This patch implements the functionality to populate a newly created XFS
filesystem directly from an existing directory structure.
The population process steps are as follows:
- create the root inode before populating content
- recursively process nested directories
- handle regular files, directories, symlinks, char devices, block
devices, and fifos
- preserve file and directory attributes (ownership, permissions)
- preserve timestamps from source files to maintain file history
- preserve file extended attributes
This functionality makes it easier to create populated filesystems
without having to write protofiles manually.
It's particularly useful for reproducible builds.
Signed-off-by: Luca Di Maio <luca.dimaio1@xxxxxxxxx>
---
mkfs/Makefile | 2 +-
mkfs/populate.c | 313 ++++++++++++++++++++++++++++++++++++++++++++++++
mkfs/populate.h | 10 ++
3 files changed, 324 insertions(+), 1 deletion(-)
create mode 100644 mkfs/populate.c
create mode 100644 mkfs/populate.h
diff --git a/mkfs/Makefile b/mkfs/Makefile
index 3d3f08a..75f3dcd 100644
--- a/mkfs/Makefile
+++ b/mkfs/Makefile
@@ -9,7 +9,7 @@ LTCOMMAND = mkfs.xfs
XFS_PROTOFILE = xfs_protofile
HFILES =
-CFILES = proto.c xfs_mkfs.c
+CFILES = populate.c proto.c xfs_mkfs.c
CFGFILES = \
dax_x86_64.conf \
lts_4.19.conf \
diff --git a/mkfs/populate.c b/mkfs/populate.c
new file mode 100644
index 0000000..f5eacbf
--- /dev/null
+++ b/mkfs/populate.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2025 Chainguard, Inc.
+ * All Rights Reserved.
+ * Author: Luca Di Maio <luca.dimaio1@xxxxxxxxx>
+ */
+#include <fcntl.h>
+#include <limits.h>
+#include <linux/fs.h>
+#include <stdio.h>
+#include <string.h>
+#include <dirent.h>
+#include <sys/stat.h>
+#include "libxfs.h"
+#include "proto.h"
+
+static void walk_dir(struct xfs_mount *mp, struct xfs_inode *pip,
+ struct fsxattr *fsxp, char *cur_path);
+
+static void fail(char *msg, int i)
+{
+ fprintf(stderr, _("%s: %s [%d - %s]\n"), progname, msg, i, strerror(i));
+ exit(1);
+}
+
+static int newregfile(char *fname)
+{
+ int fd;
+ off_t size;
+
+ if ((fd = open(fname, O_RDONLY)) < 0 || (size = filesize(fd)) < 0) {
+ fprintf(stderr, _("%s: cannot open %s: %s\n"), progname, fname,
+ strerror(errno));
+ exit(1);
+ }
+
+ return fd;
+}
+
+static void writetimestamps(struct xfs_inode *ip, struct stat statbuf)
+{
+ struct timespec64 ts;
+
+ /*
+ * Copy timestamps from source file to destination inode.
+ * In order to not be influenced by our own access timestamp,
+ * we set atime and ctime to mtime of the source file.
+ * Usually reproducible archives will delete or not register
+ * atime and ctime, for example:
+ * https://www.gnu.org/software/tar/manual/html_section/Reproducibility.html
+ */
+ ts.tv_sec = statbuf.st_mtime;
+ ts.tv_nsec = statbuf.st_mtim.tv_nsec;
+ inode_set_atime_to_ts(VFS_I(ip), ts);
+ inode_set_ctime_to_ts(VFS_I(ip), ts);
+ inode_set_mtime_to_ts(VFS_I(ip), ts);
+
+ return;
+}
+
+static void create_file(struct xfs_mount *mp, struct xfs_inode *pip,
+ struct fsxattr *fsxp, int mode, struct cred creds,
+ struct xfs_name xname, int flags, struct stat file_stat,
+ xfs_dev_t rdev, int fd, char *fname, char *path)
+{
+ int error;
+ struct xfs_parent_args *ppargs = NULL;
+ struct xfs_inode *ip;
+ struct xfs_trans *tp;
+
+ tp = getres(mp, 0);
+ ppargs = newpptr(mp);
+ error = creatproto(&tp, pip, mode, rdev, &creds, fsxp, &ip);
+ if (error)
+ fail(_("Inode allocation failed"), error);
+ libxfs_trans_ijoin(tp, pip, 0);
+ newdirent(mp, tp, pip, &xname, ip, ppargs);
+
+ /*
+ * copy over timestamps
+ */
+ writetimestamps(ip, file_stat);
+
+ libxfs_trans_log_inode(tp, ip, flags);
+ error = -libxfs_trans_commit(tp);
+ if (error)
+ fail(_("Error encountered creating file from prototype file"),
+ error);
+
+ libxfs_parent_finish(mp, ppargs);
