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

Darrick J. Wong
2022-08-09T19:07:27Z

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?

> + 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.

> 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;
}

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
>