[16/22] xfs: implement live updates for parent pointer repairs

Commit Message

Darrick J. Wong Dec. 31, 2023, 8:57 p.m. UTC

From: Darrick J. Wong <[e-mail]>

While we're scanning the filesystem for dirents that we can turn into
parent pointers, we cannot hold the IOLOCK or ILOCK of the file being
repaired.  Therefore, we need to set up a dirent hook so that we can
keep the temporary file's parent pionters up to date with the rest of
the filesystem.  Hence we add the ability to *remove* pptrs from the
temporary file.

Signed-off-by: Darrick J. Wong <[e-mail]>
---
 fs/xfs/scrub/parent_repair.c |  111 +++++++++++++++++++++++++++++++++++++++---
 fs/xfs/scrub/trace.h         |    2 +
 2 files changed, 106 insertions(+), 7 deletions(-)

Patch

diff --git a/fs/xfs/scrub/parent_repair.c b/fs/xfs/scrub/parent_repair.c
index 8d83aab8caa20..b94eebec3cc79 100644
--- a/fs/xfs/scrub/parent_repair.c
+++ b/fs/xfs/scrub/parent_repair.c
@@ -70,6 +70,12 @@ 
  * disrupt attrmulti cursors.
  */
 
+/* Create a parent pointer in the tempfile. */
+#define XREP_PPTR_ADD		(1)
+
+/* Remove a parent pointer from the tempfile. */
+#define XREP_PPTR_REMOVE	(2)
+
 /* A stashed parent pointer update. */
 struct xrep_pptr {
 	/* Cookie for retrieval of the pptr name. */
@@ -81,6 +87,9 @@  struct xrep_pptr {
 
 	/* Length of the pptr name. */
 	uint8_t				namelen;
+
+	/* XREP_PPTR_{ADD,REMOVE} */
+	uint8_t				action;
 };
 
 /*
@@ -233,13 +242,29 @@  xrep_parent_replay_update(
 	rp->pptr.p_namelen = pptr->namelen;
 	xfs_parent_irec_hashname(sc->mp, &rp->pptr);
 
-	/* Create parent pointer. */
-	trace_xrep_parent_replay_parentadd(sc->tempip, &rp->pptr);
+	switch (pptr->action) {
+	case XREP_PPTR_ADD:
+		/* Create parent pointer. */
+		trace_xrep_parent_replay_parentadd(sc->tempip, &rp->pptr);
 
-	error = xfs_parent_set(sc->tempip, sc->ip->i_ino, &rp->pptr,
-			&rp->pptr_scratch);
-	if (error)
-		return error;
+		error = xfs_parent_set(sc->tempip, sc->ip->i_ino, &rp->pptr,
+				&rp->pptr_scratch);
+		if (error)
+			return error;
+		break;
+	case XREP_PPTR_REMOVE:
+		/* Remove parent pointer. */
+		trace_xrep_parent_replay_parentremove(sc->tempip, &rp->pptr);
+
+		error = xfs_parent_unset(sc->tempip, sc->ip->i_ino, &rp->pptr,
+				&rp->pptr_scratch);
+		if (error)
+			return error;
+		break;
+	default:
+		ASSERT(0);
+		return -EIO;
+	}
 
 	return 0;
 }
@@ -302,6 +327,7 @@  xrep_parent_stash_parentadd(
 	const struct xfs_inode	*dp)
 {
 	struct xrep_pptr	pptr = {
+		.action		= XREP_PPTR_ADD,
 		.namelen	= name->len,
 		.p_ino		= dp->i_ino,
 		.p_gen		= VFS_IC(dp)->i_generation,
@@ -318,6 +344,34 @@  xrep_parent_stash_parentadd(
 	return xfarray_append(rp->pptr_recs, &pptr);
 }
 
