linux-kernel - [f2fs-dev][PATCH v2] udf: avoid redundant memcpy when writing data in ICB

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Date:	Tue, 15 Jul 2014 09:38:51 +0800
From:	Chao Yu <chao2.yu@...sung.com>
To:	jack@...e.cz
Cc:	linux-kernel@...r.kernel.org
Subject: [f2fs-dev][PATCH v2] udf: avoid redundant memcpy when writing data in
 ICB

Valid data within i_size in page cache will be copied to ICB cache when we
writeback the page by invoking udf_adinicb_writepage, so the copy in
udf_adinicb_write_end is redundant.
After we remove the copy, it's better to use simple_write_end directly in
udf_adinicb_aops instead of udf_adinicb_write_end.

v2:
 o fix to remove redundant code correctly and use simple_write_end directly in
udf_adinicb_aops pointed out by Jan Kara.

Signed-off-by: Chao Yu <chao2.yu@...sung.com>
---
 fs/udf/file.c | 20 +-------------------
 1 file changed, 1 insertion(+), 19 deletions(-)

diff --git a/fs/udf/file.c b/fs/udf/file.c
index d80738f..3d06489 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -100,24 +100,6 @@ static int udf_adinicb_write_begin(struct file *file,
 	return 0;
 }
 
-static int udf_adinicb_write_end(struct file *file,
-			struct address_space *mapping,
-			loff_t pos, unsigned len, unsigned copied,
-			struct page *page, void *fsdata)
-{
-	struct inode *inode = mapping->host;
-	unsigned offset = pos & (PAGE_CACHE_SIZE - 1);
-	char *kaddr;
-	struct udf_inode_info *iinfo = UDF_I(inode);
-
-	kaddr = kmap_atomic(page);
-	memcpy(iinfo->i_ext.i_data + iinfo->i_lenEAttr + offset,
-		kaddr + offset, copied);
-	kunmap_atomic(kaddr);
-
-	return simple_write_end(file, mapping, pos, len, copied, page, fsdata);
-}
-
 static ssize_t udf_adinicb_direct_IO(int rw, struct kiocb *iocb,
 				     struct iov_iter *iter,
 				     loff_t offset)
@@ -130,7 +112,7 @@ const struct address_space_operations udf_adinicb_aops = {
 	.readpage	= udf_adinicb_readpage,
 	.writepage	= udf_adinicb_writepage,
 	.write_begin	= udf_adinicb_write_begin,
-	.write_end	= udf_adinicb_write_end,
+	.write_end	= simple_write_end,
 	.direct_IO	= udf_adinicb_direct_IO,
 };
 
-- 
2.0.1.474.g72c7794


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