Messages in this thread | | | Date | Fri, 2 Aug 2019 15:37:14 +0200 | From | Jan Kara <> | Subject | Re: [patch V2 6/7] fs/jbd2: Make state lock a spinlock |
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On Thu 01-08-19 20:12:11, Thomas Gleixner wrote: > On Thu, 1 Aug 2019, Jan Kara wrote: > > On Thu 01-08-19 03:01:32, Thomas Gleixner wrote: > > > As almost all functions which use this lock have a journal head pointer > > > readily available, it makes more sense to remove the lock helper inlines > > > and write out spin_*lock() at all call sites. > > > > > > > Just a heads up that I didn't miss this patch. Just it has some bugs and I > > figured that rather than explaining to you subtleties of jh lifetime it is > > easier to fix up the problems myself since you're probably not keen on > > becoming jbd2 developer ;)... which was more complex than I thought so I'm > > not completely done yet. Hopefuly tomorrow. > > I'm curious where I was too naive :)
Well, the most obvious where places where the result ended up being like
jbd2_journal_put_journal_head(jh); spin_unlock(&jh->state_lock);
That's possible use-after-free.
But there were also other more subtle places where jbd2_journal_put_journal_head() was not directly visible as it was hidden inside journal list handling functions such as __jbd2_journal_refile_buffer() or so. And these needed some more work.
Anyway, I'm now done fixing up the patch, doing some xfstests runs to verify things didn't break in any obvious way...
Honza -- Jan Kara <jack@suse.com> SUSE Labs, CR
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