can't read superblock on /dev/xxxx sdc1 in my case

[alain maronani]

Upgrade ubuntu 18.04 to kernel 5.3.0-26-generic from kernel 5.0.0-37-generic using normal

apt update and apt upgrade

grub as generated by grub-mkconfig

menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-5bf582e8-676d-4c58-a555-f4623dcc70e3' {
 recordfail
 load_video
 gfxmode $linux_gfx_mode
 insmod gzio
 if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
 insmod part_gpt
 insmod ext2
 set root='hd1,gpt2'
 if [ x$feature_platform_search_hint = xy ]; then
   search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2 4d2c870a-9768-4667-b12a-33f74d31c9da
 else
   search --no-floppy --fs-uuid --set=root 4d2c870a-9768-4667-b12a-33f74d31c9da
 fi
        linux /vmlinuz-5.3.0-26-generic root=UUID=5bf582e8-676d-4c58-a555-f4623dcc70e3 ro rootflags=subvol=@ quiet splash $vt_handoff
 initrd /initrd.img-5.3.0-26-generic
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-5bf582e8-676d-4c58-a555-f4623dcc70e3' {
 menuentry 'Ubuntu, with Linux 5.3.0-26-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.3.0-26-generic-advanced-5bf582e8-676d-4c58-a555-f4623dcc70e3' {
  recordfail
  load_video
  gfxmode $linux_gfx_mode
  insmod gzio
  if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
  insmod part_gpt
  insmod ext2
  set root='hd1,gpt2'
  if [ x$feature_platform_search_hint = xy ]; then
    search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2 4d2c870a-9768-4667-b12a-33f74d31c9da
  else
    search --no-floppy --fs-uuid --set=root 4d2c870a-9768-4667-b12a-33f74d31c9da
  fi
  echo 'Loading Linux 5.3.0-26-generic ...'
         linux /vmlinuz-5.3.0-26-generic root=UUID=5bf582e8-676d-4c58-a555-f4623dcc70e3 ro rootflags=subvol=@ quiet splash $vt_handoff
  echo 'Loading initial ramdisk ...'
  initrd /initrd.img-5.3.0-26-generic
 }
 menuentry 'Ubuntu, with Linux 5.3.0-26-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.3.0-26-generic-recovery-5bf582e8-676d-4c58-a555-f4623dcc70e3' {
  recordfail
  load_video
  insmod gzio
  if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
  insmod part_gpt
  insmod ext2
  set root='hd1,gpt2'
  if [ x$feature_platform_search_hint = xy ]; then
    search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2 4d2c870a-9768-4667-b12a-33f74d31c9da
  else
    search --no-floppy --fs-uuid --set=root 4d2c870a-9768-4667-b12a-33f74d31c9da
  fi
  echo 'Loading Linux 5.3.0-26-generic ...'
         linux /vmlinuz-5.3.0-26-generic root=UUID=5bf582e8-676d-4c58-a555-f4623dcc70e3 ro recovery nomodeset rootflags=subvol=@
  echo 'Loading initial ramdisk ...'
  initrd /initrd.img-5.3.0-26-generic
 }
 menuentry 'Ubuntu, with Linux 5.0.0-37-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.0.0-37-generic-advanced-5bf582e8-676d-4c58-a555-f4623dcc70e3' {
  recordfail
  load_video
  gfxmode $linux_gfx_mode
  insmod gzio
  if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
  insmod part_gpt
  insmod ext2
  set root='hd1,gpt2'
  if [ x$feature_platform_search_hint = xy ]; then
    search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2 4d2c870a-9768-4667-b12a-33f74d31c9da
  else
    search --no-floppy --fs-uuid --set=root 4d2c870a-9768-4667-b12a-33f74d31c9da
  fi
  echo 'Loading Linux 5.0.0-37-generic ...'
         linux /vmlinuz-5.0.0-37-generic root=UUID=5bf582e8-676d-4c58-a555-f4623dcc70e3 ro rootflags=subvol=@ quiet splash $vt_handoff
  echo 'Loading initial ramdisk ...'
  initrd /initrd.img-5.0.0-37-generic
 }
 menuentry 'Ubuntu, with Linux 5.0.0-37-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.0.0-37-generic-recovery-5bf582e8-676d-4c58-a555-f4623dcc70e3' {
  recordfail
  load_video
  insmod gzio
  if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
  insmod part_gpt
  insmod ext2
  set root='hd1,gpt2'
  if [ x$feature_platform_search_hint = xy ]; then
    search --no-floppy --fs-uuid --set=root --hint-bios=hd1,gpt2 --hint-efi=hd1,gpt2 --hint-baremetal=ahci1,gpt2 4d2c870a-9768-4667-b12a-33f74d31c9da
  else
    search --no-floppy --fs-uuid --set=root 4d2c870a-9768-4667-b12a-33f74d31c9da
  fi
  echo 'Loading Linux 5.0.0-37-generic ...'
         linux /vmlinuz-5.0.0-37-generic root=UUID=5bf582e8-676d-4c58-a555-f4623dcc70e3 ro recovery nomodeset rootflags=subvol=@
  echo 'Loading initial ramdisk ...'
  initrd /initrd.img-5.0.0-37-generic
 }
}

