1 files changed, 485 insertions, 0 deletions
diff --git a/fs/xfs/libxfs/xfs_metadir.c b/fs/xfs/libxfs/xfs_metadir.c
new file mode 100644
index 000000000000..178e89711cb7
--- /dev/null
+++ b/fs/xfs/libxfs/xfs_metadir.c
@@ -0,0 +1,485 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2018-2024 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_log_format.h"
+#include "xfs_trans_resv.h"
+#include "xfs_bit.h"
+#include "xfs_sb.h"
+#include "xfs_mount.h"
+#include "xfs_defer.h"
+#include "xfs_trans.h"
+#include "xfs_metafile.h"
+#include "xfs_metadir.h"
+#include "xfs_trace.h"
+#include "xfs_inode.h"
+#include "xfs_quota.h"
+#include "xfs_ialloc.h"
+#include "xfs_bmap_btree.h"
+#include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_trans_space.h"
+#include "xfs_ag.h"
+#include "xfs_dir2.h"
+#include "xfs_dir2_priv.h"
+#include "xfs_parent.h"
+#include "xfs_health.h"
+#include "xfs_errortag.h"
+#include "xfs_error.h"
+#include "xfs_btree.h"
+#include "xfs_alloc.h"
+
+/*
+ * Metadata Directory Tree
+ * =======================
+ *
+ * These functions provide an abstraction layer for looking up, creating, and
+ * deleting metadata inodes that live within a special metadata directory tree.
+ *
+ * This code does not manage the five existing metadata inodes: real time
+ * bitmap & summary; and the user, group, and quotas.  All other metadata
+ * inodes must use only the xfs_meta{dir,file}_* functions.
+ *
+ * Callers wishing to create or hardlink a metadata inode must create an
+ * xfs_metadir_update structure, call the appropriate xfs_metadir* function,
+ * and then call xfs_metadir_commit or xfs_metadir_cancel to commit or cancel
+ * the update.  Files in the metadata directory tree currently cannot be
+ * unlinked.
+ *
+ * When the metadir feature is enabled, all metadata inodes must have the
+ * "metadata" inode flag set to prevent them from being exposed to the outside
+ * world.
+ *
+ * Callers must take the ILOCK of any inode in the metadata directory tree to
+ * synchronize access to that inode.  It is never necessary to take the IOLOCK
+ * or the MMAPLOCK since metadata inodes must not be exposed to user space.
+ */
+
+static inline void
+xfs_metadir_set_xname(
+	struct xfs_name		*xname,
+	const char		*path,
+	unsigned char		ftype)
+{
+	xname->name = (const unsigned char *)path;
+	xname->len = strlen(path);
+	xname->type = ftype;
+}
+
+/*
+ * Given a parent directory @dp and a metadata inode path component @xname,
+ * Look up the inode number in the directory, returning it in @ino.
+ * @xname.type must match the directory entry's ftype.
+ *
+ * Caller must hold ILOCK_EXCL.
+ */
+static inline int
+xfs_metadir_lookup(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	struct xfs_name		*xname,
+	xfs_ino_t		*ino)
+{
+	struct xfs_mount	*mp = dp->i_mount;
+	struct xfs_da_args	args = {
+		.trans		= tp,
+		.dp		= dp,
+		.geo		= mp->m_dir_geo,
+		.name		= xname->name,
+		.namelen	= xname->len,
+		.hashval	= xfs_dir2_hashname(mp, xname),
+		.whichfork	= XFS_DATA_FORK,
+		.op_flags	= XFS_DA_OP_OKNOENT,
+		.owner		= dp->i_ino,
+	};
+	int			error;
+
+	if (!S_ISDIR(VFS_I(dp)->i_mode)) {
+		xfs_fs_mark_sick(mp, XFS_SICK_FS_METADIR);
+		return -EFSCORRUPTED;
+	}
+	if (xfs_is_shutdown(mp))
+		return -EIO;
+
+	error = xfs_dir_lookup_args(&args);
+	if (error)
+		return error;
+
+	if (!xfs_verify_ino(mp, args.inumber)) {
+		xfs_fs_mark_sick(mp, XFS_SICK_FS_METADIR);
+		return -EFSCORRUPTED;
+	}
+	if (xname->type != XFS_DIR3_FT_UNKNOWN && xname->type != args.filetype) {
+		xfs_fs_mark_sick(mp, XFS_SICK_FS_METADIR);
+		return -EFSCORRUPTED;
+	}
+
+	trace_xfs_metadir_lookup(dp, xname, args.inumber);
+	*ino = args.inumber;
+	return 0;
+}
+
+/*
+ * Look up and read a metadata inode from the metadata directory.  If the path
+ * component doesn't exist, return -ENOENT.
