On Thu, Aug 22, 2024 at 07:04:02PM +0100, John Garry wrote:
> On 21/08/2024 18:11, Darrick J. Wong wrote:
> > On Sat, Aug 17, 2024 at 09:48:00AM +0000, John Garry wrote:
> > > For when an inode is enabled for atomic writes, set FMODE_CAN_ATOMIC_WRITE
> > > flag. Only direct IO is currently supported, so check for that also.
> > >
> > > We rely on the block layer to reject atomic writes which exceed the bdev
> > > request_queue limits, so don't bother checking any such thing here.
> > >
> > > Signed-off-by: John Garry <john.g.garry@xxxxxxxxxx>
> > > ---
> > > fs/xfs/xfs_file.c | 14 ++++++++++++++
> > > 1 file changed, 14 insertions(+)
> > >
> > > diff --git a/fs/xfs/xfs_file.c b/fs/xfs/xfs_file.c
> > > index 9b6530a4eb4a..3489d478809e 100644
> > > --- a/fs/xfs/xfs_file.c
> > > +++ b/fs/xfs/xfs_file.c
> > > @@ -1149,6 +1149,18 @@ xfs_file_remap_range(
> > > return remapped > 0 ? remapped : ret;
> > > }
> > > +static bool xfs_file_open_can_atomicwrite(
> > > + struct inode *inode,
> > > + struct file *file)
> > > +{
> > > + struct xfs_inode *ip = XFS_I(inode);
> > > +
> > > + if (!(file->f_flags & O_DIRECT))
> > > + return false;
> > > +
> > > + return xfs_inode_has_atomicwrites(ip);
> >
> > ...and here too. I do like the shift to having an incore flag that
> > controls whether you get untorn write support or not.
>
> Do you mean that add a new member to xfs_inode to record this? If yes, it
> sounds ok, but we need to maintain consistency (of that member) whenever
> anything which can affect it changes, which is always a bit painful.
I actually meant something more like:
static bool
xfs_file_open_can_atomicwrite(
struct file *file,
struct inode *inode)
{
struct xfs_inode *ip = XFS_I(inode);
struct xfs_mount *mp = ip->i_mount;
struct xfs_buftarg *target = xfs_inode_buftarg(ip);
if (!(file->f_flags & O_DIRECT))
return false;
if (!xfs_inode_has_atomicwrites(ip))
return false;
if (mp->m_dalign && (mp->m_dalign % ip->i_extsize))
return false;
if (mp->m_swidth && (mp->m_swidth % ip->i_extsize))
return false;
if (mp->m_sb.sb_blocksize < target->bt_bdev_awu_min)
return false;
if (xfs_inode_alloc_unitsize(ip) > target->bt_bdev_awu_max)
return false;
return true;
}
--D
> John
>
