Re: [PATCH 1/2] vfs: move generic_remap_checks out of mm

[Darrick J. Wong]

On Thu, Oct 15, 2020 at 12:38:26PM +0100, Matthew Wilcox wrote:
> On Wed, Oct 14, 2020 at 05:31:21PM -0700, Darrick J. Wong wrote:
> > I would like to move all the generic helpers for the vfs remap range
> > functionality (aka clonerange and dedupe) into a separate file so that
> > they won't be scattered across the vfs and the mm subsystems.  The
> > eventual goal is to be able to deselect remap_range.c if none of the
> > filesystems need that code, but the tricky part here is picking a
> > stable(ish) part of the merge window to rearrange code.
> 
> This makes sense to me.  There's nothing page-cache about this function.
> 
> > diff --git a/mm/filemap.c b/mm/filemap.c
> > index 99c49eeae71b..cf20e5aeb11b 100644
> > --- a/mm/filemap.c
> > +++ b/mm/filemap.c
> > @@ -3098,8 +3098,7 @@ EXPORT_SYMBOL(read_cache_page_gfp);
> >   * LFS limits.  If pos is under the limit it becomes a short access.  If it
> >   * exceeds the limit we return -EFBIG.
> >   */
> > -static int generic_write_check_limits(struct file *file, loff_t pos,
> > -				      loff_t *count)
> > +int generic_write_check_limits(struct file *file, loff_t pos, loff_t *count)
> >  {
> >  	struct inode *inode = file->f_mapping->host;
> >  	loff_t max_size = inode->i_sb->s_maxbytes;
> 
> I wonder if generic_write_check_limits should be in fs/read_write.c --
> it has nothing to do with the pagecache either.

Yeah, probably.

--D