+ */
+int
+xfs_metadir_load(
+	struct xfs_trans	*tp,
+	struct xfs_inode	*dp,
+	const char		*path,
+	enum xfs_metafile_type	metafile_type,
+	struct xfs_inode	**ipp)
+{
+	struct xfs_name		xname;
+	xfs_ino_t		ino;
+	int			error;
+
+	xfs_metadir_set_xname(&xname, path, XFS_DIR3_FT_UNKNOWN);
+
+	xfs_ilock(dp, XFS_ILOCK_EXCL);
+	error = xfs_metadir_lookup(tp, dp, &xname, &ino);
+	xfs_iunlock(dp, XFS_ILOCK_EXCL);
+	if (error)
+		return error;
+	return xfs_trans_metafile_iget(tp, ino, metafile_type, ipp);
+}
+
+/*
+ * Unlock and release resources after committing (or cancelling) a metadata
+ * directory tree operation.  The caller retains its reference to @upd->ip
+ * and must release it explicitly.
+ */
+static inline void
+xfs_metadir_teardown(
+	struct xfs_metadir_update	*upd,
+	int				error)
+{
+	trace_xfs_metadir_teardown(upd, error);
+
+	if (upd->ppargs) {
+		xfs_parent_finish(upd->dp->i_mount, upd->ppargs);
+		upd->ppargs = NULL;
+	}
+
+	if (upd->ip) {
+		if (upd->ip_locked)
+			xfs_iunlock(upd->ip, XFS_ILOCK_EXCL);
+		upd->ip_locked = false;
+	}
+
+	if (upd->dp_locked)
+		xfs_iunlock(upd->dp, XFS_ILOCK_EXCL);
+	upd->dp_locked = false;
+}
+
+/*
+ * Begin the process of creating a metadata file by allocating transactions
+ * and taking whatever resources we're going to need.
+ */
+int
+xfs_metadir_start_create(
+	struct xfs_metadir_update	*upd)
+{
+	struct xfs_mount		*mp = upd->dp->i_mount;
+	int				error;
+
+	ASSERT(upd->dp != NULL);
+	ASSERT(upd->ip == NULL);
+	ASSERT(xfs_has_metadir(mp));
+	ASSERT(upd->metafile_type != XFS_METAFILE_UNKNOWN);
+
+	error = xfs_parent_start(mp, &upd->ppargs);
+	if (error)
+		return error;
+
+	/*
+	 * If we ever need the ability to create rt metadata files on a
+	 * pre-metadir filesystem, we'll need to dqattach the parent here.
+	 * Currently we assume that mkfs will create the files and quotacheck
+	 * will account for them.
+	 */
+
+	error = xfs_trans_alloc(mp, &M_RES(mp)->tr_create,
+			xfs_create_space_res(mp, MAXNAMELEN), 0, 0, &upd->tp);
+	if (error)
+		goto out_teardown;
+
+	/*
+	 * Lock the parent directory if there is one.  We can't ijoin it to
+	 * the transaction until after the child file has been created.
+	 */
+	xfs_ilock(upd->dp, XFS_ILOCK_EXCL | XFS_ILOCK_PARENT);
+	upd->dp_locked = true;
+
+	trace_xfs_metadir_start_create(upd);
+	return 0;
+out_teardown:
+	xfs_metadir_teardown(upd, error);
+	return error;
+}
+
+/*
+ * Create a metadata inode with the given @mode, and insert it into the
+ * metadata directory tree at the given @upd->path.  The path up to the final
+ * component must already exist.  The final path component must not exist.
