linux-kernel - Re: [PATCH 5/5] squashfs: Convert squashfs_fill

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Message-ID: <41ed0b22-099a-40dd-b7e7-1e8719241fcc@squashfs.org.uk>
Date: Tue, 14 Jan 2025 21:08:41 +0000
From: Phillip Lougher <phillip@...ashfs.org.uk>
To: "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
 linux-mm@...ck.org
Subject: Re: [PATCH 5/5] squashfs: Convert squashfs_fill_page() to take a
 folio



On 12/16/24 16:26, Matthew Wilcox (Oracle) wrote:
> squashfs_fill_page is only used in this file, so make it static.
> Use kmap_local instead of kmap_atomic, and return a bool so that
> the caller can use folio_end_read() which saves an atomic operation
> over calling folio_mark_uptodate() followed by folio_unlock().
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>

Reviewed-by: Phillip Lougher <phillip@...ashfs.org.uk>
Tested-by: Phillip Lougher <phillip@...ashfs.org.uk>

> ---
>   fs/squashfs/file.c     | 21 ++++++++++++---------
>   fs/squashfs/squashfs.h |  1 -
>   2 files changed, 12 insertions(+), 10 deletions(-)
> 
> diff --git a/fs/squashfs/file.c b/fs/squashfs/file.c
> index 1f27e8161319..d363fb26c2c8 100644
> --- a/fs/squashfs/file.c
> +++ b/fs/squashfs/file.c
> @@ -362,19 +362,21 @@ static int read_blocklist(struct inode *inode, int index, u64 *block)
>   	return squashfs_block_size(size);
>   }
>   
> -void squashfs_fill_page(struct page *page, struct squashfs_cache_entry *buffer, int offset, int avail)
> +static bool squashfs_fill_page(struct folio *folio,
> +		struct squashfs_cache_entry *buffer, size_t offset,
> +		size_t avail)
>   {
> -	int copied;
> +	size_t copied;
>   	void *pageaddr;
>   
> -	pageaddr = kmap_atomic(page);
> +	pageaddr = kmap_local_folio(folio, 0);
>   	copied = squashfs_copy_data(pageaddr, buffer, offset, avail);
>   	memset(pageaddr + copied, 0, PAGE_SIZE - copied);
> -	kunmap_atomic(pageaddr);
> +	kunmap_local(pageaddr);
>   
> -	flush_dcache_page(page);
> -	if (copied == avail)
> -		SetPageUptodate(page);
> +	flush_dcache_folio(folio);
> +
> +	return copied == avail;
>   }
>   
>   /* Copy data into page cache  */
> @@ -398,6 +400,7 @@ void squashfs_copy_cache(struct folio *folio,
>   			bytes -= PAGE_SIZE, offset += PAGE_SIZE) {
>   		struct folio *push_folio;
>   		size_t avail = buffer ? min(bytes, PAGE_SIZE) : 0;
> +		bool filled = false;
>   
>   		TRACE("bytes %zu, i %d, available_bytes %zu\n", bytes, i, avail);
>   
> @@ -412,9 +415,9 @@ void squashfs_copy_cache(struct folio *folio,
>   		if (folio_test_uptodate(push_folio))
>   			goto skip_folio;
>   
> -		squashfs_fill_page(&push_folio->page, buffer, offset, avail);
> +		filled = squashfs_fill_page(push_folio, buffer, offset, avail);
>   skip_folio:
> -		folio_unlock(push_folio);
> +		folio_end_read(folio, filled);
>   		if (i != folio->index)
>   			folio_put(push_folio);
>   	}
> diff --git a/fs/squashfs/squashfs.h b/fs/squashfs/squashfs.h
> index 9295556ecfd0..37f3518a804a 100644
> --- a/fs/squashfs/squashfs.h
> +++ b/fs/squashfs/squashfs.h
> @@ -67,7 +67,6 @@ extern __le64 *squashfs_read_fragment_index_table(struct super_block *,
>   				u64, u64, unsigned int);
>   
>   /* file.c */
> -void squashfs_fill_page(struct page *, struct squashfs_cache_entry *, int, int);
>   void squashfs_copy_cache(struct folio *, struct squashfs_cache_entry *,
>   		size_t bytes, size_t offset);
>