Monorepo for Aesthetic.Computer
aesthetic.computer
fix(native): loop unmount until /mnt stack is clean + tmpfs debug log
Post-mortem from lemon-martin's /mnt/install-debug.log showed the real
root cause of the BLKRRPART EBUSY loop: /mnt has a TWO-LEVEL mount
stack on the X1 Nano. init.sh found config.json on /dev/nvme0n1p1
first (USB enumeration slow) and mounted it at /mnt. Then ac-native's
setup_logging() mounted /dev/sda1 on top of /mnt (mount stacking).
/proc/mounts showed only one nvme entry (the underlying one) but the
TOPMOST fs at /mnt was sda1.
force_unmount_disk() grabbed the nvme target from /proc/mounts and
called umount2("/mnt", MNT_DETACH). But umount2 by PATH unmounts the
topmost mount at that path — which was sda1, not nvme. After one
unmount sda1 was gone but nvme was still the topmost at /mnt, still
referenced, still making BLKRRPART return EBUSY.
Fix:
1. force_unmount_disk now LOOPS (up to 16 iterations):
- Re-read /proc/mounts each iteration
- If any entry still matches /dev/<parent>, umount2 its target
- Continue until no matching entries remain
Each iteration pops one layer of the stack.
2. Log the full /proc/mounts (not just filtered) at the start and end
of force_unmount_disk so post-mortem can see the complete picture.
3. DLOG moved from /mnt/install-debug.log to /tmp/install-debug.log.
Tmpfs can't be affected by the nvme repartition, so the log
survives even if /mnt gets fully popped off the stack. After the
install attempt finishes (success or failure), copy the tmpfs log
back to /mnt/install-debug.log for next-boot post-mortem.
This should finally clear the BLKRRPART EBUSY on the X1 Nano and
similar laptops whose init.sh accidentally finds a stale config.json
on an internal ESP during slow USB enumeration.
+113
-36
+113
-36
fedac/native/src/ac-native.c
+113
-36
fedac/native/src/ac-native.c
···
784
784
static char install_fail_reason[256] = "";
785
785
static char install_fail_detail[256] = "";
786
786
787
-
// Unmount every entry in /proc/mounts whose SOURCE device matches /dev/<parent>
788
-
// or any of its partitions (/dev/<parent>p*, /dev/<parent>*). We use umount2
789
-
// with MNT_DETACH for the initial pass (lazy, always succeeds if the path is
790
-
// reachable) and log each action to the given log file. Returns the number of
791
-
// successful unmounts.
787
+
// Unmount every entry in /proc/mounts whose SOURCE device matches
788
+
// /dev/<parent> or any of its partitions. Loops until /proc/mounts no longer
789
+
// shows any matching entry — necessary for mount-stacked /mnt where the
790
+
// topmost fs might not be the one we want to unmount. Each iteration finds
791
+
// ONE matching target, umount2()'s it (MNT_DETACH pops the topmost mount at
792
+
// that path, which may or may not be the one we targeted — but after enough
793
+
// iterations the stack empties of any matching entries). Returns total
794
+
// successful umounts.
792
795
static int force_unmount_disk(const char *parent_blk, const char *dlog_path) {
793
796
int unmounted = 0;
794
-
FILE *mp = fopen("/proc/mounts", "r");
795
-
if (!mp) return 0;
796
-
// Collect targets first (don't unmount while iterating — /proc/mounts changes)
797
-
char targets[16][128];
798
-
int n_targets = 0;
799
-
char line[512];
800
-
while (n_targets < 16 && fgets(line, sizeof(line), mp)) {
801
-
// /proc/mounts format: source target fstype options ...
802
-
char src[128], tgt[128], fst[64];
803
-
if (sscanf(line, "%127s %127s %63s", src, tgt, fst) != 3) continue;
804
-
// Match /dev/<parent>, /dev/<parent>p1, /dev/<parent>1, etc.
