From 35056038c02a7cbd18b57a5f46a373d564c69693 Mon Sep 17 00:00:00 2001 From: =?utf8?q?Rafa=C5=82=20Mi=C5=82ecki?= Date: Wed, 17 Dec 2014 14:22:36 +0100 Subject: [PATCH] document mount_root and block (extroot) a bit MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Also s/fs_data/blkdev_path/ which should make more sense. Signed-off-by: Rafał Miłecki --- block.c | 40 +++++++++++++++++++++++++++++++--------- libfstools/extroot.c | 4 ++++ mount_root.c | 18 ++++++++++++++++++ 3 files changed, 53 insertions(+), 9 deletions(-) diff --git a/block.c b/block.c index 6d187d1..bba68c2 100644 --- a/block.c +++ b/block.c @@ -935,6 +935,9 @@ static int check_extroot(char *path) return -1; } +/* + * Read info about extroot from UCI (using prefix) and mount it. + */ static int mount_extroot(char *cfg) { char overlay[] = "/tmp/extroot/overlay"; @@ -944,9 +947,11 @@ static int mount_extroot(char *cfg) struct mount *m; int err = -1; + /* Load @cfg/etc/config/fstab */ if (config_load(cfg)) return -2; + /* See if there is extroot-specific mount config */ m = find_block(NULL, NULL, NULL, "/"); if (!m) m = find_block(NULL, NULL, NULL, "/overlay"); @@ -957,6 +962,7 @@ static int mount_extroot(char *cfg) return -1; } + /* Find block device pointed by the mount config */ pr = find_block_info(m->uuid, m->label, m->device); if (!pr && delay_root){ @@ -999,7 +1005,7 @@ static int main_extroot(int argc, char **argv) { struct blkid_struct_probe *pr; char fs[32] = { 0 }; - char fs_data[32] = { 0 }; + char blkdev_path[32] = { 0 }; int err = -1; #ifdef UBIFS_EXTROOT libubi_t libubi; @@ -1016,6 +1022,10 @@ static int main_extroot(int argc, char **argv) mkblkdev(); cache_load(1); + /* + * Make sure there is "rootfs" MTD partition or UBI volume. + * TODO: What for? + */ find_block_mtd("rootfs", fs, sizeof(fs)); if (!fs[0]) { #ifdef UBIFS_EXTROOT @@ -1038,14 +1048,24 @@ static int main_extroot(int argc, char **argv) return -3; } - find_block_mtd("rootfs_data", fs_data, sizeof(fs_data)); - if (fs_data[0]) { - pr = find_block_info(NULL, NULL, fs_data); + /* + * Look for "rootfs_data". We will want to mount it and check for + * extroot configuration. + */ + + /* Start with looking for MTD partition */ + find_block_mtd("rootfs_data", blkdev_path, sizeof(blkdev_path)); + if (blkdev_path[0]) { + pr = find_block_info(NULL, NULL, blkdev_path); if (pr && !strcmp(pr->id->name, "jffs2")) { char cfg[] = "/tmp/jffs_cfg"; + /* + * Mount MTD part and try extroot (using + * /etc/config/fstab from that partition) + */ mkdir_p(cfg); - if (!mount(fs_data, cfg, "jffs2", MS_NOATIME, NULL)) { + if (!mount(blkdev_path, cfg, "jffs2", MS_NOATIME, NULL)) { err = mount_extroot(cfg); umount2(cfg, MNT_DETACH); } @@ -1057,15 +1077,17 @@ static int main_extroot(int argc, char **argv) } #ifdef UBIFS_EXTROOT - memset(fs_data, 0, sizeof(fs_data)); + /* ... but it also could be an UBI volume */ + memset(blkdev_path, 0, sizeof(blkdev_path)); libubi = libubi_open(); - find_block_ubi(libubi, "rootfs_data", fs_data, sizeof(fs_data)); + find_block_ubi(libubi, "rootfs_data", blkdev_path, sizeof(blkdev_path)); libubi_close(libubi); - if (fs_data[0]) { + if (blkdev_path[0]) { char cfg[] = "/tmp/ubifs_cfg"; + /* Mount volume and try extroot (using fstab from that vol) */ mkdir_p(cfg); - if (!mount(fs_data, cfg, "ubifs", MS_NOATIME, NULL)) { + if (!mount(blkdev_path, cfg, "ubifs", MS_NOATIME, NULL)) { err = mount_extroot(cfg); umount2(cfg, MNT_DETACH); } diff --git a/libfstools/extroot.c b/libfstools/extroot.c index 9a05c49..45cc3f5 100644 --- a/libfstools/extroot.c +++ b/libfstools/extroot.c @@ -24,6 +24,10 @@ char const *extroot_prefix = NULL; +/* + * This will execute "block extroot" and make use of mounted extroot or return + * an error. + */ int mount_extroot(void) { char ldlib_path[32]; diff --git a/mount_root.c b/mount_root.c index c1524a4..a8505fa 100644 --- a/mount_root.c +++ b/mount_root.c @@ -18,6 +18,10 @@ #include "libfstools/libfstools.h" #include "libfstools/volume.h" +/* + * Called in the early (PREINIT) stage, when we immediately need some writable + * filesystem. + */ static int start(int argc, char *argv[1]) { @@ -34,15 +38,26 @@ start(int argc, char *argv[1]) return 0; } + /* + * Before trying to mount and use "rootfs_data" let's check if there is + * extroot configured. Following call will handle reading config from + * the "rootfs_data" on its own. + */ extroot_prefix = ""; if (!mount_extroot()) { fprintf(stderr, "fs-state: switched to extroot\n"); return 0; } + /* There isn't extroot, so just try to mount "rootfs_data" */ switch (volume_identify(v)) { case FS_NONE: case FS_DEADCODE: + /* + * Filesystem isn't ready yet and we are in the preinit, so we + * can't afford waiting for it. Use tmpfs for now and handle it + * properly in the "done" call. + */ return ramoverlay(); case FS_JFFS2: @@ -67,6 +82,9 @@ stop(int argc, char *argv[1]) return 0; } +/* + * Called at the end of init, it can wait for filesystem if needed. + */ static int done(int argc, char *argv[1]) { -- 2.30.2