Merge pull request #28833 from DaanDeMeyer/copy-subvolume

repart: Add Subvolumes= setting

src/basic/btrfs.c

@@ -0,0 +1,91 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <linux/btrfs.h>
+#include <sys/ioctl.h>
+
+#include "btrfs.h"
+#include "fd-util.h"
+#include "fs-util.h"
+#include "path-util.h"
+
+int btrfs_validate_subvolume_name(const char *name) {
+
+        if (!filename_is_valid(name))
+                return -EINVAL;
+
+        if (strlen(name) > BTRFS_SUBVOL_NAME_MAX)
+                return -E2BIG;
+
+        return 0;
+}
+
+static int extract_subvolume_name(const char *path, char **ret) {
+        _cleanup_free_ char *fn = NULL;
+        int r;
+
+        assert(path);
+        assert(ret);
+
+        r = path_extract_filename(path, &fn);
+        if (r < 0)
+                return r;
+
+        r = btrfs_validate_subvolume_name(fn);
+        if (r < 0)
+                return r;
+
+        *ret = TAKE_PTR(fn);
+        return 0;
+}
+
+int btrfs_subvol_make(int dir_fd, const char *path) {
+        struct btrfs_ioctl_vol_args args = {};
+        _cleanup_free_ char *subvolume = NULL;
+        _cleanup_close_ int fd = -EBADF;
+        int r;
+
+        assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+        assert(!isempty(path));
+
+        r = extract_subvolume_name(path, &subvolume);
+        if (r < 0)
+                return r;
+
+        r = path_extract_directory(path, NULL);
+        if (r >= 0) {
+                fd = open_parent_at(dir_fd, path, O_RDONLY|O_CLOEXEC|O_CLOEXEC, 0);
+                if (fd < 0)
+                        return fd;
+
+                dir_fd = fd;
+        }
+
+        strncpy(args.name, subvolume, sizeof(args.name)-1);
+
+        return RET_NERRNO(ioctl(dir_fd, BTRFS_IOC_SUBVOL_CREATE, &args));
+}
+
+int btrfs_subvol_make_fallback(int dir_fd, const char *path, mode_t mode) {
+        mode_t old, combined;
+        int r;
+
+        assert(path);
+
+        /* Let's work like mkdir(), i.e. take the specified mode, and mask it with the current umask. */
+        old = umask(~mode);
+        combined = old | ~mode;
+        if (combined != ~mode)
+                umask(combined);
+        r = btrfs_subvol_make(dir_fd, path);
+        umask(old);
+
+        if (r >= 0)
+                return 1; /* subvol worked */
+        if (r != -ENOTTY)
+                return r;
+
+        if (mkdirat(dir_fd, path, mode) < 0)
+                return -errno;
+
+        return 0; /* plain directory */
+}

src/basic/btrfs.h

@@ -0,0 +1,9 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <fcntl.h>
+
+int btrfs_validate_subvolume_name(const char *name);
+
+int btrfs_subvol_make(int dir_fd, const char *path);
+
+int btrfs_subvol_make_fallback(int dir_fd, const char *path, mode_t mode);

src/basic/fs-util.c

@@ -9,6 +9,7 @@
 #include <unistd.h>
 
 #include "alloc-util.h"
+#include "btrfs.h"
 #include "dirent-util.h"
 #include "fd-util.h"
 #include "fileio.h"
@@ -1110,7 +1111,10 @@ int xopenat(int dir_fd, const char *path, int open_flags, XOpenFlags xopen_flags
         }
 
         if (FLAGS_SET(open_flags, O_DIRECTORY|O_CREAT)) {
-                r = RET_NERRNO(mkdirat(dir_fd, path, mode));
+                if (FLAGS_SET(xopen_flags, XO_SUBVOLUME))
+                        r = btrfs_subvol_make_fallback(dir_fd, path, mode);
+                else
+                        r = RET_NERRNO(mkdirat(dir_fd, path, mode));
                 if (r == -EEXIST) {
                         if (FLAGS_SET(open_flags, O_EXCL))
                                 return -EEXIST;

