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Date: Thu, 29 Aug 2019 21:22:36 -0400 From: "Theodore Y. Ts'o" <tytso@....edu> To: dann frazier <dann.frazier@...onical.com> Cc: Andreas Dilger <adilger@...ger.ca>, linux-ext4@...r.kernel.org, Jan Kara <jack@...e.com>, Colin King <colin.king@...onical.com>, Ryan Harper <ryan.harper@...onical.com> Subject: Re: ext4 fsck vs. kernel recovery policy (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
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