Re: [PATCH V6 7/8] fs/xfs: Change xfs_ioctl_setattr_dax_invalidate() to xfs_ioctl_dax_check()

Ira Weiny
2020-04-08T18:13:09Z

On Wed, Apr 08, 2020 at 08:37:17AM -0700, Darrick J. Wong wrote:
> On Tue, Apr 07, 2020 at 11:29:57AM -0700, ira.weiny@intel.com wrote:
> > From: Ira Weiny <ira.weiny@intel.com>
> >
> > We only support changing FS_XFLAG_DAX on directories. Files get their
> > flag from the parent directory on creation only. So no data
> > invalidation needs to happen.
> >
> > Alter the xfs_ioctl_setattr_dax_invalidate() to be
> > xfs_ioctl_dax_check().
> >
> > This also allows use to remove the join_flags logic.
> >
> > Signed-off-by: Ira Weiny <ira.weiny@intel.com>
> >
> > ---
> > Changes from v5:
> > New patch
> > ---
> > fs/xfs/xfs_ioctl.c | 91 +++++-----------------------------------------
> > 1 file changed, 10 insertions(+), 81 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
> > index c6cd92ef4a05..5472faab7c4f 100644
> > --- a/fs/xfs/xfs_ioctl.c
> > +++ b/fs/xfs/xfs_ioctl.c
> > @@ -1145,63 +1145,18 @@ xfs_ioctl_setattr_xflags(
> > }
> >
> > /*
> > - * If we are changing DAX flags, we have to ensure the file is clean and any
> > - * cached objects in the address space are invalidated and removed. This
> > - * requires us to lock out other IO and page faults similar to a truncate
> > - * operation. The locks need to be held until the transaction has been committed
> > - * so that the cache invalidation is atomic with respect to the DAX flag
> > - * manipulation.
> > + * Only directories are allowed to change dax flags
> > */
> > static int
> > xfs_ioctl_setattr_dax_invalidate(
> > - struct xfs_inode *ip,
> > - struct fsxattr *fa,
> > - int *join_flags)
> > + struct xfs_inode *ip)
> > {
> > struct inode *inode = VFS_I(ip);
> > - struct super_block *sb = inode->i_sb;
> > - int error;
> > -
> > - *join_flags = 0;
> > -
> > - /*
> > - * It is only valid to set the DAX flag on regular files and
> > - * directories on filesystems where the block size is equal to the page
> > - * size. On directories it serves as an inherited hint so we don't
> > - * have to check the device for dax support or flush pagecache.
> > - */
> > - if (fa->fsx_xflags & FS_XFLAG_DAX) {
> > - struct xfs_buftarg *target = xfs_inode_buftarg(ip);
> > -
> > - if (!bdev_dax_supported(target->bt_bdev, sb->s_blocksize))
> > - return -EINVAL;
> > - }
> > -
> > - /* If the DAX state is not changing, we have nothing to do here. */
> > - if ((fa->fsx_xflags & FS_XFLAG_DAX) && IS_DAX(inode))
> > - return 0;
> > - if (!(fa->fsx_xflags & FS_XFLAG_DAX) && !IS_DAX(inode))
> > - return 0;
>
> Does the !S_ISDIR check below apply unconditionally even if we weren't
> trying to change the DAX flag?

:-/

shoot... I really screwed this up...

>
> > - if (S_ISDIR(inode->i_mode))
> > - return 0;
> >
> > - /* lock, flush and invalidate mapping in preparation for flag change */
> > - xfs_ilock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL);
> > - error = filemap_write_and_wait(inode->i_mapping);
> > - if (error)
> > - goto out_unlock;
> > - error = invalidate_inode_pages2(inode->i_mapping);
> > - if (error)
> > - goto out_unlock;
> > + if (!S_ISDIR(inode->i_mode))
> > + return -EINVAL;
>
> If this entire function collapses to an S_ISDIR check then you might
> as well just hoist this one piece to the caller.

Oops... yea this is broken... All broken.

> Also, where is
> xfs_ioctl_dax_check?

I forgot to change the name.

>
> <confused>

Much less so than me... :-/

I'll clean it up.