+
+ /*
+ * copy over file content, attributes and
+ * timestamps
+ */
+ if (fd != 0) {
+ writefile(ip, fname, fd);
+ writeattrs(ip, fname, fd);
+ close(fd);
+ }
+
+ libxfs_irele(ip);
+}
+
+static void handle_direntry(struct xfs_mount *mp, struct xfs_inode *pip,
+ struct fsxattr *fsxp, char* cur_path, struct dirent *entry)
+{
+ char link_target[PATH_MAX];
+ char path[PATH_MAX];
+ int error;
+ int fd = -1;
+ int flags;
+ int majdev;
+ int mindev;
+ int mode;
+ off_t len;
+ struct cred creds;
+ struct stat file_stat;
+ struct xfs_name xname;
+ struct xfs_parent_args *ppargs = NULL;
+ struct xfs_inode *ip;
+ struct xfs_trans *tp;
+
+ /*
+ * Skip "." and ".." directories
+ */
+ if (strcmp(entry->d_name, ".") == 0 ||
+ strcmp(entry->d_name, "..") == 0) {
+ return;
+ }
+
+ /*
+ * Create the full path to the original file or directory
+ */
+ snprintf(path, sizeof(path), "%s/%s", cur_path, entry->d_name);
+
+ if (lstat(path, &file_stat) < 0) {
+ printf("%s (error accessing)\n", entry->d_name);
+ return;
+ }
+
+ memset(&creds, 0, sizeof(creds));
+ creds.cr_uid = file_stat.st_uid;
+ creds.cr_gid = file_stat.st_gid;
+ xname.name = (unsigned char *)entry->d_name;
+ xname.len = strlen(entry->d_name);
+ xname.type = 0;
+ mode = file_stat.st_mode;
+ flags = XFS_ILOG_CORE;
+ switch (file_stat.st_mode & S_IFMT) {
+ case S_IFDIR:
+ tp = getres(mp, 0);
+ error = creatproto(&tp, pip, mode, 0, &creds, fsxp, &ip);
+ if (error)
+ fail(_("Inode allocation failed"), error);
+ ppargs = newpptr(mp);
+ libxfs_trans_ijoin(tp, pip, 0);
+ xname.type = XFS_DIR3_FT_DIR;
+ newdirent(mp, tp, pip, &xname, ip, ppargs);
+ libxfs_bumplink(tp, pip);
+ libxfs_trans_log_inode(tp, pip, XFS_ILOG_CORE);
+ newdirectory(mp, tp, ip, pip);
+
+ /*
+ * copy over timestamps
+ */
+ writetimestamps(ip, file_stat);
+
+ libxfs_trans_log_inode(tp, ip, flags);
+ error = -libxfs_trans_commit(tp);
+ if (error)
+ fail(_("Directory inode allocation failed."), error);
+
+ libxfs_parent_finish(mp, ppargs);
+ tp = NULL;
+
+ walk_dir(mp, ip, fsxp, path);
+
+ libxfs_irele(ip);
+ break;
+ case S_IFREG:
+ fd = newregfile(path);
+ xname.type = XFS_DIR3_FT_REG_FILE;
+ create_file(mp, pip, fsxp, mode, creds, xname, flags, file_stat,
+ 0, fd, entry->d_name, path);
+ break;
+ case S_IFLNK:
+ len = readlink(path, link_target, PATH_MAX - 1);
+ tp = getres(mp, XFS_B_TO_FSB(mp, len));
+ ppargs = newpptr(mp);
+ error = creatproto(&tp, pip, mode, 0, &creds, fsxp, &ip);
+ if (error)
+ fail(_("Inode allocation failed"), error);
+ writesymlink(tp, ip, link_target, len);
+ libxfs_trans_ijoin(tp, pip, 0);
+ xname.type = XFS_DIR3_FT_SYMLINK;
+ newdirent(mp, tp, pip, &xname, ip, ppargs);
+
+ /*
+ * copy over timestamps
+ */
+ writetimestamps(ip, file_stat);
+
+ libxfs_trans_log_inode(tp, ip, flags);
+ error = -libxfs_trans_commit(tp);
+ if (error)
+ fail(_("Error encountered creating file from prototype file"),
+ error);
+ libxfs_parent_finish(mp, ppargs);
+ libxfs_irele(ip);
+ break;
+ case S_IFCHR:
+ xname.type = XFS_DIR3_FT_CHRDEV;
+ majdev = major(file_stat.st_rdev);
+ mindev = minor(file_stat.st_rdev);
+ create_file(mp, pip, fsxp, mode, creds, xname, flags, file_stat,
+ IRIX_MKDEV(majdev, mindev), 0, entry->d_name, path);
+ break;
+ case S_IFBLK:
+ xname.type = XFS_DIR3_FT_BLKDEV;
+ majdev = major(file_stat.st_rdev);
+ mindev = minor(file_stat.st_rdev);
+ create_file(mp, pip, fsxp, mode, creds, xname, flags, file_stat,
+ IRIX_MKDEV(majdev, mindev), 0, entry->d_name, path);
+ break;
+ case S_IFIFO:
+ flags |= XFS_ILOG_DEV;
+ create_file(mp, pip, fsxp, mode, creds, xname, flags, file_stat,
+ 0, 0, entry->d_name, path);
+ break;
+ default:
+ break;
+ }
+}
+
+/*
+ * walk_dir will recursively list files and directories
+ * and populate the mountpoint *mp with them using handle_direntry().
