linux-kernel - Re: [RFC v2 14/14] xfs: enable block size larger than page size support

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Message-ID: <20240213162007.GO6184@frogsfrogsfrogs>
Date: Tue, 13 Feb 2024 08:20:07 -0800
From: "Darrick J. Wong" <djwong@...nel.org>
To: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
Cc: linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	mcgrof@...nel.org, gost.dev@...sung.com, akpm@...ux-foundation.org,
	kbusch@...nel.org, chandan.babu@...cle.com, p.raghav@...sung.com,
	linux-kernel@...r.kernel.org, hare@...e.de, willy@...radead.org,
	linux-mm@...ck.org, david@...morbit.com
Subject: Re: [RFC v2 14/14] xfs: enable block size larger than page size
 support

On Tue, Feb 13, 2024 at 10:37:13AM +0100, Pankaj Raghav (Samsung) wrote:
> From: Pankaj Raghav <p.raghav@...sung.com>
> 
> Page cache now has the ability to have a minimum order when allocating
> a folio which is a prerequisite to add support for block size > page
> size. Enable it in XFS under CONFIG_XFS_LBS.
> 
> Signed-off-by: Luis Chamberlain <mcgrof@...nel.org>
> Signed-off-by: Pankaj Raghav <p.raghav@...sung.com>
> ---
>  fs/xfs/xfs_icache.c | 8 ++++++--
>  fs/xfs/xfs_super.c  | 8 +++-----
>  2 files changed, 9 insertions(+), 7 deletions(-)
> 
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index dba514a2c84d..9de81caf7ad4 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -73,6 +73,7 @@ xfs_inode_alloc(
>  	xfs_ino_t		ino)
>  {
>  	struct xfs_inode	*ip;
> +	int			min_order = 0;
>  
>  	/*
>  	 * XXX: If this didn't occur in transactions, we could drop GFP_NOFAIL
> @@ -88,7 +89,8 @@ xfs_inode_alloc(
>  	/* VFS doesn't initialise i_mode or i_state! */
>  	VFS_I(ip)->i_mode = 0;
>  	VFS_I(ip)->i_state = 0;
> -	mapping_set_large_folios(VFS_I(ip)->i_mapping);
> +	min_order = max(min_order, ilog2(mp->m_sb.sb_blocksize) - PAGE_SHIFT);
> +	mapping_set_folio_orders(VFS_I(ip)->i_mapping, min_order, MAX_PAGECACHE_ORDER);
>  
>  	XFS_STATS_INC(mp, vn_active);
>  	ASSERT(atomic_read(&ip->i_pincount) == 0);
> @@ -313,6 +315,7 @@ xfs_reinit_inode(
>  	dev_t			dev = inode->i_rdev;
>  	kuid_t			uid = inode->i_uid;
>  	kgid_t			gid = inode->i_gid;
> +	int			min_order = 0;
>  
>  	error = inode_init_always(mp->m_super, inode);
>  
> @@ -323,7 +326,8 @@ xfs_reinit_inode(
>  	inode->i_rdev = dev;
>  	inode->i_uid = uid;
>  	inode->i_gid = gid;
> -	mapping_set_large_folios(inode->i_mapping);
> +	min_order = max(min_order, ilog2(mp->m_sb.sb_blocksize) - PAGE_SHIFT);
> +	mapping_set_folio_orders(inode->i_mapping, min_order, MAX_PAGECACHE_ORDER);

Twice now I've seen this, which makes me think "refactor this into a
single function."

But then, this is really just:

	mapping_set_folio_orders(inode->i_mapping,
			max(0, inode->i_sb->s_blocksize_bits - PAGE_SHIFT),
			MAX_PAGECACHE_ORDER);

Can we make that a generic inode_set_pagecache_orders helper?

>  	return error;
>  }
>  
> diff --git a/fs/xfs/xfs_super.c b/fs/xfs/xfs_super.c
> index 5a2512d20bd0..6a3f0f6727eb 100644
> --- a/fs/xfs/xfs_super.c
> +++ b/fs/xfs/xfs_super.c
> @@ -1625,13 +1625,11 @@ xfs_fs_fill_super(
>  		goto out_free_sb;
>  	}
>  
> -	/*
> -	 * Until this is fixed only page-sized or smaller data blocks work.
> -	 */
> -	if (mp->m_sb.sb_blocksize > PAGE_SIZE) {
> +	if (!IS_ENABLED(CONFIG_XFS_LBS) && mp->m_sb.sb_blocksize > PAGE_SIZE) {
>  		xfs_warn(mp,
>  		"File system with blocksize %d bytes. "
> -		"Only pagesize (%ld) or less will currently work.",
> +		"Only pagesize (%ld) or less will currently work. "
> +		"Enable Experimental CONFIG_XFS_LBS for this support",
>  				mp->m_sb.sb_blocksize, PAGE_SIZE);

Please log a warning about the EXPERIMENTAL bs>ps feature being used
on this mount for the CONFIG_XFS_LBS=y case.

--D

>  		error = -ENOSYS;
>  		goto out_free_sb;
> -- 
> 2.43.0
> 
>