linux-ext4 - Re: [PATCH v6 04/11] ext4: move set iomap routines into a separate helper ext4_set

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Message-ID: <20191028235621.GC15221@magnolia>
Date:   Mon, 28 Oct 2019 16:56:21 -0700
From:   "Darrick J. Wong" <darrick.wong@...cle.com>
To:     Matthew Bobrowski <mbobrowski@...browski.org>
Cc:     tytso@....edu, jack@...e.cz, adilger.kernel@...ger.ca,
        linux-ext4@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        hch@...radead.org, david@...morbit.com
Subject: Re: [PATCH v6 04/11] ext4: move set iomap routines into a separate
 helper ext4_set_iomap()

On Tue, Oct 29, 2019 at 07:36:41AM +1100, Matthew Bobrowski wrote:
> On Mon, Oct 28, 2019 at 10:03:48AM -0700, Darrick J. Wong wrote:
> > On Mon, Oct 28, 2019 at 09:51:31PM +1100, Matthew Bobrowski wrote:
> > > +static void ext4_set_iomap(struct inode *inode, struct iomap *iomap,
> > > +			   struct ext4_map_blocks *map, loff_t offset,
> > > +			   loff_t length)
> > > +{
> > > +	u8 blkbits = inode->i_blkbits;
> > > +
> > > +	/*
> > > +	 * Writes that span EOF might trigger an I/O size update on completion,
> > > +	 * so consider them to be dirty for the purpose of O_DSYNC, even if
> > > +	 * there is no other metadata changes being made or are pending.
> > > +	 */
> > > +	iomap->flags = 0;
> > > +	if (ext4_inode_datasync_dirty(inode) ||
> > > +	    offset + length > i_size_read(inode))
> > > +		iomap->flags |= IOMAP_F_DIRTY;
> > > +
> > > +	if (map->m_flags & EXT4_MAP_NEW)
> > > +		iomap->flags |= IOMAP_F_NEW;
> > > +
> > > +	iomap->bdev = inode->i_sb->s_bdev;
> > > +	iomap->dax_dev = EXT4_SB(inode->i_sb)->s_daxdev;
> > > +	iomap->offset = (u64) map->m_lblk << blkbits;
> > > +	iomap->length = (u64) map->m_len << blkbits;
> > > +
> > > +	if (map->m_flags & (EXT4_MAP_MAPPED | EXT4_MAP_UNWRITTEN)) {
> > 
> > /me wonders if this would be easier to follow if it was less indenty:
> > 
> > /*
> >  * <giant comment from below>
> >  */
> > if (m_flags & EXT4_MAP_UNWRITTEN) {
> > 	iomap->type = IOMAP_UNWRITTEN;
> > 	iomap->addr = ...
> > } else if (m_flags & EXT4_MAP_MAPPED) {
> > 	iomap->type = IOAMP_MAPPED;
> > 	iomap->addr = ...
> > } else {
> > 	iomap->type = IOMAP_HOLE;
> > 	iomap->addr = IOMAP_NULL_ADDR;
> > }
> > 
> > Rather than double-checking m_flags?
> 
> Yeah, you're right. The extra checks and levels of indentation aren't really
> necessary and can be simplified further, as you've suggested above.
> 
> Thanks for looking over this for me.
> 
> /me adds this to the TODO for v7.

<nod> I didn't see anything else obviously wrong, FWIW.

--D

> --<M>--