Re: [PATCH RESEND v2 13/18] xfs: add parent attributes to link

Alli
2022-08-10T03:09:35Z

On Tue, 2022-08-09 at 11:43 -0700, Darrick J. Wong wrote:
> On Thu, Aug 04, 2022 at 12:40:08PM -0700, Allison Henderson wrote:
> > This patch modifies xfs_link to add a parent pointer to the inode.
> >
> > [bfoster: rebase, use VFS inode fields, fix xfs_bmap_finish()
> > usage]
> > [achender: rebased, changed __unint32_t to xfs_dir2_dataptr_t,
> > fixed null pointer bugs]
> >
> > Signed-off-by: Dave Chinner <dchinner@redhat.com>
> > Signed-off-by: Allison Henderson <allison.henderson@oracle.com>
> > ---
> > fs/xfs/xfs_inode.c | 43 ++++++++++++++++++++++++++++++++++------
> > ---
> > 1 file changed, 34 insertions(+), 9 deletions(-)
> >
> > diff --git a/fs/xfs/xfs_inode.c b/fs/xfs/xfs_inode.c
> > index ef993c3a8963..6e5deb0d42c4 100644
> > --- a/fs/xfs/xfs_inode.c
> > +++ b/fs/xfs/xfs_inode.c
> > @@ -1228,14 +1228,16 @@ xfs_create_tmpfile(
> >
> > int
> > xfs_link(
> > - xfs_inode_t *tdp,
> > - xfs_inode_t *sip,
> > + struct xfs_inode *tdp,
> > + struct xfs_inode *sip,
> > struct xfs_name *target_name)
> > {
> > - xfs_mount_t *mp = tdp->i_mount;
> > - xfs_trans_t *tp;
> > + struct xfs_mount *mp = tdp->i_mount;
> > + struct xfs_trans *tp;
> > int error, nospace_error = 0;
> > int resblks;
> > + xfs_dir2_dataptr_t diroffset;
> > + struct xfs_parent_defer *parent = NULL;
> >
> > trace_xfs_link(tdp, target_name);
> >
> > @@ -1252,11 +1254,17 @@ xfs_link(
> > if (error)
> > goto std_return;
> >
> > + if (xfs_has_parent(mp)) {
> > + error = xfs_parent_init(mp, sip, target_name, &parent);
>
> Why does xfs_parent_init check xfs_has_parent if the callers already
> do
> that?
It was part of the solution outlined in the last review. It is
redundant, but not an inappropriate sanity check for that function
either. I can remove it from the helper if it bothers folks.

>
> > + if (error)
> > + goto std_return;
> > + }
> > +
> > resblks = XFS_LINK_SPACE_RES(mp, target_name->len);
>
> Same comment about increasing XFS_LINK_SPACE_RES to accomodate xattr
> expansion as I had for the last patch.
So we do use XFS_LINK_SPACE_RES here, but didnt we update the tr_link
below in patch 11 to accommodate for the extra space? Maybe I'm not
understanding why we would need both?

