1 files changed, 379 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_parent.c b/fs/xfs/libxfs/xfs_parent.c
new file mode 100644
index 0000000000..69366c44a7
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_parent.c
@@ -0,0 +1,379 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2022-2024 Oracle.
+ * All rights reserved.
+ */
+#include "xfs.h"
+#include "xfs_fs.h"
+#include "xfs_format.h"
+#include "xfs_da_format.h"
+#include "xfs_log_format.h"
+#include "xfs_shared.h"
+#include "xfs_trans_resv.h"
+#include "xfs_mount.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_inode.h"
+#include "xfs_error.h"
+#include "xfs_trace.h"
+#include "xfs_trans.h"
+#include "xfs_da_btree.h"
+#include "xfs_attr.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_attr_sf.h"
+#include "xfs_bmap.h"
+#include "xfs_defer.h"
+#include "xfs_log.h"
+#include "xfs_xattr.h"
+#include "xfs_parent.h"
+#include "xfs_trans_space.h"
+#include "xfs_attr_item.h"
+#include "xfs_health.h"
+
+struct kmem_cache		*xfs_parent_args_cache;
+
+/*
+ * Parent pointer attribute handling.
+ *
+ * Because the attribute name is a filename component, it will never be longer
+ * than 255 bytes and must not contain nulls or slashes.  These are roughly the
+ * same constraints that apply to attribute names.
+ *
+ * The attribute value must always be a struct xfs_parent_rec.  This means the
+ * attribute will never be in remote format because 12 bytes is nowhere near
+ * xfs_attr_leaf_entsize_local_max() (~75% of block size).
+ *
+ * Creating a new parent attribute will always create a new attribute - there
+ * should never, ever be an existing attribute in the tree for a new inode.
+ * ENOSPC behavior is problematic - creating the inode without the parent
+ * pointer is effectively a corruption, so we allow parent attribute creation
+ * to dip into the reserve block pool to avoid unexpected ENOSPC errors from
+ * occurring.
+ */
+
+/* Return true if parent pointer attr name is valid. */
+bool
+xfs_parent_namecheck(
+	unsigned int			attr_flags,
+	const void			*name,
+	size_t				length)
+{
+	/*
+	 * Parent pointers always use logged operations, so there should never
+	 * be incomplete xattrs.
+	 */
+	if (attr_flags & XFS_ATTR_INCOMPLETE)
+		return false;
+
+	return xfs_dir2_namecheck(name, length);
+}
+
+/* Return true if parent pointer attr value is valid. */
+bool
+xfs_parent_valuecheck(
+	struct xfs_mount		*mp,
+	const void			*value,
+	size_t				valuelen)
+{
+	const struct xfs_parent_rec	*rec = value;
+
+	if (!xfs_has_parent(mp))
+		return false;
+
+	/* The xattr value must be a parent record. */
+	if (valuelen != sizeof(struct xfs_parent_rec))
+		return false;
+
+	/* The parent record must be local. */
+	if (value == NULL)
+		return false;
+
+	/* The parent inumber must be valid. */
+	if (!xfs_verify_dir_ino(mp, be64_to_cpu(rec->p_ino)))
+		return false;
+
+	return true;
+}
+
+/* Compute the attribute name hash for a parent pointer. */
+xfs_dahash_t
+xfs_parent_hashval(
+	struct xfs_mount		*mp,
+	const uint8_t			*name,
+	int				namelen,
+	xfs_ino_t			parent_ino)
+{
+	struct xfs_name			xname = {
+		.name			= name,
+		.len			= namelen,
+	};
+
+	/*
+	 * Use the same dirent name hash as would be used on the directory, but
+	 * mix in the parent inode number to avoid collisions on hardlinked
+	 * files with identical names but different parents.
+	 */
+	return xfs_dir2_hashname(mp, &xname) ^
+		upper_32_bits(parent_ino) ^ lower_32_bits(parent_ino);
+}
+
+/* Compute the attribute name hash from the xattr components. */
+xfs_dahash_t
+xfs_parent_hashattr(
+	struct xfs_mount		*mp,
+	const uint8_t			*name,
+	int				namelen,
+	const void			*value,
+	int				valuelen)
+{
+	const struct xfs_parent_rec	*rec = value;
+
+	/* Requires a local attr value in xfs_parent_rec format */
+	if (valuelen != sizeof(struct xfs_parent_rec)) {
+		ASSERT(valuelen == sizeof(struct xfs_parent_rec));
+		return 0;
+	}
+
+	if (!value) {
+		ASSERT(value != NULL);
+		return 0;
+	}
+
+	return xfs_parent_hashval(mp, name, namelen, be64_to_cpu(rec->p_ino));
+}
+
+/*
+ * Initialize the parent pointer arguments structure.  Caller must have zeroed
+ * the contents of @args.  @tp is only required for updates.
