linux-btrfs.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: David Sterba <dsterba@suse.cz>
To: fdmanana@kernel.org
Cc: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH v2] Btrfs: fix race between send and deduplication that lead to failures and crashes
Date: Mon, 13 May 2019 17:56:07 +0200	[thread overview]
Message-ID: <20190513155607.GD3138@twin.jikos.cz> (raw)
In-Reply-To: <20190422154342.11873-1-fdmanana@kernel.org>

On Mon, Apr 22, 2019 at 04:43:42PM +0100, fdmanana@kernel.org wrote:
> +		btrfs_warn_rl(root_dst->fs_info,
> +"Can not deduplicate to root %llu while send operations are using it (%d in progress)",
> +			      root_dst->root_key.objectid,
> +			      root_dst->send_in_progress);

The test btrfs/187 stresses this code and the logs are flooded by the
messages, even ratelimited.

[ 7276.358431] btrfs_extent_same: 152 callbacks suppressed
[ 7276.358434] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7276.473264] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7276.476145] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7276.481035] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7276.509456] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7276.531005] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7276.654349] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7276.659043] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7276.664147] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7276.667872] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7281.386168] btrfs_extent_same: 151 callbacks suppressed
[ 7281.386171] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7281.391417] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7281.402340] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7281.424163] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7281.443574] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7281.559380] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7281.565187] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7281.569269] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7281.572955] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7281.603316] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7286.479641] btrfs_extent_same: 155 callbacks suppressed
[ 7286.479644] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7286.493800] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7286.497717] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7286.508728] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7286.541218] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7286.655025] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7286.659737] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7286.673313] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7286.678633] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7286.699049] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7291.485963] btrfs_extent_same: 155 callbacks suppressed
[ 7291.485966] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7291.504093] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7291.508731] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7291.524168] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7291.539922] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7291.656334] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7291.661194] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7291.663548] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7291.677950] BTRFS warning (device vdb): cannot deduplicate to root 263 while send operations are using it (1 in progress)
[ 7291.690344] BTRFS warning (device vdb): cannot deduplicate to root 260 while send operations are using it (2 in progress)
[ 7296.555685] btrfs_extent_same: 160 callbacks suppressed

I wonder if the test is rather artificail (and that's fine for the testing
purposes) or if the number of messages would repeat under normal conditions.

We don't need to print the message each time the dedup tries to acces a
snapshot under send, so keeping track if the message has been sent already
would be less intrusive and still provide the information.

  parent reply	other threads:[~2019-05-13 15:55 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-15  8:30 [PATCH] Btrfs: fix race between send and deduplication that lead to failures and crashes fdmanana
2019-04-17 14:11 ` David Sterba
2019-04-22 15:43 ` [PATCH v2] " fdmanana
2019-04-24 16:26   ` David Sterba
2019-05-13 15:56   ` David Sterba [this message]
2019-05-13 16:07     ` David Sterba
2019-05-13 16:18       ` Filipe Manana
2019-05-13 16:58         ` David Sterba
2019-05-13 17:05           ` Filipe Manana
2019-05-13 19:10             ` David Sterba
2019-05-13 22:06               ` David Sterba

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190513155607.GD3138@twin.jikos.cz \
    --to=dsterba@suse.cz \
    --cc=fdmanana@kernel.org \
    --cc=linux-btrfs@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).