+ *
+ * The new metadata inode will be attached to the update structure @upd->ip,
+ * with the ILOCK held until the caller releases it.
+ *
+ * NOTE: This function may return a new inode to the caller even if it returns
+ * a negative error code.  If an inode is passed back, the caller must finish
+ * setting up the inode before releasing it.
+ */
+int
+xfs_metadir_create(
+	struct xfs_metadir_update	*upd,
+	umode_t				mode)
+{
+	struct xfs_icreate_args		args = {
+		.pip			= upd->dp,
+		.mode			= mode,
+	};
+	struct xfs_name			xname;
+	struct xfs_dir_update		du = {
+		.dp			= upd->dp,
+		.name			= &xname,
+		.ppargs			= upd->ppargs,
+	};
+	struct xfs_mount		*mp = upd->dp->i_mount;
+	xfs_ino_t			ino;
+	unsigned int			resblks;
+	int				error;
+
+	xfs_assert_ilocked(upd->dp, XFS_ILOCK_EXCL);
+
+	/* Check that the name does not already exist in the directory. */
+	xfs_metadir_set_xname(&xname, upd->path, XFS_DIR3_FT_UNKNOWN);
+	error = xfs_metadir_lookup(upd->tp, upd->dp, &xname, &ino);
+	switch (error) {
+	case -ENOENT:
+		break;
+	case 0:
+		error = -EEXIST;
+		fallthrough;
+	default:
+		return error;
+	}
+
+	/*
+	 * A newly created regular or special file just has one directory
+	 * entry pointing to them, but a directory also the "." entry
+	 * pointing to itself.
+	 */
+	error = xfs_dialloc(&upd->tp, &args, &ino);
+	if (error)
+		return error;
+	error = xfs_icreate(upd->tp, ino, &args, &upd->ip);
+	if (error)
+		return error;
+	du.ip = upd->ip;
+	xfs_metafile_set_iflag(upd->tp, upd->ip, upd->metafile_type);
+	upd->ip_locked = true;
+
+	/*
+	 * Join the directory inode to the transaction.  We do not do it
+	 * earlier because xfs_dialloc rolls the transaction.
+	 */
+	xfs_trans_ijoin(upd->tp, upd->dp, 0);
+
+	/* Create the entry. */
+	if (S_ISDIR(args.mode))
+		resblks = xfs_mkdir_space_res(mp, xname.len);
+	else
+		resblks = xfs_create_space_res(mp, xname.len);
+	xname.type = xfs_mode_to_ftype(args.mode);
+
+	trace_xfs_metadir_try_create(upd);
+
+	error = xfs_dir_create_child(upd->tp, resblks, &du);
+	if (error)
+		return error;
+
+	/* Metadir files are not accounted to quota. */
+
+	trace_xfs_metadir_create(upd);
+
+	return 0;
+}
+
+#ifndef __KERNEL__
+/*
+ * Begin the process of linking a metadata file by allocating transactions
+ * and locking whatever resources we're going to need.
+ */
+int
+xfs_metadir_start_link(
+	struct xfs_metadir_update	*upd)
+{
+	struct xfs_mount		*mp = upd->dp->i_mount;
+	unsigned int			resblks;
+	int				nospace_error = 0;
+	int				error;
+
+	ASSERT(upd->dp != NULL);
+	ASSERT(upd->ip != NULL);
+	ASSERT(xfs_has_metadir(mp));
+
+	error = xfs_parent_start(mp, &upd->ppargs);
+	if (error)
+		return error;
+
+	resblks = xfs_link_space_res(mp, MAXNAMELEN);
+	error = xfs_trans_alloc_dir(upd->dp, &M_RES(mp)->tr_link, upd->ip,
+			&resblks, &upd->tp, &nospace_error);
+	if (error)
+		goto out_teardown;
+	if (!resblks) {
+		/* We don't allow reservationless updates. */
+		xfs_trans_cancel(upd->tp);
+		upd->tp = NULL;
+		xfs_iunlock(upd->dp, XFS_ILOCK_EXCL);
+		xfs_iunlock(upd->ip, XFS_ILOCK_EXCL);
+		error = nospace_error;
+		goto out_teardown;
+	}
+
+	upd->dp_locked = true;
+	upd->ip_locked = true;
+
+	trace_xfs_metadir_start_link(upd);
+	return 0;
+out_teardown:
+	xfs_metadir_teardown(upd, error);
+	return error;
+}
+
+/*
+ * Link the metadata directory given by @path to the inode @upd->ip.
