Re: [PATCH 9/9] xfs: Get rid of ->bmap

From: Carlos Maiolino <cmaiolino@redhat.com>
To: "Darrick J. Wong" <darrick.wong@oracle.com>
Cc: linux-fsdevel@vger.kernel.org, hch@lst.de, adilger@dilger.ca,
	linux-xfs@vger.kernel.org
Subject: Re: [PATCH 9/9] xfs: Get rid of ->bmap
Date: Wed, 18 Sep 2019 10:13:04 +0200	[thread overview]
Message-ID: <20190918081303.zwnxr7pvtotr7cnt@pegasus.maiolino.io> (raw)
In-Reply-To: <20190916175049.GD2229799@magnolia>

On Mon, Sep 16, 2019 at 10:50:49AM -0700, Darrick J. Wong wrote:
> On Wed, Sep 11, 2019 at 03:43:15PM +0200, Carlos Maiolino wrote:
> > We don't need ->bmap anymore, only usage for it was FIBMAP, which is now
> > gone.
> > 
> > Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>
> > ---
> > 
> > Changelog:
> > 	V5:
> > 		- Properly rebase against 5.3
> > 		- iomap_{bmap(),bmap_actor()} are now used also by GFS2, so
> > 		  don't remove them anymore
> > 	V2:
> > 		- Kill iomap_bmap() and iomap_bmap_actor()
> > 
> >  fs/xfs/xfs_aops.c  | 24 ------------------------
> >  fs/xfs/xfs_trace.h |  1 -
> >  2 files changed, 25 deletions(-)
> > 
> > diff --git a/fs/xfs/xfs_aops.c b/fs/xfs/xfs_aops.c
> > index 4e4a4d7df5ac..a2884537d2c2 100644
> > --- a/fs/xfs/xfs_aops.c
> > +++ b/fs/xfs/xfs_aops.c
> > @@ -1138,29 +1138,6 @@ xfs_vm_releasepage(
> >  	return iomap_releasepage(page, gfp_mask);
> >  }
> >  
> > -STATIC sector_t
> > -xfs_vm_bmap(
> > -	struct address_space	*mapping,
> > -	sector_t		block)
> > -{
> > -	struct xfs_inode	*ip = XFS_I(mapping->host);
> > -
> > -	trace_xfs_vm_bmap(ip);
> > -
> > -	/*
> > -	 * The swap code (ab-)uses ->bmap to get a block mapping and then
> > -	 * bypasses the file system for actual I/O.  We really can't allow
> > -	 * that on reflinks inodes, so we have to skip out here.  And yes,
> > -	 * 0 is the magic code for a bmap error.
> > -	 *
> > -	 * Since we don't pass back blockdev info, we can't return bmap
> > -	 * information for rt files either.
> > -	 */
> > -	if (xfs_is_cow_inode(ip) || XFS_IS_REALTIME_INODE(ip))
> 
> Uhhhh where does this check happen now?

All checks are now made in the caller, bmap_fiemap() based on the filesystem's
returned flags in the fiemap structure. So, it will decide to pass the result
back, or just return -EINVAL.

Well, there is no way for iomap (or bmap_fiemap now) detect the block is in a
realtime device, since we have no flags for that.

Following Christoph's line of thought here, maybe we can add a new IOMAP_F_* so
the filesystem can notify iomap the extent is in a different device? I don't
know, just a thought.

This would still keep the consistency of leaving bmap_fiemap() with the decision
of passing or not.

Cheers.

> 
> --D
> 
> > -		return 0;
> > -	return iomap_bmap(mapping, block, &xfs_iomap_ops);
> > -}
> > -
> >  STATIC int
> >  xfs_vm_readpage(
> >  	struct file		*unused,
> > @@ -1199,7 +1176,6 @@ const struct address_space_operations xfs_address_space_operations = {
> >  	.set_page_dirty		= iomap_set_page_dirty,
> >  	.releasepage		= xfs_vm_releasepage,
> >  	.invalidatepage		= xfs_vm_invalidatepage,
> > -	.bmap			= xfs_vm_bmap,
> >  	.direct_IO		= noop_direct_IO,
> >  	.migratepage		= iomap_migrate_page,
> >  	.is_partially_uptodate  = iomap_is_partially_uptodate,
> > diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> > index eaae275ed430..c226b562f5da 100644
> > --- a/fs/xfs/xfs_trace.h
> > +++ b/fs/xfs/xfs_trace.h
> > @@ -626,7 +626,6 @@ DEFINE_INODE_EVENT(xfs_readdir);
> >  #ifdef CONFIG_XFS_POSIX_ACL
> >  DEFINE_INODE_EVENT(xfs_get_acl);
> >  #endif
> > -DEFINE_INODE_EVENT(xfs_vm_bmap);
> >  DEFINE_INODE_EVENT(xfs_file_ioctl);
> >  DEFINE_INODE_EVENT(xfs_file_compat_ioctl);
> >  DEFINE_INODE_EVENT(xfs_ioctl_setattr);
> > -- 
> > 2.20.1
> > 

-- 
Carlos