805
-
if (strncmp(src, "/dev/", 5) != 0) continue;
806
-
const char *sbase = src + 5;
807
-
if (strncmp(sbase, parent_blk, strlen(parent_blk)) != 0) continue;
808
-
strncpy(targets[n_targets], tgt, sizeof(targets[0]) - 1);
809
-
targets[n_targets][sizeof(targets[0]) - 1] = 0;
810
-
n_targets++;
797
+
FILE *dl = dlog_path ? fopen(dlog_path, "a") : NULL;
798
+
if (dl) fprintf(dl, "--- force_unmount_disk(%s) start ---\n", parent_blk);
799
+
800
+
// First pass: log the full /proc/mounts so we can see the initial stack
801
+
{
802
+
FILE *mp = fopen("/proc/mounts", "r");
803
+
if (mp && dl) {
804
+
fprintf(dl, "--- initial /proc/mounts ---\n");
805
+
char line[512];
806
+
while (fgets(line, sizeof(line), mp)) fputs(line, dl);
807
+
fprintf(dl, "--- end /proc/mounts ---\n");
808
+
fclose(mp);
809
+
} else if (mp) {
810
+
fclose(mp);
811
+
}
812
+
}
813
+
814
+
const int MAX_ITER = 16; // belt-and-suspenders against mount-stack depth
815
+
for (int iter = 0; iter < MAX_ITER; iter++) {
816
+
// Find ONE target whose source starts with /dev/<parent>
817
+
char target[128] = "";
818
+
char source[128] = "";
819
+
FILE *mp = fopen("/proc/mounts", "r");
820
+
if (!mp) break;
821
+
char line[512];
822
+
while (fgets(line, sizeof(line), mp)) {
823
+
char src[128], tgt[128], fst[64];
824
+
if (sscanf(line, "%127s %127s %63s", src, tgt, fst) != 3) continue;
825
+
if (strncmp(src, "/dev/", 5) != 0) continue;
826
+
if (strncmp(src + 5, parent_blk, strlen(parent_blk)) != 0) continue;
827
+
strncpy(target, tgt, sizeof(target) - 1);
828
+
target[sizeof(target) - 1] = 0;
829
+
strncpy(source, src, sizeof(source) - 1);
830
+
source[sizeof(source) - 1] = 0;
831
+
break;
832
+
}
833
+
fclose(mp);
834
+
if (!target[0]) {
835
+
if (dl) fprintf(dl, "iter=%d: no matching mounts remain — done\n", iter);
836
+
break;
837
+
}
838
+
// Umount by path (MNT_DETACH pops the topmost mount, which may not be
839
+
// the one we scanned — that's ok, we loop and re-scan).
840
+
int r = umount2(target, MNT_DETACH);
841
+
if (dl) fprintf(dl, "iter=%d: umount2(%s, MNT_DETACH) src=%s = %d errno=%d\n",
842
+
iter, target, source, r, r < 0 ? errno : 0);
843
+
ac_log("[install] iter=%d umount2(%s) src=%s rc=%d errno=%d\n",
844
+
iter, target, source, r, r < 0 ? errno : 0);
845
+
if (r == 0) {
846
+
unmounted++;
847
+
} else {
848
+
// Try without MNT_DETACH as a fallback (plain umount).
849
+
r = umount2(target, 0);
850
+
if (dl) fprintf(dl, "iter=%d: umount2(%s, 0) fallback = %d errno=%d\n",
851
+
iter, target, r, r < 0 ? errno : 0);
852
+
if (r != 0) break;
853
+
unmounted++;
854
+
}
855
+
// Tiny yield so the kernel can finish detaching before we re-scan.
856
+
usleep(50000);
811
857
}
812
-
fclose(mp);
813
-
FILE *dl = dlog_path ? fopen(dlog_path, "a") : NULL;
814
-
if (dl) fprintf(dl, "--- force_unmount_disk(%s) found %d targets ---\n", parent_blk, n_targets);
815
-
for (int i = 0; i < n_targets; i++) {
816
-
// Try MNT_DETACH first (lazy — always works if target is valid).
