Hi Ted,
On Mon, Jul 1, 2019 at 3:56 PM Theodore Ts'o <tytso@xxxxxxx> wrote:
> On Mon, Jul 01, 2019 at 02:43:14PM +0200, Geert Uytterhoeven wrote:
> > Despite this fix having been applied upstream, the kernel prints from
> > time to time:
> >
> > EXT4-fs (sda1): error count since last fsck: 5
> > EXT4-fs (sda1): initial error at time 1557931133:
> > ext4_get_branch:171: inode 1980: block 27550
> > EXT4-fs (sda1): last error at time 1558114349:
> > ext4_get_branch:171: inode 1980: block 27550
> >
> > This happens even after a manual run of "e2fsck -f" (while it's mounted
> > RO), which reports a clean file system.
>
> What's happening is this. When the kernel detects a corruption, newer
> kernels will set these superblock fields:
>
> __le32 s_error_count; /* number of fs errors */
> __le32 s_first_error_time; /* first time an error happened */
> __le32 s_first_error_ino; /* inode involved in first error */
> __le64 s_first_error_block; /* block involved of first error */
> __u8 s_first_error_func[32] __nonstring; /* function where the error happened */
> __le32 s_first_error_line; /* line number where error happened */
> __le32 s_last_error_time; /* most recent time of an error */
> __le32 s_last_error_ino; /* inode involved in last error */
> __le32 s_last_error_line; /* line number where error happened */
> __le64 s_last_error_block; /* block involved of last error */
> __u8 s_last_error_func[32] __nonstring; /* function where the error happened */
>
> When newer versions of e2fsck *fix* the corruption, it will clear
> these fields. It's basically a safety check because *way* too many
> ext4 users run with errors=continue (aka, "don't worry, be happy"
> mode), and so this is a poke in the system logs that the file system
> is corrupted, and they, really, *REALLY* should fix it before they
> lose (more) data.
Thanks for the explanation, much appreciated!
> > The inode and block numbers match the numbers printed due to the
> > previous bug.
>
> You can also see when the last file system error was detected via:
>
> % date -d @1558114349
> Fri 17 May 2019 01:32:29 PM EDT
Good. So no new errors detected after the fix.
> > Do you have an idea what's wrong?
> > Note that I run a very old version of e2fsck (from a decade ago).
>
> ... and that's the problem. If you're going to be using newer
> versions of the kernel, you really should be using newer versions of
> e2fsprogs.
>
> There have been a lot of bug fixes in the last 10 years, and some of
> them can be data corruption bugs....
Yeah, one day I'll have to change the winning horse...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