+/*
+ * Remember that we want to remove a parent pointer from the tempfile.  These
+ * stashed actions will be replayed later.
+ */
+STATIC int
+xrep_parent_stash_parentremove(
+	struct xrep_parent	*rp,
+	const struct xfs_name	*name,
+	const struct xfs_inode	*dp)
+{
+	struct xrep_pptr	pptr = {
+		.action		= XREP_PPTR_REMOVE,
+		.namelen	= name->len,
+		.p_ino		= dp->i_ino,
+		.p_gen		= VFS_IC(dp)->i_generation,
+	};
+	int			error;
+
+	trace_xrep_parent_stash_parentremove(rp->sc->tempip, dp, name);
+
+	error = xfblob_store(rp->pptr_names, &pptr.name_cookie, name->name,
+			name->len);
+	if (error)
+		return error;
+
+	return xfarray_append(rp->pptr_recs, &pptr);
+}
+
 /*
  * Examine an entry of a directory.  If this dirent leads us back to the file
  * whose parent pointers we're rebuilding, add a pptr to the temporary
@@ -527,6 +581,48 @@  xrep_parent_scan_dirtree(
 	return 0;
 }
 
+/*
+ * Capture dirent updates being made by other threads which are relevant to the
+ * file being repaired.
+ */
+STATIC int
+xrep_parent_live_update(
+	struct notifier_block		*nb,
+	unsigned long			action,
+	void				*data)
+{
+	struct xfs_dir_update_params	*p = data;
+	struct xrep_parent		*rp;
+	struct xfs_scrub		*sc;
+	int				error;
+
+	rp = container_of(nb, struct xrep_parent, pscan.hooks.dirent_hook.nb);
+	sc = rp->sc;
+
+	/*
+	 * This thread updated a dirent that points to the file that we're
+	 * repairing, so stash the update for replay against the temporary
+	 * file.
+	 */
+	if (p->ip->i_ino == sc->ip->i_ino &&
+	    xchk_iscan_want_live_update(&rp->pscan.iscan, p->dp->i_ino)) {
+		mutex_lock(&rp->pscan.lock);
+		if (p->delta > 0)
+			error = xrep_parent_stash_parentadd(rp, p->name, p->dp);
+		else
+			error = xrep_parent_stash_parentremove(rp, p->name,
+					p->dp);
+		mutex_unlock(&rp->pscan.lock);
+		if (error)
+			goto out_abort;
+	}
+
+	return NOTIFY_DONE;
+out_abort:
+	xchk_iscan_abort(&rp->pscan.iscan);
+	return NOTIFY_DONE;
+}
+
 /* Reset a directory's dotdot entry, if needed. */
 STATIC int
 xrep_parent_reset_dotdot(
@@ -698,7 +794,8 @@  xrep_parent_setup_scan(
 	if (error)
 		goto out_recs;
 
-	error = xrep_findparent_scan_start(sc, &rp->pscan);
+	error = __xrep_findparent_scan_start(sc, &rp->pscan,
+			xrep_parent_live_update);
 	if (error)
 		goto out_names;
 
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index def5d72d3c55c..b03e1e69740fa 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -2943,6 +2943,7 @@  DEFINE_EVENT(xrep_pptr_class, name, \
 DEFINE_XREP_PPTR_EVENT(xrep_xattr_replay_parentadd);
 DEFINE_XREP_PPTR_EVENT(xrep_xattr_replay_parentremove);
 DEFINE_XREP_PPTR_EVENT(xrep_parent_replay_parentadd);
+DEFINE_XREP_PPTR_EVENT(xrep_parent_replay_parentremove);
 
 DECLARE_EVENT_CLASS(xrep_pptr_scan_class,
 	TP_PROTO(struct xfs_inode *ip, const struct xfs_inode *dp,
@@ -2978,6 +2979,7 @@  DEFINE_EVENT(xrep_pptr_scan_class, name, \
 		 const struct xfs_name *name), \
 	TP_ARGS(ip, dp, name))
 DEFINE_XREP_PPTR_SCAN_EVENT(xrep_parent_stash_parentadd);
+DEFINE_XREP_PPTR_SCAN_EVENT(xrep_parent_stash_parentremove);
 
 TRACE_EVENT(xrep_nlinks_set_record,
 	TP_PROTO(struct xfs_mount *mp, xfs_ino_t ino,