src/basic/fs-util.h

@@ -133,7 +133,8 @@ int open_mkdir_at(int dirfd, const char *path, int flags, mode_t mode);
 int openat_report_new(int dirfd, const char *pathname, int flags, mode_t mode, bool *ret_newly_created);
 
 typedef enum XOpenFlags {
-        XO_LABEL = 1 << 0,
+        XO_LABEL     = 1 << 0,
+        XO_SUBVOLUME = 1 << 1,
 } XOpenFlags;
 
 int xopenat(int dir_fd, const char *path, int open_flags, XOpenFlags xopen_flags, mode_t mode);

src/basic/meson.build

@@ -8,6 +8,7 @@ basic_sources = files(
         'argv-util.c',
         'arphrd-util.c',
         'audit-util.c',
+        'btrfs.c',
         'build.c',
         'bus-label.c',
         'cap-list.c',

src/basic/mkdir.c

@@ -5,6 +5,7 @@
 #include <string.h>
 
 #include "alloc-util.h"
+#include "btrfs.h"
 #include "chase.h"
 #include "fd-util.h"
 #include "format-util.h"
@@ -209,7 +210,7 @@ int mkdir_p_safe(const char *prefix, const char *path, mode_t mode, uid_t uid, g
         return mkdir_p_internal(prefix, path, mode, uid, gid, flags, mkdirat_errno_wrapper);
 }
 
-int mkdir_p_root(const char *root, const char *p, uid_t uid, gid_t gid, mode_t m) {
+int mkdir_p_root(const char *root, const char *p, uid_t uid, gid_t gid, mode_t m, char **subvolumes) {
         _cleanup_free_ char *pp = NULL, *bn = NULL;
         _cleanup_close_ int dfd = -EBADF;
         int r;
@@ -227,7 +228,7 @@ int mkdir_p_root(const char *root, const char *p, uid_t uid, gid_t gid, mode_t m
                 return r;
         else {
                 /* Extracting the parent dir worked, hence we aren't top-level? Recurse up first. */
-                r = mkdir_p_root(root, pp, uid, gid, m);
+                r = mkdir_p_root(root, pp, uid, gid, m, subvolumes);
                 if (r < 0)
                         return r;
 
@@ -242,11 +243,15 @@ int mkdir_p_root(const char *root, const char *p, uid_t uid, gid_t gid, mode_t m
         if (r < 0)
                 return r;
 
-        if (mkdirat(dfd, bn, m) < 0) {
-                if (errno == EEXIST)
+        if (path_strv_contains(subvolumes, p))
+                r = btrfs_subvol_make_fallback(dfd, bn, m);
+        else
+                r = RET_NERRNO(mkdirat(dfd, bn, m));
+        if (r < 0) {
+                if (r == -EEXIST)
                         return 0;
 
-                return -errno;
+                return r;
         }
 
         if (uid_is_valid(uid) || gid_is_valid(gid)) {

src/basic/mkdir.h

@@ -23,7 +23,7 @@ static inline int mkdir_parents(const char *path, mode_t mode) {
 int mkdir_parents_safe(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags);
 int mkdir_p(const char *path, mode_t mode);
 int mkdir_p_safe(const char *prefix, const char *path, mode_t mode, uid_t uid, gid_t gid, MkdirFlags flags);
-int mkdir_p_root(const char *root, const char *p, uid_t uid, gid_t gid, mode_t m);
+int mkdir_p_root(const char *root, const char *p, uid_t uid, gid_t gid, mode_t m, char **subvolumes);
 
 /* The following are used to implement the mkdir_xyz_label() calls, don't use otherwise. */
 typedef int (*mkdirat_func_t)(int dir_fd, const char *pathname, mode_t mode);

src/basic/path-util.c

@@ -1116,7 +1116,9 @@ int path_extract_directory(const char *path, char **ret) {
         if (!path_is_valid(a))
                 return -EINVAL;
 
-        *ret = TAKE_PTR(a);
+        if (ret)
+                *ret = TAKE_PTR(a);
+
         return 0;
 }