path: root/fs/xfs/scrub/tempfile.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Copyright (c) 2021-2024 Oracle.  All Rights Reserved.
 * Author: Darrick J. Wong <djwong@kernel.org>
 */
#include "xfs.h"
#include "xfs_fs.h"
#include "xfs_shared.h"
#include "xfs_format.h"
#include "xfs_trans_resv.h"
#include "xfs_mount.h"
#include "xfs_log_format.h"
#include "xfs_trans.h"
#include "xfs_inode.h"
#include "xfs_ialloc.h"
#include "xfs_quota.h"
#include "xfs_bmap.h"
#include "xfs_bmap_btree.h"
#include "xfs_trans_space.h"
#include "xfs_dir2.h"
#include "xfs_exchrange.h"
#include "xfs_exchmaps.h"
#include "xfs_defer.h"
#include "xfs_symlink_remote.h"
#include "xfs_metafile.h"
#include "scrub/scrub.h"
#include "scrub/common.h"
#include "scrub/repair.h"
#include "scrub/trace.h"
#include "scrub/tempfile.h"
#include "scrub/tempexch.h"
#include "scrub/xfile.h"

/*
 * Create a temporary file for reconstructing metadata, with the intention of
 * atomically exchanging the temporary file's contents with the file that's
 * being repaired.
 */
int
xrep_tempfile_create(
	struct xfs_scrub	*sc,
	uint16_t		mode)
{
	struct xfs_icreate_args	args = {
		.pip		= sc->mp->m_rootip,
		.mode		= mode,
		.flags		= XFS_ICREATE_TMPFILE | XFS_ICREATE_UNLINKABLE,
	};
	struct xfs_mount	*mp = sc->mp;
	struct xfs_trans	*tp = NULL;
	struct xfs_dquot	*udqp;
	struct xfs_dquot	*gdqp;
	struct xfs_dquot	*pdqp;
	struct xfs_trans_res	*tres;
	struct xfs_inode	*dp = mp->m_rootip;
	xfs_ino_t		ino;
	unsigned int		resblks;
	bool			is_dir = S_ISDIR(mode);
	int			error;

	if (xfs_is_shutdown(mp))
		return -EIO;
	if (xfs_is_readonly(mp))
		return -EROFS;

	ASSERT(sc->tp == NULL);
	ASSERT(sc->tempip == NULL);

	/*
	 * Make sure that we have allocated dquot(s) on disk.  The temporary
	 * inode should be completely root owned so that we don't fail due to
	 * quota limits.
	 */
	error = xfs_icreate_dqalloc(&args, &udqp, &gdqp, &pdqp);
	if (error)
		return error;

	if (is_dir) {
		resblks = xfs_mkdir_space_res(mp, 0);
		tres = &M_RES(mp)->tr_mkdir;
	} else {
		resblks = XFS_IALLOC_SPACE_RES(mp);
		tres = &M_RES(mp)->tr_create_tmpfile;
	}

	error = xfs_trans_alloc_icreate(mp, tres, udqp, gdqp, pdqp, resblks,
			&tp);
	if (error)
		goto out_release_dquots;

	/* Allocate inode, set up directory. */
	error = xfs_dialloc(&tp, &args, &ino);
	if (error)
		goto out_trans_cancel;
	error = xfs_icreate(tp, ino, &args, &sc->tempip);
	if (error)
		goto out_trans_cancel;

	/* We don't touch file data, so drop the realtime flags. */
	sc->tempip->i_diflags &= ~(XFS_DIFLAG_REALTIME | XFS_DIFLAG_RTINHERIT);
	xfs_trans_log_inode(tp, sc->tempip, XFS_ILOG_CORE);

	/*
	 * Mark our temporary file as private so that LSMs and the ACL code
	 * don't try to add their own metadata or reason about these files.
	 * The file should never be exposed to userspace.
	 */
	VFS_I(sc->tempip)->i_flags |= S_PRIVATE;
	VFS_I(sc->tempip)->i_opflags &= ~IOP_XATTR;

	if (is_dir) {
		error = xfs_dir_init(tp, sc->tempip, dp);
		if (error)
			goto out_trans_cancel;
	} else if (S_ISLNK(VFS_I(sc->tempip)->i_mode)) {
		/*
		 * Initialize the temporary symlink with a meaningless target
		 * that won't trip the verifiers.  Repair must rewrite the
		 * target with meaningful content before swapping with the file
		 * being repaired.  A single-byte target will not write a
		 * remote target block, so the owner is irrelevant.
		 */
		error = xfs_symlink_write_target(tp, sc->tempip,
				sc->tempip->i_ino, ".", 1, 0, 0);
		if (error)
			goto out_trans_cancel;
	}

	/*
	 * Attach the dquot(s) to the inodes and modify them incore.
	 * These ids of the inode couldn't have changed since the new
	 * inode has been locked ever since it was created.
	 */
	xfs_qm_vop_create_dqattach(tp, sc->tempip, udqp, gdqp, pdqp);

	/*
	 * Put our temp file on the unlinked list so it's purged automatically.
	 * All file-based metadata being reconstructed using this file must be
	 * atomically exchanged with the original file because the contents
	 * here will be purged when the inode is dropped or log recovery cleans
	 * out the unlinked list.
	 */
	error = xfs_iunlink(tp, sc->tempip);
	if (error)
		goto out_trans_cancel;

	error = xfs_trans_commit(tp);
	if (error)
		goto out_release_inode;

	trace_xrep_tempfile_create(sc);

	xfs_qm_dqrele(udqp);
	xfs_qm_dqrele(gdqp);
	xfs_qm_dqrele(pdqp);

	/* Finish setting up the incore / vfs context. */
	xfs_iunlock(