On Sun, 19 Aug 2018, Mikulas Patocka wrote:
On Sun, 19 Aug 2018, Axel Beckert wrote:
Control: tag -1 + moreinfo
,Hi Mikulas
Mikulas Patocka wrote:
Package: aptitude
^^^^^^^^
* What led up to the situation?
apt doesn't call fsync when writing the file extended_states - so that if
^^^
If you strace aptitude, you can see that it writes the file
^^^^^^^^
I had my file extended_states corrupted when the system crashed while
doing unattended upgrades.
^^^^^^^^^^^^^^^^^^^
apt should call fsync before closing the file handle
^^^
You've mentioned three different package managing tools: apt, aptitude
and unattended-upgrades.
Since you've straced aptitude, I assume you meant aptitude where you
wrote apt. But then again unattended-upgrades uses apt, not aptitude.
Please clarify!
Regards, Axel
All of the apt tools should use fsync (because the machine may crash when the
user is using any of them).
In my case, unattended-upgrades corrupted the file extended_states when the
machine crashed, but unattended-upgrades will not write the file if there are
no upgrades being done, so stracing it doesn't show the bug.
Mikulas
I've straced unattended-upgrade while doing an upgrade and it also doesn't use
fsync, just like aptitude:
1858 openat(AT_FDCWD, "/var/lib/apt/extended_states.lzL2ec",
O_RDWR|O_CREAT|O_EXCL, 0600) = 6
1858 umask(000) = 022
1858 umask(022) = 000
1858 fchmod(6, 0644) = 0
1858 fcntl(6, F_SETFD, FD_CLOEXEC) = 0
1858 write(6, "Package: qemu-system-mips\n", 26) = 26
1858 write(6, "Status: install ok installed\n", 29) = 29
1858 write(6, "Priority: optional\n", 19) = 19
1858 write(6, "Section: otherosfs\n", 19) = 19
1858 write(6, "Installed-Size: 38108\n", 22) = 22
1858 write(6, "Maintainer: Debian QEMU Team
<pkg-qemu-de...@lists.alioth.debian.org>\n", 70) = 70
1858 write(6, "Architecture: arm64\n", 20) = 20
1858 write(6, "Multi-Arch: foreign\n", 20) = 20
....
1858 write(6, "Package: base-files\n", 20) = 20
1858 write(6, "Architecture: arm64\n", 20) = 20
1858 write(6, "Auto-Installed: 1\n", 18) = 18
1858 write(6, "\n", 1) = 1
1858 write(6, "Package: libvirt-daemon\n", 24) = 24
1858 write(6, "Architecture: arm64\n", 20) = 20
1858 write(6, "Auto-Installed: 1\n", 18) = 18
1858 write(6, "\n", 1) = 1
1858 close(6) = 0
1858 renameat(AT_FDCWD, "/var/lib/apt/extended_states.lzL2ec", AT_FDCWD,
"/var/lib/apt/extended_states") = 0
1858 fchmodat(AT_FDCWD, "/var/lib/apt/extended_states", 0644) = 0
1858 close(5) = 0
Mikulas