Thanks, this was really bad on my part...
Ira

>
> --D
>
> >
> > - *join_flags = XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL;
> > return 0;
> > -
> > -out_unlock:
> > - xfs_iunlock(ip, XFS_MMAPLOCK_EXCL | XFS_IOLOCK_EXCL);
> > - return error;
> > -
> > }
> >
> > /*
> > @@ -1209,17 +1164,10 @@ xfs_ioctl_setattr_dax_invalidate(
> > * have permission to do so. On success, return a clean transaction and the
> > * inode locked exclusively ready for further operation specific checks. On
> > * failure, return an error without modifying or locking the inode.
> > - *
> > - * The inode might already be IO locked on call. If this is the case, it is
> > - * indicated in @join_flags and we take full responsibility for ensuring they
> > - * are unlocked from now on. Hence if we have an error here, we still have to
> > - * unlock them. Otherwise, once they are joined to the transaction, they will
> > - * be unlocked on commit/cancel.
> > */
> > static struct xfs_trans *
> > xfs_ioctl_setattr_get_trans(
> > - struct xfs_inode *ip,
> > - int join_flags)
> > + struct xfs_inode *ip)
> > {
> > struct xfs_mount *mp = ip->i_mount;
> > struct xfs_trans *tp;
> > @@ -1236,8 +1184,7 @@ xfs_ioctl_setattr_get_trans(
> > goto out_unlock;
> >
> > xfs_ilock(ip, XFS_ILOCK_EXCL);
> > - xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL | join_flags);
> > - join_flags = 0;
> > + xfs_trans_ijoin(tp, ip, XFS_ILOCK_EXCL);
> >
> > /*
> > * CAP_FOWNER overrides the following restrictions:
> > @@ -1258,8 +1205,6 @@ xfs_ioctl_setattr_get_trans(
> > out_cancel:
> > xfs_trans_cancel(tp);
> > out_unlock:
> > - if (join_flags)
> > - xfs_iunlock(ip, join_flags);
> > return ERR_PTR(error);
> > }
> >
> > @@ -1386,7 +1331,6 @@ xfs_ioctl_setattr(
> > struct xfs_dquot *pdqp = NULL;
> > struct xfs_dquot *olddquot = NULL;
> > int code;
> > - int join_flags = 0;
> >
> > trace_xfs_ioctl_setattr(ip);
> >
> > @@ -1410,18 +1354,11 @@ xfs_ioctl_setattr(
> > return code;
> > }
> >
> > - /*
> > - * Changing DAX config may require inode locking for mapping
> > - * invalidation. These need to be held all the way to transaction commit
> > - * or cancel time, so need to be passed through to
> > - * xfs_ioctl_setattr_get_trans() so it can apply them to the join call
> > - * appropriately.
> > - */
> > - code = xfs_ioctl_setattr_dax_invalidate(ip, fa, &join_flags);
> > + code = xfs_ioctl_setattr_dax_invalidate(ip);
> > if (code)
> > goto error_free_dquots;
> >
> > - tp = xfs_ioctl_setattr_get_trans(ip, join_flags);
> > + tp = xfs_ioctl_setattr_get_trans(ip);
> > if (IS_ERR(tp)) {
> > code = PTR_ERR(tp);
> > goto error_free_dquots;
> > @@ -1552,7 +1489,6 @@ xfs_ioc_setxflags(
> > struct fsxattr fa;
> > struct fsxattr old_fa;
> > unsigned int flags;
> > - int join_flags = 0;
> > int error;
> >
> > if (copy_from_user(&flags, arg, sizeof(flags)))
> > @@ -1569,18 +1505,11 @@ xfs_ioc_setxflags(
> > if (error)
> > return error;
> >
> > - /*
> > - * Changing DAX config may require inode locking for mapping
> > - * invalidation. These need to be held all the way to transaction commit
> > - * or cancel time, so need to be passed through to
> > - * xfs_ioctl_setattr_get_trans() so it can apply them to the join call
> > - * appropriately.
> > - */
> > - error = xfs_ioctl_setattr_dax_invalidate(ip, &fa, &join_flags);
> > + error = xfs_ioctl_setattr_dax_invalidate(ip);
> > if (error)
> > goto out_drop_write;
> >
> > - tp = xfs_ioctl_setattr_get_trans(ip, join_flags);
> > + tp = xfs_ioctl_setattr_get_trans(ip);
> > if (IS_ERR(tp)) {
> > error = PTR_ERR(tp);
> > goto out_drop_write;
> > --
> > 2.25.1
> >