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

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Date: Wed, 14 Feb 2024 17:40:26 +0100
From: "Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>
To: "Darrick J. Wong" <djwong@...nel.org>
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

> > @@ -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?

Chinner suggested an alternative to stuff the min_order value in
mp->m_ino_geo. Then it will just be a call to:

mapping_set_folio_orders(VFS_I(ip)->i_mapping,
			M_IGEO(mp)->min_folio_order, MAX_PAGECACHE_ORDER);
> 
> >  	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.
> 
Yes! I will do it as a part of the next revision.