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Merge pull request #2864 from cgwalters/prepare-root-prepare-composefs
prepare-root: Move sysroot.tmp creation earlier
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commit
0dd2788410
@ -36,11 +36,16 @@
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* hardlinked chroot() targets are maintained, this one does the equivalent
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* of chroot().
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*
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* # ostree-prepare-root.service
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*
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* If using systemd, an excellent reference is `man bootup`. This
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* service runs Before=initrd-root-fs.target. At this point it's
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* assumed that the block storage and root filesystem are mounted at
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* /sysroot - i.e. /sysroot points to the *physical* root before
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* this service runs. After, `/` is the deployment root.
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* this service runs. After, `/` is the deployment root, and /sysroot is
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* the physical root.
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*
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* # Running as pid 1
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*
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* There is also a secondary mode for this service when an initrd isn't
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* used - instead the binary must be statically linked (and the kernel
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@ -78,6 +83,9 @@
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SD_ID128_MAKE (71, 70, 33, 6a, 73, ba, 46, 01, ba, d3, 1a, f8, 88, aa, 0d, f7)
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#endif
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// A temporary mount point
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#define TMP_SYSROOT "/sysroot.tmp"
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#include "ostree-mount-util.h"
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static inline bool
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@ -202,6 +210,11 @@ main (int argc, char *argv[])
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we_mounted_proc = 1;
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}
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/* This is the final target where we should prepare the rootfs. The usual
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* case with systemd in the initramfs is that root_mountpoint = "/sysroot".
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* In the fastboot embedded case we're pid1 and will setup / ourself, and
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* then root_mountpoint = "/".
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* */
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const char *root_mountpoint = realpath (root_arg, NULL);
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if (root_mountpoint == NULL)
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err (EXIT_FAILURE, "realpath(\"%s\")", root_arg);
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@ -234,16 +247,23 @@ main (int argc, char *argv[])
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if (mount (NULL, "/", NULL, MS_REC | MS_PRIVATE | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to make \"/\" private mount");
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/* Make deploy_path a bind mount, so we can move it later */
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if (mount (deploy_path, deploy_path, NULL, MS_BIND | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to make initial bind mount %s", deploy_path);
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if (mkdir (TMP_SYSROOT, 0755) < 0)
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err (EXIT_FAILURE, "couldn't create temporary sysroot %s", TMP_SYSROOT);
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/* chdir to our new root. We need to do this after bind-mounting it over
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* itself otherwise our cwd is still on the non-bind-mounted filesystem
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* below. */
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/* Run in the deploy_path dir so we can use relative paths below */
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if (chdir (deploy_path) < 0)
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err (EXIT_FAILURE, "failed to chdir to deploy_path");
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/* Currently always false */
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bool using_composefs = false;
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if (!using_composefs)
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{
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/* The deploy root starts out bind mounted to sysroot.tmp */
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if (mount (deploy_path, TMP_SYSROOT, NULL, MS_BIND | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to make initial bind mount %s", deploy_path);
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}
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/* This will result in a system with /sysroot read-only. Thus, two additional
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* writable bind-mounts (for /etc and /var) are required later on. */
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if (sysroot_readonly)
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@ -269,7 +289,7 @@ main (int argc, char *argv[])
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{
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if (snprintf (srcpath, sizeof (srcpath), "%s/boot", root_mountpoint) < 0)
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err (EXIT_FAILURE, "failed to assemble /boot path");
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if (mount (srcpath, "boot", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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if (mount (srcpath, TMP_SYSROOT "/boot", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to bind mount %s to boot", srcpath);
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}
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}
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@ -277,13 +297,15 @@ main (int argc, char *argv[])
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/* Prepare /etc.
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* No action required if sysroot is writable. Otherwise, a bind-mount for
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* the deployment needs to be created and remounted as read/write. */
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if (sysroot_readonly)
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if (sysroot_readonly || using_composefs)
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{
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/* Bind-mount /etc (at deploy path), and remount as writable. */
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if (mount ("etc", "etc", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to prepare /etc bind-mount at %s", srcpath);
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if (mount ("etc", "etc", NULL, MS_BIND | MS_REMOUNT | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to make writable /etc bind-mount at %s", srcpath);
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if (mount ("etc", TMP_SYSROOT "/etc", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to prepare /etc bind-mount at /sysroot.tmp/etc");
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if (mount (TMP_SYSROOT "/etc", TMP_SYSROOT "/etc", NULL, MS_BIND | MS_REMOUNT | MS_SILENT,
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NULL)
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< 0)
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err (EXIT_FAILURE, "failed to make writable /etc bind-mount at /sysroot.tmp/etc");
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}
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/* Prepare /usr.
