Re: [PATCH v5 20/24] xfs: disable direct read path for fs-verity files

Andrey Albershteyn
2024-03-12T12:02:58Z

On 2024-03-07 14:11:08, Darrick J. Wong wrote:
> On Mon, Mar 04, 2024 at 08:10:43PM +0100, Andrey Albershteyn wrote:
> > The direct path is not supported on verity files. Attempts to use direct
> > I/O path on such files should fall back to buffered I/O path.
> >
> > Signed-off-by: Andrey Albershteyn <aalbersh@redhat.com>
> > ---
> > fs/xfs/xfs_file.c | 15 ++++++++++++---
> > 1 file changed, 12 insertions(+), 3 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > index 17404c2e7e31..af3201075066 100644
> > --- a/fs/xfs/xfs_file.c
> > +++ b/fs/xfs/xfs_file.c
> > @@ -281,7 +281,8 @@ xfs_file_dax_read(
> > struct kiocb *iocb,
> > struct iov_iter *to)
> > {
> > - struct xfs_inode *ip = XFS_I(iocb->ki_filp->f_mapping->host);
> > + struct inode *inode = iocb->ki_filp->f_mapping->host;
> > + struct xfs_inode *ip = XFS_I(inode);
> > ssize_t ret = 0;
> >
> > trace_xfs_file_dax_read(iocb, to);
> > @@ -334,10 +335,18 @@ xfs_file_read_iter(
> >
> > if (IS_DAX(inode))
> > ret = xfs_file_dax_read(iocb, to);
> > - else if (iocb->ki_flags & IOCB_DIRECT)
> > + else if (iocb->ki_flags & IOCB_DIRECT && !fsverity_active(inode))
> > ret = xfs_file_dio_read(iocb, to);
> > - else
> > + else {
>
> I think the earlier cases need curly braces {} too.
>
> > + /*
> > + * In case fs-verity is enabled, we also fallback to the
> > + * buffered read from the direct read path. Therefore,
> > + * IOCB_DIRECT is set and need to be cleared (see
> > + * generic_file_read_iter())
> > + */
> > + iocb->ki_flags &= ~IOCB_DIRECT;
>
> I'm curious that you added this flag here; how have we gotten along
> this far without clearing it?
>
> --D

Do you know any better place? Not sure if that should be somewhere
before. I've made it same as ext4 does it.

--
- Andrey