817
-
int r = umount2(targets[i], MNT_DETACH);
818
-
if (dl) fprintf(dl, "umount2(%s, MNT_DETACH) = %d errno=%d\n",
819
-
targets[i], r, r < 0 ? errno : 0);
820
-
ac_log("[install] umount2(%s, MNT_DETACH) = %d errno=%d\n",
821
-
targets[i], r, r < 0 ? errno : 0);
822
-
if (r == 0) unmounted++;
858
+
859
+
if (dl) {
860
+
fprintf(dl, "--- force_unmount_disk(%s) total=%d ---\n", parent_blk, unmounted);
861
+
// Log post-unmount /proc/mounts so we can verify the stack is clean.
862
+
FILE *mp = fopen("/proc/mounts", "r");
863
+
if (mp) {
864
+
fprintf(dl, "--- post /proc/mounts ---\n");
865
+
char line[512];
866
+
while (fgets(line, sizeof(line), mp)) fputs(line, dl);
867
+
fprintf(dl, "--- end /proc/mounts ---\n");
868
+
fclose(mp);
869
+
}
870
+
fclose(dl);
823
871
}
824
-
if (dl) fclose(dl);
825
872
return unmounted;
826
873
}
827
874
···
1098
1145
// explicitly, then retry BLKRRPART with backoff.
1099
1146
umount("/tmp/hd");
1100
1147
umount2("/tmp/hd", MNT_DETACH);
1101
-
const char *DLOG = "/mnt/install-debug.log";
1148
+
// Write install-debug.log to TMPFS so it survives even
1149
+
// if the unmount loop pops the whole /mnt stack. We copy
1150
+
// it back to /mnt/install-debug.log at the end so the
1151
+
// USB has a post-mortem trace.
1152
+
const char *DLOG = "/tmp/install-debug.log";
1102
1153
// Fresh log per attempt
1103
1154
FILE *__dl = fopen(DLOG, "w");
1104
-
if (__dl) { fprintf(__dl, "=== install-debug starting ===\n"); fclose(__dl); }
1155
+
if (__dl) {
1156
+
fprintf(__dl, "=== install-debug starting ===\n");
1157
+
fprintf(__dl, "parent_blk=%s devpath=%s\n", parent_blk, devpath);
1158
+
fclose(__dl);
1159
+
}
1105
1160
// Unmount every mount currently referencing this disk.
1106
1161
int n_unmounted = force_unmount_disk(parent_blk, DLOG);
1107
1162
ac_log("[install] force_unmount_disk(%s) released %d mounts\n",
···
1325
1380
}
1326
1381
}
1327
1382
if (source_mounted_tmp) umount("/tmp/src");
1383
+
1384
+
// Copy the tmpfs install-debug.log back to /mnt so it survives the boot
1385
+
// session (tmpfs is wiped on reboot). Best effort — if /mnt got trashed
1386
+
// by the repartition attempt we simply skip. The log is most useful on
1387
+
// failure but we copy on success too so "what worked" is visible.
1388
+
{
1389
+
FILE *src = fopen("/tmp/install-debug.log", "rb");
1390
+
if (src) {
1391
+
FILE *dst = fopen("/mnt/install-debug.log", "wb");
1392
+
if (dst) {
1393
+
char buf[4096]; size_t n;
1394
+
while ((n = fread(buf, 1, sizeof(buf), src)) > 0)
1395
+
fwrite(buf, 1, n, dst);
1396
+
fflush(dst);
1397
+
fsync(fileno(dst));
1398
+
fclose(dst);
1399
+
ac_log("[install] copied /tmp/install-debug.log → /mnt/install-debug.log\n");
1400
+
}
1401
+
fclose(src);
1402
+
}
1403
+
}
1404
+
1328
1405
return installed;
1329
1406
}
1330
1407