+ * The path (up to the final component) must already exist, but the final
+ * component must not already exist.
+ */
+int
+xfs_metadir_link(
+	struct xfs_metadir_update	*upd)
+{
+	struct xfs_name			xname;
+	struct xfs_dir_update		du = {
+		.dp			= upd->dp,
+		.name			= &xname,
+		.ip			= upd->ip,
+		.ppargs			= upd->ppargs,
+	};
+	struct xfs_mount		*mp = upd->dp->i_mount;
+	xfs_ino_t			ino;
+	unsigned int			resblks;
+	int				error;
+
+	xfs_assert_ilocked(upd->dp, XFS_ILOCK_EXCL);
+	xfs_assert_ilocked(upd->ip, XFS_ILOCK_EXCL);
+
+	/* Look up the name in the current directory. */
+	xfs_metadir_set_xname(&xname, upd->path,
+			xfs_mode_to_ftype(VFS_I(upd->ip)->i_mode));
+	error = xfs_metadir_lookup(upd->tp, upd->dp, &xname, &ino);
+	switch (error) {
+	case -ENOENT:
+		break;
+	case 0:
+		error = -EEXIST;
+		fallthrough;
+	default:
+		return error;
+	}
+
+	resblks = xfs_link_space_res(mp, xname.len);
+	error = xfs_dir_add_child(upd->tp, resblks, &du);
+	if (error)
+		return error;
+
+	trace_xfs_metadir_link(upd);
+
+	return 0;
+}
+#endif /* ! __KERNEL__ */
+
+/* Commit a metadir update and unlock/drop all resources. */
+int
+xfs_metadir_commit(
+	struct xfs_metadir_update	*upd)
+{
+	int				error;
+
+	trace_xfs_metadir_commit(upd);
+
+	error = xfs_trans_commit(upd->tp);
+	upd->tp = NULL;
+
+	xfs_metadir_teardown(upd, error);
+	return error;
+}
+
+/* Cancel a metadir update and unlock/drop all resources. */
+void
+xfs_metadir_cancel(
+	struct xfs_metadir_update	*upd,
+	int				error)
+{
+	trace_xfs_metadir_cancel(upd);
+
+	xfs_trans_cancel(upd->tp);
+	upd->tp = NULL;
+
+	xfs_metadir_teardown(upd, error);
+}
+
+/* Create a metadata for the last component of the path. */
+int
+xfs_metadir_mkdir(
+	struct xfs_inode		*dp,
+	const char			*path,
+	struct xfs_inode		**ipp)
+{
+	struct xfs_metadir_update	upd = {
+		.dp			= dp,
+		.path			= path,
+		.metafile_type		= XFS_METAFILE_DIR,
+	};
+	int				error;
+
+	if (xfs_is_shutdown(dp->i_mount))
+		return -EIO;
+
+	/* Allocate a transaction to create the last directory. */
+	error = xfs_metadir_start_create(&upd);
+	if (error)
+		return error;
+
+	/* Create the subdirectory and take our reference. */
+	error = xfs_metadir_create(&upd, S_IFDIR);
+	if (error)
+		goto out_cancel;
+
+	error = xfs_metadir_commit(&upd);
+	if (error)
+		goto out_irele;
+
+	xfs_finish_inode_setup(upd.ip);
+	*ipp = upd.ip;
+	return 0;
+
+out_cancel:
+	xfs_metadir_cancel(&upd, error);
+out_irele:
+	/* Have to finish setting up the inode to ensure it's deleted. */
+	if (upd.ip) {
+		xfs_finish_inode_setup(upd.ip);
+		xfs_irele(upd.ip);
+	}
+	return error;
+}