruan [this message]
2021-02-08 15:11   ` [Ocfs2-devel] [PATCH 2/7] fsdax: Introduce dax_copy_edges() for CoW Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 3/7] fsdax: Copy data before write Shiyang Ruan
2021-02-08 15:14   ` Christoph Hellwig
2021-02-09  1:53     ` Ruan Shiyang
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 4/7] fsdax: Replace mmap entry in case of CoW Shiyang Ruan
2021-02-08 15:16   ` Christoph Hellwig
2021-02-16 13:11   ` David Sterba
2021-02-17  3:06     ` Ruan Shiyang
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 5/7] fsdax: Dedup file range to use a compare function Shiyang Ruan
2021-02-08 15:19   ` Christoph Hellwig
2021-02-09  9:15     ` Ruan Shiyang
2021-02-09  9:34       ` Christoph Hellwig
2021-02-09  9:46         ` Ruan Shiyang
2021-02-10 13:19           ` Christoph Hellwig
2021-02-17  3:24             ` Ruan Shiyang
2021-02-18 16:20               ` Darrick J. Wong
2021-02-25  7:35                 ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 6/7] fs/xfs: Handle CoW for fsdax write() path Shiyang Ruan
2021-02-08 15:24   ` Christoph Hellwig
2021-02-07 17:09 ` [Ocfs2-devel] [PATCH 7/7] fs/xfs: Add dedupe support for fsdax Shiyang Ruan
2021-02-08 15:39 ` [Ocfs2-devel] [PATCH 0/7] fsdax, xfs: Add reflink&dedupe " Jan Kara
2021-02-09  1:50   ` Ruan Shiyang

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