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From: Zhang Yi <yi.zhang@huaweicloud.com>
To: linux-ext4@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org,
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Subject: [RFC PATCH 15/18] ext4: writeback partial blocks before zero range
Date: Thu, 23 Nov 2023 20:51:17 +0800
Message-Id: <20231123125121.4064694-16-yi.zhang@huaweicloud.com>
In-Reply-To: <20231123125121.4064694-1-yi.zhang@huaweicloud.com>
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From: Zhang Yi <yi.zhang@huawei.com>

If we zero partial blocks, iomap_zero_iter() will skip zeroing out if
the srcmap is IOMAP_UNWRITTEN, it works fine in xfs because this type
means the block is pure unwritten, doesn't contain any delayed data,
but in ext4, IOMAP_UNWRITTEN may contain delayed data, it may hard to
change the definition of this flag in ext4, so just writeback partial
blocks firstly, make sure it becomes IOMAP_MAPPED.

Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
---
 fs/ext4/extents.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 52bad225e3c8..b502edcf014b 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4576,6 +4576,15 @@ static long ext4_zero_range(struct file *file, loff_t offset,
 		if (ret)
 			goto out_mutex;
 
+		ret = filemap_write_and_wait_range(mapping,
+				round_down(offset, 1 << blkbits), offset);
+		if (ret)
+			goto out_mutex;
+
+		ret = filemap_write_and_wait_range(mapping, offset + len,
+				round_up((offset + len), 1 << blkbits));
+		if (ret)
+			goto out_mutex;
 	}
 
 	/* Zero range excluding the unaligned edges */
-- 
2.39.2