erofs: enable large folio in device-based mode

  Enable large folio in device-based mode. Then the radahead routine will
pass down large folio containing multiple pages.

Enable this feature for non-compressed format for now, until the
compression part supports large folio later.

Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
---
I have tested it under workload of Linux compiling. I know it's not a
perfect workload testing this feature, because large folio is less
likely hit in this case since source files are generally small. But I
indeed observed large folios (e.g. 16 pages) by peeking
readahead_count(rac) in erofs_readahead().
---
 fs/erofs/inode.c | 2 ++
 1 file changed, 2 insertions(+)
  

On 11/10/22 3:40 PM, Jingbo Xu wrote:
> Enable large folio in device-based mode. Then the radahead routine will
> pass down large folio containing multiple pages.
> 
> Enable this feature for non-compressed format for now, until the
> compression part supports large folio later.
> 
> Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
> ---
> I have tested it under workload of Linux compiling. I know it's not a
> perfect workload testing this feature, because large folio is less
> likely hit in this case since source files are generally small. But I
> indeed observed large folios (e.g. 16 pages) by peeking
> readahead_count(rac) in erofs_readahead().

Sorry, readahead_count(rac) returns the whole number of pages inside the
rac, which can not prove large folio passed in.

I retired later and observed large folio (e.g. with order 2) by peeking
folio_order(ctx->cur_folio) inside iomap_readahead_iter()

> ---
>  fs/erofs/inode.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> index ad2a82f2eb4c..e457b8a59ee7 100644
> --- a/fs/erofs/inode.c
> +++ b/fs/erofs/inode.c
> @@ -295,6 +295,8 @@ static int erofs_fill_inode(struct inode *inode)
>  		goto out_unlock;
>  	}
>  	inode->i_mapping->a_ops = &erofs_raw_access_aops;
> +	if (!erofs_is_fscache_mode(inode->i_sb))
> +		mapping_set_large_folios(inode->i_mapping);
>  #ifdef CONFIG_EROFS_FS_ONDEMAND
>  	if (erofs_is_fscache_mode(inode->i_sb))
>  		inode->i_mapping->a_ops = &erofs_fscache_access_aops;
  

Hi,

On Thu, Nov 10, 2022 at 03:59:14PM +0800, JeffleXu wrote:
> 
> 
> On 11/10/22 3:40 PM, Jingbo Xu wrote:
> > Enable large folio in device-based mode. Then the radahead routine will
> > pass down large folio containing multiple pages.
> > 
> > Enable this feature for non-compressed format for now, until the
> > compression part supports large folio later.
> > 
> > Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
> > ---
> > I have tested it under workload of Linux compiling. I know it's not a
> > perfect workload testing this feature, because large folio is less
> > likely hit in this case since source files are generally small. But I
> > indeed observed large folios (e.g. 16 pages) by peeking
> > readahead_count(rac) in erofs_readahead().
> 
> Sorry, readahead_count(rac) returns the whole number of pages inside the
> rac, which can not prove large folio passed in.
> 
> I retired later and observed large folio (e.g. with order 2) by peeking
> folio_order(ctx->cur_folio) inside iomap_readahead_iter()

I will test it as well after I send out all bug fixes for this cycle.

Thanks,
Gao Xiang

> 
> > ---
> >  fs/erofs/inode.c | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> > diff --git a/fs/erofs/inode.c b/fs/erofs/inode.c
> > index ad2a82f2eb4c..e457b8a59ee7 100644
> > --- a/fs/erofs/inode.c
> > +++ b/fs/erofs/inode.c
> > @@ -295,6 +295,8 @@ static int erofs_fill_inode(struct inode *inode)
> >  		goto out_unlock;
> >  	}
> >  	inode->i_mapping->a_ops = &erofs_raw_access_aops;
> > +	if (!erofs_is_fscache_mode(inode->i_sb))
> > +		mapping_set_large_folios(inode->i_mapping);
> >  #ifdef CONFIG_EROFS_FS_ONDEMAND
> >  	if (erofs_is_fscache_mode(inode->i_sb))
> >  		inode->i_mapping->a_ops = &erofs_fscache_access_aops;
> 
> -- 
> Thanks,
> Jingbo
  

On Fri, Nov 11, 2022 at 02:36:25PM +0800, Gao Xiang wrote:
> Hi,
> 
> On Thu, Nov 10, 2022 at 03:59:14PM +0800, JeffleXu wrote:
> > 
> > 
> > On 11/10/22 3:40 PM, Jingbo Xu wrote:
> > > Enable large folio in device-based mode. Then the radahead routine will
> > > pass down large folio containing multiple pages.
> > > 
> > > Enable this feature for non-compressed format for now, until the
> > > compression part supports large folio later.
> > > 
> > > Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
> > > ---
> > > I have tested it under workload of Linux compiling. I know it's not a
> > > perfect workload testing this feature, because large folio is less
> > > likely hit in this case since source files are generally small. But I
> > > indeed observed large folios (e.g. 16 pages) by peeking
> > > readahead_count(rac) in erofs_readahead().
> > 
> > Sorry, readahead_count(rac) returns the whole number of pages inside the
> > rac, which can not prove large folio passed in.
> > 
> > I retired later and observed large folio (e.g. with order 2) by peeking
> > folio_order(ctx->cur_folio) inside iomap_readahead_iter()
> 
> I will test it as well after I send out all bug fixes for this cycle.

I've updated the subject and commit message as:
"
erofs: enable large folios for iomap mode
Enable large folios for iomap mode.  Then the readahead routine will
pass down large folios containing multiple pages.

Let's enable this for non-compressed format for now, until the
compression part supports large folios later.
"

Thanks,
Gao Xiang