linux-ext4 - Re: [PATCH 15/25] ext4: rename 'page' references to 'folio' in multi-block allocator

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Message-ID: <zi2xv42wg45qbveq4vxtdodencx7zb2esscwensoaka2hiojdr@imra4faaz42g>
Date: Wed, 5 Nov 2025 10:21:52 +0100
From: Jan Kara <jack@...e.cz>
To: libaokun@...weicloud.com
Cc: linux-ext4@...r.kernel.org, tytso@....edu, adilger.kernel@...ger.ca, 
	jack@...e.cz, linux-kernel@...r.kernel.org, kernel@...kajraghav.com, 
	mcgrof@...nel.org, linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, 
	yi.zhang@...wei.com, yangerkun@...wei.com, chengzhihao1@...wei.com, 
	libaokun1@...wei.com
Subject: Re: [PATCH 15/25] ext4: rename 'page' references to 'folio' in
 multi-block allocator

On Sat 25-10-25 11:22:11, libaokun@...weicloud.com wrote:
> From: Zhihao Cheng <chengzhihao1@...wei.com>
> 
> The ext4 multi-block allocator now fully supports folio objects. Update
> all variable names, function names, and comments to replace legacy 'page'
> terminology with 'folio', improving clarity and consistency.
> 
> No functional changes.
> 
> Signed-off-by: Zhihao Cheng <chengzhihao1@...wei.com>
> Signed-off-by: Baokun Li <libaokun1@...wei.com>
> Reviewed-by: Zhang Yi <yi.zhang@...wei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/mballoc.c | 22 +++++++++++-----------
>  1 file changed, 11 insertions(+), 11 deletions(-)
> 
> diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
> index 155c43ff2bc2..cf07d1067f5f 100644
> --- a/fs/ext4/mballoc.c
> +++ b/fs/ext4/mballoc.c
> @@ -98,14 +98,14 @@
>   * block bitmap and buddy information. The information are stored in the
>   * inode as:
>   *
> - *  {                        page                        }
> + *  {                        folio                        }
>   *  [ group 0 bitmap][ group 0 buddy] [group 1][ group 1]...
>   *
>   *
>   * one block each for bitmap and buddy information.  So for each group we
> - * take up 2 blocks. A page can contain blocks_per_page (PAGE_SIZE /
> - * blocksize) blocks.  So it can have information regarding groups_per_page
> - * which is blocks_per_page/2
> + * take up 2 blocks. A folio can contain blocks_per_folio (folio_size /
> + * blocksize) blocks.  So it can have information regarding groups_per_folio
> + * which is blocks_per_folio/2
>   *
>   * The buddy cache inode is not stored on disk. The inode is thrown
>   * away when the filesystem is unmounted.
> @@ -1556,7 +1556,7 @@ static int ext4_mb_get_buddy_folio_lock(struct super_block *sb,
>  	return 0;
>  }
>  
> -static void ext4_mb_put_buddy_page_lock(struct ext4_buddy *e4b)
> +static void ext4_mb_put_buddy_folio_lock(struct ext4_buddy *e4b)
>  {
>  	if (e4b->bd_bitmap_folio) {
>  		folio_unlock(e4b->bd_bitmap_folio);
> @@ -1570,7 +1570,7 @@ static void ext4_mb_put_buddy_page_lock(struct ext4_buddy *e4b)
>  
>  /*
>   * Locking note:  This routine calls ext4_mb_init_cache(), which takes the
> - * block group lock of all groups for this page; do not hold the BG lock when
> + * block group lock of all groups for this folio; do not hold the BG lock when
>   * calling this routine!
>   */
>  static noinline_for_stack
> @@ -1618,7 +1618,7 @@ int ext4_mb_init_group(struct super_block *sb, ext4_group_t group, gfp_t gfp)
>  	if (e4b.bd_buddy_folio == NULL) {
>  		/*
>  		 * If both the bitmap and buddy are in
> -		 * the same page we don't need to force
> +		 * the same folio we don't need to force
>  		 * init the buddy
>  		 */
>  		ret = 0;
> @@ -1634,7 +1634,7 @@ int ext4_mb_init_group(struct super_block *sb, ext4_group_t group, gfp_t gfp)
>  		goto err;
>  	}
>  err:
> -	ext4_mb_put_buddy_page_lock(&e4b);
> +	ext4_mb_put_buddy_folio_lock(&e4b);
>  	return ret;
>  }
>  
> @@ -2227,7 +2227,7 @@ static void ext4_mb_use_best_found(struct ext4_allocation_context *ac,
>  	ac->ac_buddy = ret >> 16;
>  
>  	/*
> -	 * take the page reference. We want the page to be pinned
> +	 * take the folio reference. We want the folio to be pinned
>  	 * so that we don't get a ext4_mb_init_cache_call for this
>  	 * group until we update the bitmap. That would mean we
>  	 * double allocate blocks. The reference is dropped
> @@ -2933,7 +2933,7 @@ static int ext4_mb_scan_group(struct ext4_allocation_context *ac,
>  	if (cr < CR_ANY_FREE && spin_is_locked(ext4_group_lock_ptr(sb, group)))
>  		return 0;
>  
> -	/* This now checks without needing the buddy page */
> +	/* This now checks without needing the buddy folio */
>  	ret = ext4_mb_good_group_nolock(ac, group, cr);
>  	if (ret <= 0) {
>  		if (!ac->ac_first_err)
> @@ -4725,7 +4725,7 @@ static void ext4_discard_allocated_blocks(struct ext4_allocation_context *ac)
>  				   "ext4: mb_load_buddy failed (%d)", err))
>  			/*
>  			 * This should never happen since we pin the
> -			 * pages in the ext4_allocation_context so
> +			 * folios in the ext4_allocation_context so
>  			 * ext4_mb_load_buddy() should never fail.
>  			 */
>  			return;
> -- 
> 2.46.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR