--- /dev/null
+/* SPDX-License-Identifier: LGPL-2.1+ */
+
+#include <linux/btrfs.h>
+#include <linux/magic.h>
+#include <sys/ioctl.h>
+#include <sys/vfs.h>
+
+#include "blockdev-util.h"
+#include "fs-util.h"
+#include "missing_fs.h"
+#include "missing_magic.h"
+#include "missing_xfs.h"
+#include "resize-fs.h"
+#include "stat-util.h"
+
+int resize_fs(int fd, uint64_t sz) {
+ struct statfs sfs;
+ int r;
+
+ assert(fd >= 0);
+
+ /* Rounds down to next block size */
+
+ if (sz <= 0 || sz == UINT64_MAX)
+ return -ERANGE;
+
+ if (fstatfs(fd, &sfs) < 0)
+ return -errno;
+
+ if (is_fs_type(&sfs, EXT4_SUPER_MAGIC)) {
+ uint64_t u;
+
+ if (sz < EXT4_MINIMAL_SIZE)
+ return -ERANGE;
+
+ u = sz / sfs.f_bsize;
+
+ if (ioctl(fd, EXT4_IOC_RESIZE_FS, &u) < 0)
+ return -errno;
+
+ } else if (is_fs_type(&sfs, BTRFS_SUPER_MAGIC)) {
+ struct btrfs_ioctl_vol_args args = {};
+
+ /* 256M is the minimize size enforced by the btrfs kernel code when resizing (which is
+ * strange btw, as mkfs.btrfs is fine creating file systems > 109M). It will return EINVAL in
+ * that case, let's catch this error beforehand though, and report a more explanatory
+ * error. */
+
+ if (sz < BTRFS_MINIMAL_SIZE)
+ return -ERANGE;
+
+ r = snprintf(args.name, sizeof(args.name), "%" PRIu64, sz);
+ assert((size_t) r < sizeof(args.name));
+
+ if (ioctl(fd, BTRFS_IOC_RESIZE, &args) < 0)
+ return -errno;
+
+ } else if (is_fs_type(&sfs, XFS_SB_MAGIC)) {
+ xfs_fsop_geom_t geo;
+ xfs_growfs_data_t d;
+
+ if (sz < XFS_MINIMAL_SIZE)
+ return -ERANGE;
+
+ if (ioctl(fd, XFS_IOC_FSGEOMETRY, &geo) < 0)
+ return -errno;
+
+ d = (xfs_growfs_data_t) {
+ .imaxpct = geo.imaxpct,
+ .newblocks = sz / geo.blocksize,
+ };
+
+ if (ioctl(fd, XFS_IOC_FSGROWFSDATA, &d) < 0)
+ return -errno;
+
+ } else
+ return -EOPNOTSUPP;
+
+ return 0;
+}
+
+uint64_t minimal_size_by_fs_magic(statfs_f_type_t magic) {
+
+ switch (magic) {
+
+ case (statfs_f_type_t) EXT4_SUPER_MAGIC:
+ return EXT4_MINIMAL_SIZE;
+
+ case (statfs_f_type_t) XFS_SB_MAGIC:
+ return XFS_MINIMAL_SIZE;
+
+ case (statfs_f_type_t) BTRFS_SUPER_MAGIC:
+ return BTRFS_MINIMAL_SIZE;
+
+ default:
+ return UINT64_MAX;
+ }
+}
+
+uint64_t minimal_size_by_fs_name(const char *name) {
+
+ if (streq_ptr(name, "ext4"))
+ return EXT4_MINIMAL_SIZE;
+
+ if (streq_ptr(name, "xfs"))
+ return XFS_MINIMAL_SIZE;
+
+ if (streq_ptr(name, "btrfs"))
+ return BTRFS_MINIMAL_SIZE;
+
+ return UINT64_MAX;
+}