linux-ext4 - Re: [PATCH 20/22] jbd2: Make credit checking more strict

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Date:   Wed, 23 Oct 2019 15:30:29 +0200
From:   Jan Kara <jack@...e.cz>
To:     "Theodore Y. Ts'o" <tytso@....edu>
Cc:     Jan Kara <jack@...e.cz>, linux-ext4@...r.kernel.org
Subject: Re: [PATCH 20/22] jbd2: Make credit checking more strict

On Mon 21-10-19 18:29:59, Theodore Y. Ts'o wrote:
> On Fri, Oct 04, 2019 at 12:06:06AM +0200, Jan Kara wrote:
> > Make checking of available credits in jbd2_journal_dirty_metadata() more
> > strict. There should be always enough credits in the handle to write all
> > potential revoke descriptors. Also we warn in case there are not enough
> > credits since this is a bug in the filesystem.
> > 
> > Signed-off-by: Jan Kara <jack@...e.cz>
> 
> This is fine, but I wonder if we should also be returning an error in
> jbd2_journal_revoke() --- of course, one problem is ext4_forget() is
> getting called from ext4_free_blocks(), which currently doesn't return
> an error.  But we can capture the error return in __ext4_forget(), and
> at that point we can give a much more useful error message, since we
> can print the function caller and line number.

Yeah, that's a good point. I'll add a sanity check to jbd2_journal_revoke()
and then generate some error message in ext4.

> Feel free to add:
> 
> Reviewed-by: Theodore Ts'o <tytso@....edu>

Thanks!

								Honza
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR