From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: dann frazier <dann.frazier@canonical.com>
Cc: Andreas Dilger <adilger@dilger.ca>,
linux-ext4@vger.kernel.org, Jan Kara <jack@suse.com>,
Colin King <colin.king@canonical.com>,
Ryan Harper <ryan.harper@canonical.com>
Subject: Re: ext4 fsck vs. kernel recovery policy
Date: Thu, 29 Aug 2019 21:22:36 -0400 [thread overview]
Message-ID: <20190830012236.GC10779@mit.edu> (raw)
In-Reply-To: <20190829225348.GA13045@xps13.dannf>
(Changing the cc from linux-fsdevel to linux-ext4.)
On Thu, Aug 29, 2019 at 04:53:48PM -0600, dann frazier wrote:
> JBD2: Invalid checksum recovering data block 517634 in log
>
> So is it correct to say that the checksum errors were identifying
> filesystem correctness issues, and therefore e2fsck was needed to
> correct them?
That's correct. More precisely, checksum errors for journal blocks
are presumed to mean that file system might be corrupt, so a full
e2fsck check was needed to make sure the file system was consistent.
> You're probably right - this issue is very easy to reproduce w/
> data=journal,journal_checksum. I was never able to reproduce it
> otherwise.
I've looked at the data block numbers that you've reported, and they
come from a journald file. The problem is with data=journal +
journal_checksum + mmap. Unfortunately, we don't handle that
combination correctly at the moment.
The fix is going to have to involve fixing __ext4_journalled_writepage()
to call set_page_writeback() before it unlocks the page, adding a list of
pages under data=journalled writeback which is attached to the
transaction handle, have the jbd2 commit hook call end_page_writeback()
on all of these pages, and then in the places where ext4 calls
wait_for_stable_page() or grab_cache_page_write_begin(),
we need to add:
if (ext4_should_journal_data(inode))
wait_on_page_writeback(page);
It's all relatively straightforward except for the part where we have to
attach a list of pages to the currently running transaction. That
will require adding some plumbing into the jbd2 layer.
Dann, any interest in trying to code this fix?
- Ted
next parent reply other threads:[~2019-08-30 1:22 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CALdTtnuRqgZ=By1JQ0yJJYczUPxxYCWPkAey4BjBkmj77q7aaA@mail.gmail.com>
[not found] ` <5FEB4E1B-B21B-418D-801D-81FF7C6C069F@dilger.ca>
[not found] ` <20190829225348.GA13045@xps13.dannf>
2019-08-30 1:22 ` Theodore Y. Ts'o [this message]
2019-09-04 14:58 ` ext4 fsck vs. kernel recovery policy dann frazier
2019-12-21 20:26 ` mfo
2019-12-21 20:26 ` [RFC 1/1] ext4: set page writeback on journalled writepage mfo
2020-01-27 11:34 ` Re: ext4 fsck vs. kernel recovery policy Mauricio Faria de Oliveira
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