/etc/fstab

# /etc/fstab: static file system information.
#
# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point> <type> <options> <dump> <pass>
# / was on /dev/sdb5 during installation
UUID=5bf582e8-676d-4c58-a555-f4623dcc70e3 / btrfs defaults,subvol=@ 0 1
# /boot was on /dev/sdb2 during installation
UUID=4d2c870a-9768-4667-b12a-33f74d31c9da /boot ext4 defaults 0 2
# /home was on /dev/sdb5 during installation
UUID=5bf582e8-676d-4c58-a555-f4623dcc70e3 /home btrfs defaults,subvol=@home 0 2
/boot/swapfile none swap sw 0 0

# user disk
UUID=08e9f1ce-81d5-4c46-828d-5bfff1a6dd5a /media/xxxx/big2tb btrfs defaults,noatime,space_cache,autodefrag,discard,compress=lzo
UUID=513657b4-58f5-4973-955f-f1b0638d7a50 /media/xxxx/b8 ext4 defaults,noatime

# SSD tweak: temporary directories as tmpfs

tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0
tmpfs /var/tmp tmpfs defaults,noatime,mode=1777 0 0
tmpfs /var/log tmpfs defaults,noatime,mode=1777 0 0

The system was not booting using the last kernel. In recovery also I was left with an unresponsive keyboard and not able to enter any options such as continue booting, enter root whatever.

After trial and errors I commented out the following entry in the fstab.

UUID=08e9f1ce-81d5-4c46-828d-5bfff1a6dd5a /media/xxxx/big2tb btrfs defaults,noatime,space_cache,autodefrag,discard,compress=lzo

The system was booting normally after using the last kernel.

I did try to mount the same disk after booting and got the message.

can't read superblock on /dev/sdc1.

The same disk works perfectly with Linux Lite.

I did a try with the last lubuntu 19.10 (booting from usb stick) and also got for the same message for the same disk

can't read superblock on /dev/sdc1.

[alain maronani (amaronani)]

I did run a btrfs check on a disk and I got

Checking filesystem on /dev/sdc1
UUID: 08e9f1ce-81d5-4c46-828d-5bfff1a6dd5a
checking extents
checking free space cache
checking fs roots
root 5 root dir 256 error
root 5 inode 256 errors 200, dir isize wrong
root 5 inode 18446744073709551605 errors 2001, no inode item, link count wrong
 unresolved ref dir 256 index 0 namelen 25 name System Volume Information filetype 2 errors 6, no dir index, no inode ref
ERROR: errors found in fs roots
found 406587551744 bytes used, error(s) found
total csum bytes: 395533372
total tree bytes: 1461895168
total fs tree bytes: 960806912
total extent tree bytes: 53084160
btree space waste bytes: 238263923
file data blocks allocated: 405125656576
 referenced 414054232064

The disk mount perfectly with linux lite (older kernel) and also mount with 5.0.0-37-generic

Do not work (system freeze) with 5.3.0-26-generic (do not work also with recent other linux distrib such as MX, POP OS (System76).

btrfs version is 4.15.1