xfs: ensure dentry consistency when the orphanage adopts a filerepair-orphanage_2022-10-14

When the orphanage adopts a file, that file becomes a child of the
orphanage.  The dentry cache may have entries for the orphanage
directory and the name we've chosen, so (1) make sure we abort if the
dcache has a positive entry because something's not right; and (2)
invalidate and purge negative dentries if the adoption goes through.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>

2 files changed, 127 insertions, 5 deletions

diff --git a/fs/xfs/scrub/orphanage.c b/fs/xfs/scrub/orphanage.c
index 1fe7935433bf..08ff273dbb39 100644
--- a/fs/xfs/scrub/orphanage.c
+++ b/fs/xfs/scrub/orphanage.c
@@ -357,6 +357,89 @@ xrep_orphanage_adoption_prep(
 }
 
 /*
+ * Make sure the dcache does not have a positive dentry for the name we've
+ * chosen.  The caller should have checked with the ondisk directory, so any
+ * discrepancy is a sign that something is seriously wrong.
+ */
+static int
+xrep_orphanage_check_dcache(
+	struct xrep_orphanage_req	*orph)
+{
+	struct qstr			qname = QSTR_INIT(orph->xname.name,
+							  orph->xname.len);
+	struct dentry			*d_orphanage, *d_child, *dentry;
+	int				error = 0;
+
+	d_orphanage = d_find_alias(VFS_I(orph->sc->orphanage));
+	if (!d_orphanage)
+		return 0;
+
+	d_child = d_hash_and_lookup(d_orphanage, &qname);
+	if (d_child) {
+		trace_xrep_orphanage_check_child(orph->sc->mp, d_child);
+
+		if (d_is_positive(d_child)) {
+			ASSERT(d_is_negative(d_child));
+			error = -EFSCORRUPTED;
+		}
+
+		dput(d_child);
+	}
+
+	dput(d_orphanage);
+	if (error)
+		return error;
+
+	/*
+	 * Do we need to update d_parent of the dentry for the file being
+	 * repaired?  In theory there shouldn't be one since the file had
+	 * nonzero nlink but wasn't connected to any parent dir.
+	 */
+	dentry = d_find_alias(VFS_I(orph->sc->ip));
+	if (dentry) {
+		trace_xrep_orphanage_check_dentry(orph->sc->mp, d_child);
+		ASSERT(dentry->d_parent == NULL);
+
+		dput(dentry);
+		return -EFSCORRUPTED;
+	}
+
+	return 0;
+}
+
+/*
+ * Remove all negative dentries from the dcache.  There should not be any
+ * positive entries, since we've maintained our lock on the orphanage
+ * directory.
+ */
+static int
+xrep_orphanage_zap_dcache(
+	struct xrep_orphanage_req	*orph)
+{
+	struct qstr			qname = QSTR_INIT(orph->xname.name,
+							  orph->xname.len);
+	struct dentry			*d_orphanage, *d_child;
+	int				error = 0;
+
+	d_orphanage = d_find_alias(VFS_I(orph->sc->orphanage));
+	if (!d_orphanage)
+		return 0;
+
+	d_child = d_hash_and_lookup(d_orphanage, &qname);
+	while (d_child != NULL) {
+		trace_xrep_orphanage_zap_child(orph->sc->mp, d_child);
+
+		ASSERT(d_is_negative(d_child));
+		d_invalidate(d_child);
+		dput(d_child);
+		d_child = d_lookup(d_orphanage, &qname);
+	}
+
+	dput(d_orphanage);
+	return error;
+}
+
+/*
  * Move the current file to the orphanage.
  *
  * The caller must hold the IOLOCKs and the ILOCKs for both sc->ip and the
@@ -375,6 +458,10 @@ xrep_orphanage_adopt(
 
 	trace_xrep_orphanage_adopt(sc->orphanage, &orph->xname, sc->ip->i_ino);
 
+	error = xrep_orphanage_check_dcache(orph);
+	if (error)
+		return error;
+
 	/*
 	 * Create the new name in the orphanage, and bump the link count of
 	 * the orphanage if we just added a directory.
@@ -390,12 +477,15 @@ xrep_orphanage_adopt(
 		xfs_bumplink(sc->tp, sc->orphanage);
 	xfs_trans_log_inode(sc->tp, sc->orphanage, XFS_ILOG_CORE);
 
-	if (!isdir)
-		return 0;
+	if (isdir) {
+		/* Replace the dotdot entry in the child directory. */
+		error = xfs_dir_replace(sc->tp, sc->ip, &xfs_name_dotdot,
+				sc->orphanage->i_ino, orph->child_blkres);
+		if (error)
+			return error;
+	}
 
-	/* Replace the dotdot entry in the child directory. */
-	return xfs_dir_replace(sc->tp, sc->ip, &xfs_name_dotdot,
-			sc->orphanage->i_ino, orph->child_blkres);
+	return xrep_orphanage_zap_dcache(orph);
 }
 
 /* Release the orphanage. */
diff --git a/fs/xfs/scrub/trace.h b/fs/xfs/scrub/trace.h
index 8d5067b4e3d9..f86a287a3158 100644
--- a/fs/xfs/scrub/trace.h
+++ b/fs/xfs/scrub/trace.h
@@ -2534,6 +2534,38 @@ TRACE_EVENT(xrep_nlinks_set_record,
 		  __entry->children)
 );
 
+DECLARE_EVENT_CLASS(xrep_dentry_class,
+	TP_PROTO(struct xfs_mount *mp, const struct dentry *dentry),
+	TP_ARGS(mp, dentry),
+	TP_STRUCT__entry(
+		__field(dev_t, dev)
+		__field(unsigned int, type)
+		__field(unsigned long, ino)
+		__field(bool, positive)
+		__field(bool, has_parent)
+	),
+	TP_fast_assign(
+		__entry->dev = mp->m_super->s_dev;
+		__entry->type = __d_entry_type(dentry);
+		__entry->positive = d_is_positive(dentry);
+		__entry->has_parent = dentry->d_parent != NULL;
+		__entry->ino = d_inode(dentry) ? d_inode(dentry)->i_ino : 0;
+	),
+	TP_printk("dev %d:%d type 0x%x positive? %d parent? %d ino 0x%lx",
+		  MAJOR(__entry->dev), MINOR(__entry->dev),
+		  __entry->type,
+		  __entry->positive,
+		  __entry->has_parent,
+		  __entry->ino)
+);
+#define DEFINE_REPAIR_DENTRY_EVENT(name) \
+DEFINE_EVENT(xrep_dentry_class, name, \
+	TP_PROTO(struct xfs_mount *mp, const struct dentry *dentry), \
+	TP_ARGS(mp, dentry))
+DEFINE_REPAIR_DENTRY_EVENT(xrep_orphanage_check_child);
+DEFINE_REPAIR_DENTRY_EVENT(xrep_orphanage_check_dentry);
+DEFINE_REPAIR_DENTRY_EVENT(xrep_orphanage_zap_child);
+
 #endif /* IS_ENABLED(CONFIG_XFS_ONLINE_REPAIR) */