>
> > error = xfs_trans_alloc_dir(tdp, &M_RES(mp)->tr_link, sip,
> > &resblks,
> > &tp, &nospace_error);
> > if (error)
> > - goto std_return;
> > + goto drop_incompat;
> >
> > /*
> > * If we are using project inheritance, we only allow hard link
> > @@ -1289,14 +1297,26 @@ xfs_link(
> > }
> >
> > error = xfs_dir_createname(tp, tdp, target_name, sip->i_ino,
> > - resblks, NULL);
> > + resblks, &diroffset);
> > if (error)
> > - goto error_return;
> > + goto out_defer_cancel;
> > xfs_trans_ichgtime(tp, tdp, XFS_ICHGTIME_MOD |
> > XFS_ICHGTIME_CHG);
> > xfs_trans_log_inode(tp, tdp, XFS_ILOG_CORE);
> >
> > xfs_bumplink(tp, sip);
> >
> > + /*
> > + * If we have parent pointers, we now need to add the parent
> > record to
> > + * the attribute fork of the inode. If this is the initial
> > parent
> > + * attribute, we need to create it correctly, otherwise we can
> > just add
> > + * the parent to the inode.
> > + */
> > + if (parent) {
> > + error = xfs_parent_defer_add(tp, tdp, parent,
> > diroffset);
>
> A followup to the comments I made to the previous patch about
> parent->args.dp --
>
> Since you're partially initializing the xfs_defer_parent structure
> before you even have the dir offset, why not delay initializing the
> parent and child pointers until the xfs_parent_defer_add step?
>
> int
> xfs_parent_init(
> struct xfs_mount *mp,
> struct xfs_parent_defer **parentp)
> {
> struct xfs_parent_defer *parent;
> int error;
>
> if (!xfs_has_parent(mp))
> return 0;
>
> error = xfs_attr_grab_log_assist(mp);
> if (error)
> return error;
>
> parent = kzalloc(sizeof(*parent), GFP_KERNEL);
> if (!parent)
> return -ENOMEM;
>
> /* init parent da_args */
> parent->args.geo = mp->m_attr_geo;
> parent->args.whichfork = XFS_ATTR_FORK;
> parent->args.attr_filter = XFS_ATTR_PARENT;
> parent->args.op_flags = XFS_DA_OP_OKNOENT | XFS_DA_OP_LOGGED;
> parent->args.name = (const uint8_t *)&parent->rec;
> parent->args.namelen = sizeof(struct xfs_parent_name_rec);
>
> *parentp = parent;
> return 0;
> }
>
> int
> xfs_parent_defer_add(
> struct xfs_trans *tp,
> struct xfs_parent_defer *parent,
> struct xfs_inode *dp,
> struct xfs_name *parent_name,
> xfs_dir2_dataptr_t parent_offset,
> struct xfs_inode *child)
> {
> struct xfs_da_args *args = &parent->args;
>
> xfs_init_parent_name_rec(&parent->rec, dp, diroffset);
> args->hashval = xfs_da_hashname(args->name, args->namelen);
>
> args->trans = tp;
> args->dp = child;
> if (parent_name) {
> args->name = parent_name->name;
> args->valuelen = parent_name->len;
> }
> return xfs_attr_defer_add(args);
> }
>
> And then the callsites become:
>
> /*
> * If we have parent pointers, we now need to add the parent
> record to
> * the attribute fork of the inode. If this is the initial
> parent
> * attribute, we need to create it correctly, otherwise we can
> just add
> * the parent to the inode.
> */
> if (parent) {
> error = xfs_parent_defer_add(tp, parent, tdp,
> target_name, diroffset, sip);
> if (error)
> goto out_defer_cancel;
> }
Sure, I can scoot that part down to the defer_add helper. Thanks for
the reviews!

Allison
>
> Aside from the API suggestions, the rest looks good to me.
>
> --D
>
> > + if (error)
> > + goto out_defer_cancel;
> > + }
> > +
> > /*
> > * If this is a synchronous mount, make sure that the
> > * link transaction goes to disk before returning to
> > @@ -1310,11 +1330,16 @@ xfs_link(
> > xfs_iunlock(sip, XFS_ILOCK_EXCL);
> > return error;
> >
> > - error_return:
> > +out_defer_cancel:
> > + xfs_defer_cancel(tp);
> > +error_return:
> > xfs_trans_cancel(tp);
> > xfs_iunlock(tdp, XFS_ILOCK_EXCL);
> > xfs_iunlock(sip, XFS_ILOCK_EXCL);
> > - std_return:
> > +drop_incompat:
> > + if (parent)
> > + xfs_parent_cancel(mp, parent);
> > +std_return:
> > if (error == -ENOSPC && nospace_error)
> > error = nospace_error;
> > return error;
> > --
> > 2.25.1
> >