> Op 3 dec. 2018, om 14:38 heeft Andrzej Lossowsk <alos...@wp.pl> het volgende
> geschreven:
>
> Currently after pivot to the USB disk (extroot),
> configuration and data from original root overlay are gone.
> Still accessible, but all previous configuration steps must be repeated
> (or data from original root overlay must be copied to new USB disk overlay).
>
> The idea is to "merge" original root overlay with overlay from the USB disk.
> Using overlayfs multiple lower layers it can be done.
> All data from original root overlay will be accessible (as readonly layer)
> after pivot to the USB disk.
>
> Original root overlay (for exmaple /dev/mtdblock3) will be mounted to
> /overlay/internal (as readonly)
> Upper directory from original root overlay (/dev/mtdblock3/upper) will be the
> top (readonly layer),
> then "/" will be the bottom layer (readonly layer), an extroot still will be
> upper (writable layer).
>
> Signed-off-by: Andrzej Lossowski <alos...@wp.pl>
> ---
> libfstools/extroot.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++-
> libfstools/libfstools.h | 3 +-
> libfstools/mount.c | 21 +++++++++-----
> libfstools/overlay.c | 6 ++--
> libfstools/snapshot.c | 2 +-
> 5 files changed, 92 insertions(+), 13 deletions(-)
>
> diff --git a/libfstools/extroot.c b/libfstools/extroot.c
> index 418df94..d7590eb 100644
> --- a/libfstools/extroot.c
> +++ b/libfstools/extroot.c
> @@ -22,6 +22,7 @@
> #include <libgen.h>
>
> #include "libfstools.h"
> +#include "volume.h"
>
> char const *extroot_prefix = NULL;
>
> @@ -104,7 +105,7 @@ int mount_extroot(void)
> if (mount_move("/tmp/extroot", "", "/overlay"))
> {
> ULOG_ERR("moving extroot failed -
> continue normal boot\n");
> umount("/tmp/extroot/overlay");
> - } else if (fopivot("/overlay", "/rom")) {
> + } else if (fopivot_multi("/overlay", "/rom")) {
> ULOG_ERR("switching to extroot failed -
> continue normal boot\n");
> umount("/overlay");
> } else {
> @@ -119,3 +120,73 @@ int mount_extroot(void)
> }
> return -1;
> }
> +
> +static int mount_internal_overlay()
> +{
> + struct volume *v = volume_find("rootfs_data");
> + char *mp;
> + char *fstype;
> +
> + if (!v)
> + return -1;
> +
> + volume_init(v);
> + mp = find_mount_point(v->blk, 0);
> + if (mp) {
> + ULOG_ERR("rootfs_data:%s is already mounted as %s\n", v->blk,
> mp);
> + return -1;
> + }
> +
> + switch (volume_identify(v)) {
> + case FS_EXT4:
> + fstype = "ext4";
> + break;
> + case FS_F2FS:
> + fstype = "f2fs";
> + break;
> + case FS_UBIFS:
> + fstype = "ubifs";
> + break;
> + case FS_JFFS2:
> + default:
> + fstype = "jffs2";
> + break;
> + }
> +
> + if (mkdir("/tmp/overlay", 0755)) {
> + ULOG_ERR("failed to mkdir /tmp/overlay: %m\n");
> + return -1;
> + }
> +
> + if (mount(v->blk, "/tmp/overlay", fstype, MS_NOATIME | MS_RDONLY,
> NULL)) {
> + ULOG_ERR("failed to mount -t %s %s /tmp/overlay: %m\n", fstype,
> v->blk);
> + return -1;
> + }
> +
> + return 0;
> +}
> +
> +int fopivot_multi(char *rw_root, char *ro_root)
> +{
> + if (mount_internal_overlay()) {
> + ULOG_ERR("mounting /tmp/overlay failed\n");
> + return -1;
> + }
> +
> + if (mkdir("/overlay/internal", 0755)) {
> + ULOG_ERR("failed to mkdir /overlay/internal: %m\n");
> + return -1;
> + }
> +
> + if (mount_move("/tmp/overlay", "/overlay/internal", "")) {
> + umount("/tmp/overlay");
> + return -1;
> + }
> +
> + if (fopivot(rw_root, ro_root, "/overlay/internal/upper")) {
> + umount("/overlay/internal");
> + return -1;
> + }
> +
> + return 0;
> +}
> \ No newline at end of file
> diff --git a/libfstools/libfstools.h b/libfstools/libfstools.h
> index f27307a..8554f4c 100644
> --- a/libfstools/libfstools.h
> +++ b/libfstools/libfstools.h
> @@ -45,7 +45,8 @@ extern int mount_overlay(struct volume *v);
>
> extern int mount_move(const char *oldroot, const char *newroot, const char
> *dir);
> extern int pivot(char *new, char *old);
> -extern int fopivot(char *rw_root, char *ro_root);
> +extern int fopivot(char *rw_root, char *ro_lowerlevel0, char
> *ro_lowerlevel1);
> +extern int fopivot_multi(char *rw_root, char *ro_root);
