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[RFC,v2,21/25] ext4: writeback partial blocks before zero range

Message ID 20240102123918.799062-22-yi.zhang@huaweicloud.com (mailing list archive)
State New
Headers show
Series ext4: use iomap for regular file's buffered IO path and enable large foilo | expand

Commit Message

Zhang Yi Jan. 2, 2024, 12:39 p.m. UTC 
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. For now we cannot
simply change the meaning of this flag in ext4, so just writeback
partial blocks from the beginning, make sure it becomes IOMAP_MAPPED
before zeroing out.

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

diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
index 67ff75108cd1..d98c50472a42 100644
--- a/fs/ext4/extents.c
+++ b/fs/ext4/extents.c
@@ -4606,6 +4606,15 @@  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 */