Re: [PATCH v2 16/16] xfs: add pre-content fsnotify hook for write faults

[Josef Bacik <josef@toxicpanda.com>]

On Fri, Aug 09, 2024 at 08:03:41AM +1000, Dave Chinner wrote:
> On Thu, Aug 08, 2024 at 03:27:18PM -0400, Josef Bacik wrote:
> > xfs has it's own handling for write faults, so we need to add the
> > pre-content fsnotify hook for this case.  Reads go through filemap_fault
> > so they're handled properly there.
> > 
> > Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> > ---
> >  fs/xfs/xfs_file.c | 20 +++++++++++++++++---
> >  1 file changed, 17 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > index 4cdc54dc9686..585a8c2eea0f 100644
> > --- a/fs/xfs/xfs_file.c
> > +++ b/fs/xfs/xfs_file.c
> > @@ -1325,14 +1325,28 @@ __xfs_filemap_fault(
> >  	bool			write_fault)
> >  {
> >  	struct inode		*inode = file_inode(vmf->vma->vm_file);
> > +	struct file		*fpin = NULL;
> > +	vm_fault_t		ret;
> >  
> >  	trace_xfs_filemap_fault(XFS_I(inode), order, write_fault);
> >  
> > -	if (write_fault)
> > -		return xfs_write_fault(vmf, order);
> >  	if (IS_DAX(inode))
> >  		return xfs_dax_read_fault(vmf, order);
> > -	return filemap_fault(vmf);
> > +
> > +	if (!write_fault)
> > +		return filemap_fault(vmf);
> 
> Doesn't this break DAX read faults? i.e. they have to go through
> xfs_dax_read_fault(), not filemap_fault().

Oops my bad, I had it right before then decided to make it cleaner and forgot
what the original code was doing, I'll fix it up, thanks!

Josef