linux-ext4 - Re: [PATCH v2] iomap: iomap that extends beyond EOF should be marked dirty

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Message-ID: <20191017141705.GA31558@infradead.org>
Date:   Thu, 17 Oct 2019 07:17:05 -0700
From:   Christoph Hellwig <hch@...radead.org>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Dave Chinner <david@...morbit.com>, linux-xfs@...r.kernel.org,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Matthew Bobrowski <mbobrowski@...browski.org>
Subject: Re: [PATCH v2] iomap: iomap that extends beyond EOF should be marked
 dirty

On Thu, Oct 17, 2019 at 08:29:11AM -0400, Theodore Y. Ts'o wrote:
> > +	/*
> > +	 * Writes that span EOF might trigger an IO size update on completion,
> > +	 * so consider them to be dirty for the purposes of O_DSYNC even if
> > +	 * there is no other metadata changes being made or are pending here.
> > +	 */
> >  	iomap->flags = 0;
> > -	if (ext4_inode_datasync_dirty(inode))
> > +	if (ext4_inode_datasync_dirty(inode) ||
> > +	    offset + length > i_size_read(inode))
> >  		iomap->flags |= IOMAP_F_DIRTY;
> > +
> >  	iomap->bdev = inode->i_sb->s_bdev;
> >  	iomap->dax_dev = sbi->s_daxdev;
> >  	iomap->offset = (u64)first_block << blkbits;
> 
> Ext4 is not currently using iomap for any kind of writing right now,
> so perhaps this should land via Matthew's patchset?

It does for DAX, which is one of the consumers of IOMAP_F_DIRTY.