2023-05-25 06:42:59

by Yue Hu

Subject: [PATCH] erofs: don't calculate new start when expanding read length

From: Yue Hu <[email protected]>

We only expand the trailing edge and not the leading edge. So no need
to obtain new start again. Let's use the existing ->headoffset instead.

Signed-off-by: Yue Hu <[email protected]>
---
fs/erofs/zdata.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index 874fee35af32..bab8dcb8e848 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -1828,26 +1828,24 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
{
struct inode *inode = f->inode;
struct erofs_map_blocks *map = &f->map;
- erofs_off_t cur, end;
+ erofs_off_t cur, end, headoffset = f->headoffset;
int err;

if (backmost) {
if (rac)
- end = f->headoffset + readahead_length(rac) - 1;
+ end = headoffset + readahead_length(rac) - 1;
else
- end = f->headoffset + PAGE_SIZE - 1;
+ end = headoffset + PAGE_SIZE - 1;
map->m_la = end;
err = z_erofs_map_blocks_iter(inode, map,
EROFS_GET_BLOCKS_READMORE);
if (err)
return;

- /* expend ra for the trailing edge if readahead */
+ /* expand ra for the trailing edge if readahead */
if (rac) {
- loff_t newstart = readahead_pos(rac);
-
cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
- readahead_expand(rac, newstart, cur - newstart);
+ readahead_expand(rac, headoffset, cur - headoffset);
return;
}
end = round_up(end, PAGE_SIZE);
--
2.17.1

2023-05-25 06:49:09

by Gao Xiang

Subject: Re: [PATCH] erofs: don't calculate new start when expanding read length

On 2023/5/25 22:51, Yue Hu wrote:
> From: Yue Hu <[email protected]>
>
> We only expand the trailing edge and not the leading edge. So no need
> to obtain new start again. Let's use the existing ->headoffset instead.
>
> Signed-off-by: Yue Hu <[email protected]>
> ---
> fs/erofs/zdata.c | 12 +++++-------
> 1 file changed, 5 insertions(+), 7 deletions(-)
>
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index 874fee35af32..bab8dcb8e848 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -1828,26 +1828,24 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
> {
> struct inode *inode = f->inode;
> struct erofs_map_blocks *map = &f->map;
> - erofs_off_t cur, end;
> + erofs_off_t cur, end, headoffset = f->headoffset;


That is not quite useful, or could you merge this info the original patch?

Thanks,
Gao Xiang

> int err;
>
> if (backmost) {
> if (rac)
> - end = f->headoffset + readahead_length(rac) - 1;
> + end = headoffset + readahead_length(rac) - 1;
> else
> - end = f->headoffset + PAGE_SIZE - 1;
> + end = headoffset + PAGE_SIZE - 1;
> map->m_la = end;
> err = z_erofs_map_blocks_iter(inode, map,
> EROFS_GET_BLOCKS_READMORE);
> if (err)
> return;
>
> - /* expend ra for the trailing edge if readahead */
> + /* expand ra for the trailing edge if readahead */
> if (rac) {
> - loff_t newstart = readahead_pos(rac);
> -
> cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
> - readahead_expand(rac, newstart, cur - newstart);
> + readahead_expand(rac, headoffset, cur - headoffset);
> return;
> }
> end = round_up(end, PAGE_SIZE);

2023-05-25 07:05:37

by Yue Hu

Subject: Re: [PATCH] erofs: don't calculate new start when expanding read length

On Thu, 25 May 2023 13:56:14 +0800
Gao Xiang <[email protected]> wrote:

> On 2023/5/25 22:51, Yue Hu wrote:
> > From: Yue Hu <[email protected]>
> >
> > We only expand the trailing edge and not the leading edge. So no need
> > to obtain new start again. Let's use the existing ->headoffset instead.
> >
> > Signed-off-by: Yue Hu <[email protected]>
> > ---
> > fs/erofs/zdata.c | 12 +++++-------
> > 1 file changed, 5 insertions(+), 7 deletions(-)
> >
> > diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> > index 874fee35af32..bab8dcb8e848 100644
> > --- a/fs/erofs/zdata.c
> > +++ b/fs/erofs/zdata.c
> > @@ -1828,26 +1828,24 @@ static void z_erofs_pcluster_readmore(struct z_erofs_decompress_frontend *f,
> > {
> > struct inode *inode = f->inode;
> > struct erofs_map_blocks *map = &f->map;
> > - erofs_off_t cur, end;
> > + erofs_off_t cur, end, headoffset = f->headoffset;
>
>
> That is not quite useful, or could you merge this info the original patch?

Okay, i will do the merge later.

>
> Thanks,
> Gao Xiang
>
> > int err;
> >
> > if (backmost) {
> > if (rac)
> > - end = f->headoffset + readahead_length(rac) - 1;
> > + end = headoffset + readahead_length(rac) - 1;
> > else
> > - end = f->headoffset + PAGE_SIZE - 1;
> > + end = headoffset + PAGE_SIZE - 1;
> > map->m_la = end;
> > err = z_erofs_map_blocks_iter(inode, map,
> > EROFS_GET_BLOCKS_READMORE);
> > if (err)
> > return;
> >
> > - /* expend ra for the trailing edge if readahead */
> > + /* expand ra for the trailing edge if readahead */
> > if (rac) {
> > - loff_t newstart = readahead_pos(rac);
> > -
> > cur = round_up(map->m_la + map->m_llen, PAGE_SIZE);
> > - readahead_expand(rac, newstart, cur - newstart);
> > + readahead_expand(rac, headoffset, cur - headoffset);
> > return;
> > }
> > end = round_up(end, PAGE_SIZE);