2014-07-15 01:39:37

by Chao Yu

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 <[email protected]>
---
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

2014-07-15 14:35:28

by Jan Kara

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

On Tue 15-07-14 09:38:51, Chao Yu wrote:
> 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.
Thanks! I've merged the patch.

Honza
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> 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
>
>
--
Jan Kara <[email protected]>
SUSE Labs, CR