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@ -291,28 +313,31 @@ main (int argc, char *argv[])
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if (lstat (".usr-ovl-work", &stbuf) == 0)
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{
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/* Do we have a persistent overlayfs for /usr? If so, mount it now. */
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const char usr_ovl_options[] = "lowerdir=usr,upperdir=.usr-ovl-upper,workdir=.usr-ovl-work";
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const char usr_ovl_options[]
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= "lowerdir=" TMP_SYSROOT "/usr,upperdir=.usr-ovl-upper,workdir=.usr-ovl-work";
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/* Except overlayfs barfs if we try to mount it on a read-only
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* filesystem. For this use case I think admins are going to be
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* okay if we remount the rootfs here, rather than waiting until
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* later boot and `systemd-remount-fs.service`.
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*/
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if (path_is_on_readonly_fs ("."))
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if (path_is_on_readonly_fs (TMP_SYSROOT))
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{
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if (mount (".", ".", NULL, MS_REMOUNT | MS_SILENT, NULL) < 0)
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if (mount (TMP_SYSROOT, TMP_SYSROOT, NULL, MS_REMOUNT | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to remount rootfs writable (for overlayfs)");
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}
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if (mount ("overlay", "usr", "overlay", MS_SILENT, usr_ovl_options) < 0)
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if (mount ("overlay", TMP_SYSROOT "/usr", "overlay", MS_SILENT, usr_ovl_options) < 0)
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err (EXIT_FAILURE, "failed to mount /usr overlayfs");
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}
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else
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else if (!using_composefs)
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{
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/* Otherwise, a read-only bind mount for /usr */
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if (mount ("usr", "usr", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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/* Otherwise, a read-only bind mount for /usr. (Not needed for composefs) */
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if (mount (TMP_SYSROOT "/usr", TMP_SYSROOT "/usr", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to bind mount (class:readonly) /usr");
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if (mount ("usr", "usr", NULL, MS_BIND | MS_REMOUNT | MS_RDONLY | MS_SILENT, NULL) < 0)
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if (mount (TMP_SYSROOT "/usr", TMP_SYSROOT "/usr", NULL,
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MS_BIND | MS_REMOUNT | MS_RDONLY | MS_SILENT, NULL)
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< 0)
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err (EXIT_FAILURE, "failed to bind mount (class:readonly) /usr");
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}
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@ -345,7 +370,7 @@ main (int argc, char *argv[])
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*/
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if (mount_var)
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{
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if (mount ("../../var", "var", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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if (mount ("../../var", TMP_SYSROOT "/var", NULL, MS_BIND | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to bind mount ../../var to var");
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}
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@ -357,6 +382,9 @@ main (int argc, char *argv[])
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if (!running_as_pid1)
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touch_run_ostree ();
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if (chdir (TMP_SYSROOT) < 0)
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err (EXIT_FAILURE, "failed to chdir to " TMP_SYSROOT);
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if (strcmp (root_mountpoint, "/") == 0)
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{
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/* pivot_root rotates two mount points around. In this instance . (the
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@ -371,32 +399,22 @@ main (int argc, char *argv[])
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else
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{
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/* In this instance typically we have our ready made-up up root at
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* /sysroot/ostree/deploy/.../ (deploy_path) and the real rootfs at
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* /sysroot (root_mountpoint). We want to end up with our made-up root at
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* /sysroot/ and the real rootfs under /sysroot/sysroot as systemd will be
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* responsible for moving /sysroot to /.
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*
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* We need to do this in 3 moves to avoid trying to move /sysroot under
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* itself:
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*
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* 1. /sysroot/ostree/deploy/... -> /sysroot.tmp
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* 2. /sysroot -> /sysroot.tmp/sysroot
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* 3. /sysroot.tmp -> /sysroot
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* /sysroot.tmp and the physical root at /sysroot (root_mountpoint).
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* We want to end up with our deploy root at /sysroot/ and the physical
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* root under /sysroot/sysroot as systemd will be responsible for
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* moving /sysroot to /.
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*/
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if (mkdir ("/sysroot.tmp", 0755) < 0)
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err (EXIT_FAILURE, "couldn't create temporary sysroot /sysroot.tmp");
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if (mount (deploy_path, "/sysroot.tmp", NULL, MS_MOVE | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to MS_MOVE '%s' to '/sysroot.tmp'", deploy_path);
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if (mount (root_mountpoint, "sysroot", NULL, MS_MOVE | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to MS_MOVE '%s' to 'sysroot'", root_mountpoint);
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if (mount (".", root_mountpoint, NULL, MS_MOVE | MS_SILENT, NULL) < 0)
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err (EXIT_FAILURE, "failed to MS_MOVE %s to %s", deploy_path, root_mountpoint);
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err (EXIT_FAILURE, "failed to MS_MOVE %s to %s", ".", root_mountpoint);
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if (rmdir ("/sysroot.tmp") < 0)
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err (EXIT_FAILURE, "couldn't remove temporary sysroot /sysroot.tmp");
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if (chdir (root_mountpoint) < 0)
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err (EXIT_FAILURE, "failed to chdir to %s", root_mountpoint);
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if (rmdir (TMP_SYSROOT) < 0)
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err (EXIT_FAILURE, "couldn't remove temporary sysroot %s", TMP_SYSROOT);
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if (sysroot_readonly)
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{
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