+ */
+static void walk_dir(struct xfs_mount *mp, struct xfs_inode *pip,
+ struct fsxattr *fsxp, char *cur_path)
+{
+ DIR *dir;
+ struct dirent *entry;
+
+ /*
+ * open input directory and iterate over all entries in it.
+ * when another directory is found, we will recursively call
+ * populatefromdir.
+ */
+ if ((dir = opendir(cur_path)) == NULL)
+ fail(_("cannot open input dir"), 1);
+ while ((entry = readdir(dir)) != NULL) {
+ handle_direntry(mp, pip, fsxp, cur_path, entry);
+ }
+ closedir(dir);
+}
+
+void populate_from_dir(struct xfs_mount *mp, struct xfs_inode *pip,
+ struct fsxattr *fsxp, char *cur_path)
+{
+ int error;
+ int mode;
+ struct cred creds;
+ struct xfs_inode *ip;
+ struct xfs_trans *tp;
+
+ /*
+ * we first ensure we have the root inode
+ */
+ memset(&creds, 0, sizeof(creds));
+ creds.cr_uid = 0;
+ creds.cr_gid = 0;
+ mode = S_IRWXU | S_IRGRP | S_IXGRP | S_IROTH | S_IXOTH;
+ tp = getres(mp, 0);
+ error = creatproto(&tp, pip, mode | S_IFDIR, 0, &creds, fsxp, &ip);
+ if (error)
+ fail(_("Inode allocation failed"), error);
+ pip = ip;
+ mp->m_sb.sb_rootino = ip->i_ino;
+ libxfs_log_sb(tp);
+ newdirectory(mp, tp, ip, pip);
+ libxfs_trans_log_inode(tp, ip, XFS_ILOG_CORE);
+ error = -libxfs_trans_commit(tp);
+ if (error)
+ fail(_("Inode allocation failed"), error);
+
+ libxfs_parent_finish(mp, NULL);
+
+ /*
+ * RT initialization. Do this here to ensure that
+ * the RT inodes get placed after the root inode.
+ */
+ error = create_metadir(mp);
+ if (error)
+ fail(_("Creation of the metadata directory inode failed"),
+ error);
+
+ rtinit(mp);
+
+ /*
+ * now that we have a root inode, let's
+ * walk the input dir and populate the partition
+ */
+ walk_dir(mp, ip, fsxp, cur_path);
+
+ /*
+ * we free up our root inode
+ * only when we finished populating the
+ * root filesystem
+ */
+ libxfs_irele(ip);
+}
diff --git a/mkfs/populate.h b/mkfs/populate.h
new file mode 100644
index 0000000..d65df57
--- /dev/null
+++ b/mkfs/populate.h
@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2025 Chainguard, Inc.
+ * All Rights Reserved.
+ * Author: Luca Di Maio <luca.dimaio1@xxxxxxxxx>
+ */
+#ifndef MKFS_POPULATE_H_
+#define MKFS_POPULATE_H_
+void populate_from_dir(xfs_mount_t *mp, xfs_inode_t *pip, struct fsxattr *fsxp, char *name);
+#endif /* MKFS_POPULATE_H_ */
--
2.49.0