+ */
+static void
+xfs_parent_da_args_init(
+	struct xfs_da_args	*args,
+	struct xfs_trans	*tp,
+	struct xfs_parent_rec	*rec,
+	struct xfs_inode	*child,
+	xfs_ino_t		owner,
+	const struct xfs_name	*parent_name)
+{
+	args->geo = child->i_mount->m_attr_geo;
+	args->whichfork = XFS_ATTR_FORK;
+	args->attr_filter = XFS_ATTR_PARENT;
+	args->op_flags = XFS_DA_OP_LOGGED | XFS_DA_OP_OKNOENT;
+	args->trans = tp;
+	args->dp = child;
+	args->owner = owner;
+	args->name = parent_name->name;
+	args->namelen = parent_name->len;
+	args->value = rec;
+	args->valuelen = sizeof(struct xfs_parent_rec);
+	xfs_attr_sethash(args);
+}
+
+/* Make sure the incore state is ready for a parent pointer query/update. */
+static inline int
+xfs_parent_iread_extents(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*child)
+{
+	/* Parent pointers require that the attr fork must exist. */
+	if (XFS_IS_CORRUPT(child->i_mount, !xfs_inode_has_attr_fork(child))) {
+		xfs_inode_mark_sick(child, XFS_SICK_INO_PARENT);
+		return -EFSCORRUPTED;
+	}
+
+	return xfs_iread_extents(tp, child, XFS_ATTR_FORK);
+}
+
+/* Add a parent pointer to reflect a dirent addition. */
+int
+xfs_parent_addname(
+	struct xfs_trans	*tp,
+	struct xfs_parent_args	*ppargs,
+	struct xfs_inode	*dp,
+	const struct xfs_name	*parent_name,
+	struct xfs_inode	*child)
+{
+	int			error;
+
+	error = xfs_parent_iread_extents(tp, child);
+	if (error)
+		return error;
+
+	xfs_inode_to_parent_rec(&ppargs->rec, dp);
+	xfs_parent_da_args_init(&ppargs->args, tp, &ppargs->rec, child,
+			child->i_ino, parent_name);
+	xfs_attr_defer_add(&ppargs->args, XFS_ATTR_DEFER_SET);
+	return 0;
+}
+
+/* Remove a parent pointer to reflect a dirent removal. */
+int
+xfs_parent_removename(
+	struct xfs_trans	*tp,
+	struct xfs_parent_args	*ppargs,
+	struct xfs_inode	*dp,
+	const struct xfs_name	*parent_name,
+	struct xfs_inode	*child)
+{
+	int			error;
+
+	error = xfs_parent_iread_extents(tp, child);
+	if (error)
+		return error;
+
+	xfs_inode_to_parent_rec(&ppargs->rec, dp);
+	xfs_parent_da_args_init(&ppargs->args, tp, &ppargs->rec, child,
+			child->i_ino, parent_name);
+	xfs_attr_defer_add(&ppargs->args, XFS_ATTR_DEFER_REMOVE);
+	return 0;
+}
+
+/* Replace one parent pointer with another to reflect a rename. */
+int
+xfs_parent_replacename(
+	struct xfs_trans	*tp,
+	struct xfs_parent_args	*ppargs,
+	struct xfs_inode	*old_dp,
+	const struct xfs_name	*old_name,
+	struct xfs_inode	*new_dp,
+	const struct xfs_name	*new_name,
+	struct xfs_inode	*child)
+{
+	int			error;
+
+	error = xfs_parent_iread_extents(tp, child);
+	if (error)
+		return error;
+
+	xfs_inode_to_parent_rec(&ppargs->rec, old_dp);
+	xfs_parent_da_args_init(&ppargs->args, tp, &ppargs->rec, child,
+			child->i_ino, old_name);
+
+	xfs_inode_to_parent_rec(&ppargs->new_rec, new_dp);
+	ppargs->args.new_name = new_name->name;
+	ppargs->args.new_namelen = new_name->len;
+	ppargs->args.new_value = &ppargs->new_rec;
+	ppargs->args.new_valuelen = sizeof(struct xfs_parent_rec);
+	xfs_attr_defer_add(&ppargs->args, XFS_ATTR_DEFER_REPLACE);
+	return 0;
+}
+
+/*
+ * Extract parent pointer information from any parent pointer xattr into
+ * @parent_ino/gen.  The last two parameters can be NULL pointers.