> extern int ramoverlay(void);
>
> extern int find_overlay_mount(char *overlay);
> diff --git a/libfstools/mount.c b/libfstools/mount.c
> index c7f2789..619ac20 100644
> --- a/libfstools/mount.c
> +++ b/libfstools/mount.c
> @@ -89,12 +89,13 @@ pivot(char *new, char *old)
> * fopivot - switch to overlay using passed dir as upper one
> *
> * @rw_root: writable directory that will be used as upper dir
> - * @ro_root: directory where old root will be put
> + * @ro_root: directory where old root will be put
> + * @ro_lowerlevel1: directory where internal overlay will be put
> */
> int
> -fopivot(char *rw_root, char *ro_root)
> +fopivot(char *rw_root, char *ro_root, char *ro_lowerlevel1)
> {
> - char overlay[64], mount_options[64];
> + char overlay[64], mount_options[128];
>
> if (find_filesystem("overlay")) {
> ULOG_ERR("BUG: no suitable fs found\n");
> @@ -110,15 +111,21 @@ fopivot(char *rw_root, char *ro_root)
> */
> snprintf(mount_options, sizeof(mount_options),
> "lowerdir=/,upperdir=%s", rw_root);
> if (mount(overlay, "/mnt", "overlayfs", MS_NOATIME, mount_options)) {
> - char upperdir[64], workdir[64], upgrade[64], upgrade_dest[64];
> + char upperdir[64], workdir[64], upgrade[64], upgrade_dest[64],
> lowerdir[64];
> struct stat st;
>
> snprintf(upperdir, sizeof(upperdir), "%s/upper", rw_root);
> snprintf(workdir, sizeof(workdir), "%s/work", rw_root);
> snprintf(upgrade, sizeof(upgrade), "%s/sysupgrade.tgz",
> rw_root);
> snprintf(upgrade_dest, sizeof(upgrade_dest),
> "%s/sysupgrade.tgz", upperdir);
> - snprintf(mount_options, sizeof(mount_options),
> "lowerdir=/,upperdir=%s,workdir=%s",
> - upperdir, workdir);
> +
> + if (ro_lowerlevel1)
> + snprintf(lowerdir, sizeof(lowerdir), "%s:/",
> ro_lowerlevel1);
> + else
> + snprintf(lowerdir, sizeof(lowerdir), "/");
> +
> + snprintf(mount_options, sizeof(mount_options),
> "lowerdir=%s,upperdir=%s,workdir=%s",
> + lowerdir, upperdir, workdir);
>
> /*
> * Overlay FS v23 and later requires both a upper and
> @@ -154,5 +161,5 @@ ramoverlay(void)
> mkdir("/tmp/root", 0755);
> mount("tmpfs", "/tmp/root", "tmpfs", MS_NOATIME, "mode=0755");
>
> - return fopivot("/tmp/root", "/rom");
> + return fopivot("/tmp/root", "/rom", NULL);
> }
> diff --git a/libfstools/overlay.c b/libfstools/overlay.c
> index 14214a3..1a019ed 100644
> --- a/libfstools/overlay.c
> +++ b/libfstools/overlay.c
> @@ -205,7 +205,7 @@ switch2jffs(struct volume *v)
> return -1;
> }
>
> - ret = fopivot("/overlay", "/rom");
> + ret = fopivot("/overlay", "/rom", NULL);
>
> /*
> * Besides copying overlay data from "tmpfs" to "jffs2" we should also
> @@ -320,7 +320,7 @@ jffs2_switch(struct volume *v)
> case FS_UBIFS:
> if (overlay_mount(v, fs_name))
> return -1;
> - if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay",
> "/rom")) {
> + if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay",
> "/rom", NULL)) {
> ULOG_ERR("switching to %s failed\n", fs_name);
> return -1;
> }
> @@ -439,7 +439,7 @@ int mount_overlay(struct volume *v)
>
> fs_name = overlay_fs_name(volume_identify(v));
> ULOG_INFO("switching to %s overlay\n", fs_name);
> - if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom")) {
> + if (mount_move("/tmp", "", "/overlay") || fopivot("/overlay", "/rom",
> NULL)) {
> ULOG_ERR("switching to %s failed - fallback to ramoverlay\n",
> fs_name);
> return ramoverlay();
> }
> diff --git a/libfstools/snapshot.c b/libfstools/snapshot.c
> index 4870cf7..c22cdc0 100644
> --- a/libfstools/snapshot.c
> +++ b/libfstools/snapshot.c
> @@ -320,7 +320,7 @@ static int
> _ramoverlay(char *rom, char *overlay)
> {
> mount("tmpfs", overlay, "tmpfs", MS_NOATIME, "mode=0755");
> - return fopivot(overlay, rom);
> + return fopivot(overlay, rom, NULL);
> }
>
> int
> --
> 2.14.1.windows.1
>
>
>
> _______________________________________________
> openwrt-devel mailing list
> openwrt-devel@lists.openwrt.org
> https://lists.openwrt.org/mailman/listinfo/openwrt-devel
Any chance that this nice patch will get reviewed/merged ?
Paul
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