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Date:   Wed, 11 Nov 2020 13:44:49 +0100
From:   Pavel Machek <pavel@ucw.cz>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Qu Wenruo <wqu@suse.com>, David Sterba <dsterba@suse.com>,
        Ben Hutchings <ben.hutchings@codethink.co.uk>
Subject: Re: [PATCH 4.19 19/71] btrfs: extent_io: add proper error handling
 to lock_extent_buffer_for_io()
Message-ID: <20201111124448.GA26508@amd>
References: <20201109125019.906191744@linuxfoundation.org>
 <20201109125020.811120362@linuxfoundation.org>
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Hi!

> Thankfully it's handled by the only caller, btree_write_cache_pages(),
> as later write_one_eb() call will trigger submit_one_bio().  So there
> shouldn't be any problem.

This explains there should not be any problem in _the
mainline_. AFAICT this talks about this code. Mainline version is:

 prev_eb =3D eb;
 ret =3D lock_extent_buffer_for_io(eb, &epd);
 if (!ret) {
 	free_extent_buffer(eb);
 	continue;
 } else if (ret < 0) {
 	done =3D 1;
 	free_extent_buffer(eb);
 	break;
 }

But 4.19 has:

 ret =3D lock_extent_buffer_for_io(eb, fs_info, &epd);
 if (!ret) {
  	free_extent_buffer(eb);
 	continue;
 }

IOW missing the code mentioned in the changelog. Is 0607eb1d452d4
prerequisite for this patch?

Best regards,
								Pavel

> +/*
> + * Lock eb pages and flush the bio if we can't the locks
> + *
> + * Return  0 if nothing went wrong
> + * Return >0 is same as 0, except bio is not submitted
> + * Return <0 if something went wrong, no page is locked
> + */

--=20
http://www.livejournal.com/~pavelmachek

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