+ *
+ * Returns 0 if this is not a parent pointer xattr at all; or -EFSCORRUPTED for
+ * garbage.
+ */
+int
+xfs_parent_from_attr(
+	struct xfs_mount	*mp,
+	unsigned int		attr_flags,
+	const unsigned char	*name,
+	unsigned int		namelen,
+	const void		*value,
+	unsigned int		valuelen,
+	xfs_ino_t		*parent_ino,
+	uint32_t		*parent_gen)
+{
+	const struct xfs_parent_rec	*rec = value;
+
+	ASSERT(attr_flags & XFS_ATTR_PARENT);
+
+	if (!xfs_parent_namecheck(attr_flags, name, namelen))
+		return -EFSCORRUPTED;
+	if (!xfs_parent_valuecheck(mp, value, valuelen))
+		return -EFSCORRUPTED;
+
+	if (parent_ino)
+		*parent_ino = be64_to_cpu(rec->p_ino);
+	if (parent_gen)
+		*parent_gen = be32_to_cpu(rec->p_gen);
+	return 0;
+}
+
+/*
+ * Look up a parent pointer record (@parent_name -> @pptr) of @ip.
+ *
+ * Caller must hold at least ILOCK_SHARED.  The scratchpad need not be
+ * initialized.
+ *
+ * Returns 0 if the pointer is found, -ENOATTR if there is no match, or a
+ * negative errno.
+ */
+int
+xfs_parent_lookup(
+	struct xfs_trans		*tp,
+	struct xfs_inode		*ip,
+	const struct xfs_name		*parent_name,
+	struct xfs_parent_rec		*pptr,
+	struct xfs_da_args		*scratch)
+{
+	memset(scratch, 0, sizeof(struct xfs_da_args));
+	xfs_parent_da_args_init(scratch, tp, pptr, ip, ip->i_ino, parent_name);
+	return xfs_attr_get_ilocked(scratch);
+}
+
+/* Sanity-check a parent pointer before we try to perform repairs. */
+static inline bool
+xfs_parent_sanity_check(
+	struct xfs_mount		*mp,
+	const struct xfs_name		*parent_name,
+	const struct xfs_parent_rec	*pptr)
+{
+	if (!xfs_parent_namecheck(XFS_ATTR_PARENT, parent_name->name,
+				parent_name->len))
+		return false;
+
+	if (!xfs_parent_valuecheck(mp, pptr, sizeof(*pptr)))
+		return false;
+
+	return true;
+}
+
+
+/*
+ * Attach the parent pointer (@parent_name -> @pptr) to @ip immediately.
+ * Caller must not have a transaction or hold the ILOCK.  This is for
+ * specialized repair functions only.  The scratchpad need not be initialized.
+ */
+int
+xfs_parent_set(
+	struct xfs_inode	*ip,
+	xfs_ino_t		owner,
+	const struct xfs_name	*parent_name,
+	struct xfs_parent_rec	*pptr,
+	struct xfs_da_args	*scratch)
+{
+	if (!xfs_parent_sanity_check(ip->i_mount, parent_name, pptr)) {
+		ASSERT(0);
+		return -EFSCORRUPTED;
+	}
+
+	memset(scratch, 0, sizeof(struct xfs_da_args));
+	xfs_parent_da_args_init(scratch, NULL, pptr, ip, owner, parent_name);
+	return xfs_attr_set(scratch, XFS_ATTRUPDATE_CREATE, false);
+}
+
+/*
+ * Remove the parent pointer (@parent_name -> @pptr) from @ip immediately.
+ * Caller must not have a transaction or hold the ILOCK.  This is for
+ * specialized repair functions only.  The scratchpad need not be initialized.
+ */
+int
+xfs_parent_unset(
+	struct xfs_inode		*ip,
+	xfs_ino_t			owner,
+	const struct xfs_name		*parent_name,
+	struct xfs_parent_rec		*pptr,
+	struct xfs_da_args		*scratch)
+{
+	if (!xfs_parent_sanity_check(ip->i_mount, parent_name, pptr)) {
+		ASSERT(0);
+		return -EFSCORRUPTED;
+	}
+
+	memset(scratch, 0, sizeof(struct xfs_da_args));
+	xfs_parent_da_args_init(scratch, NULL, pptr, ip, owner, parent_name);
+	return xfs_attr_set(scratch, XFS_ATTRUPDATE_REMOVE, false);
+}