From nobody Tue Dec 16 07:32:59 2025 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B76E7182A79 for ; Wed, 17 Jul 2024 17:22:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721236954; cv=none; b=A3yjQvQBdxEKM3w88piBLRlnSg9HC4GKIVcQRB3PQ3b7/MZBMnsSQ/IwmQljcMp0Ps4WyFI7E4I23b+DSfEoz0sJuk/v7Mtatghf9Lznb5yl6++jciDDO9l35/zhrZLjSntju00DxvXimYWk8d2+DGnvH405rqG3lBJTPErsPTY= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1721236954; c=relaxed/simple; bh=w1NPe9WcILqvBMR79gBUkgBg/mpRAjlzexIbZk8XiQw=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=jX907CUKfqJzQFaTCvZcuRqFvQI0KeHO4CUcBW9FNnXaCs1Jggm4TB4YMtvXtcFC26pqF9D8KiyxRxg2NNRJfsD4h9yzmUrznBTTXWeoDsPcJKk2ZAZcUXJJj/a/2e+1lX63QYajzOkUv2EJQFsuDGGy+toNA2QEgN9HJIQXakI= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=O6zNBnn4; arc=none smtp.client-ip=91.218.175.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="O6zNBnn4" X-Envelope-To: tytso@mit.edu DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1721236948; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=K106XqbcYfH8ci1Y+fSU8zpOaaksHSItrgPnvgG054c=; b=O6zNBnn42JkMAoaTew959hYqfNDCCnwiSf+sFN4v67msWI0CF3PKnjg5U94CyApPmaNA0C fTXsE1iPfiSEZ8gfR8FHs1vvK4l+8GT/UawNrDvfQynAILAyZEga2gINsHNXXqfLDkC5Vb Ar5tljMKDzk890b0zEzDK4Zotija7B0= X-Envelope-To: adilger@dilger.ca X-Envelope-To: jack@suse.cz X-Envelope-To: harshadshirwadkar@gmail.com X-Envelope-To: linux-ext4@vger.kernel.org X-Envelope-To: linux-kernel@vger.kernel.org X-Envelope-To: luis.henriques@linux.dev X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: "Luis Henriques (SUSE)" To: Theodore Ts'o , Andreas Dilger , Jan Kara , Harshad Shirwadkar Cc: linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, "Luis Henriques (SUSE)" Subject: [PATCH v5] ext4: fix fast commit inode enqueueing during a full journal commit Date: Wed, 17 Jul 2024 18:22:20 +0100 Message-ID: <20240717172220.14201-1-luis.henriques@linux.dev> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset="utf-8" When a full journal commit is on-going, any fast commit has to be enqueued into a different queue: FC_Q_STAGING instead of FC_Q_MAIN. This enqueueing is done only once, i.e. if an inode is already queued in a previous fast commit entry it won't be enqueued again. However, if a full commit starts _after_ the inode is enqueued into FC_Q_MAIN, the next fast commit needs to be done into FC_Q_STAGING. And this is not being done in function ext4_fc_track_template(). This patch fixes the issue by re-enqueuing an inode into the STAGING queue during the fast commit clean-up callback when doing a full commit. However, to prevent a race with a fast-commit, the clean-up callback has to be called with the journal locked. This bug was found using fstest generic/047. This test creates several 32k bytes files, sync'ing each of them after it's creation, and then shutting down the filesystem. Some data may be loss in this operation; for example a file may have it's size truncated to zero. Suggested-by: Jan Kara Signed-off-by: Luis Henriques (SUSE) Reviewed-by: Jan Kara --- Hi! And here's another attempt to fix this bug. The most significant change is that now it doesn't assume a 'special' meaning for a tid of '0'. Which is a wrong assumption as Jan has shown. I've also added a Suggested-by: tag, although Jan pretty much owns this patch -- I have simply tested it and sent it out! fs/ext4/fast_commit.c | 15 ++++++++++++++- fs/jbd2/journal.c | 2 +- 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/fs/ext4/fast_commit.c b/fs/ext4/fast_commit.c index 3926a05eceee..df71fd5b1fed 100644 --- a/fs/ext4/fast_commit.c +++ b/fs/ext4/fast_commit.c @@ -1288,8 +1288,21 @@ static void ext4_fc_cleanup(journal_t *journal, int = full, tid_t tid) list_del_init(&iter->i_fc_list); ext4_clear_inode_state(&iter->vfs_inode, EXT4_STATE_FC_COMMITTING); - if (tid_geq(tid, iter->i_sync_tid)) + if (tid_geq(tid, iter->i_sync_tid)) { ext4_fc_reset_inode(&iter->vfs_inode); + } else if (full) { + /* + * We are called after a full commit, inode has been + * modified while the commit was running. Re-enqueue + * the inode into STAGING, which will then be splice + * back into MAIN. This cannot happen during + * fastcommit because the journal is locked all the + * time in that case (and tid doesn't increase so + * tid check above isn't reliable). + */ + list_add_tail(&EXT4_I(&iter->vfs_inode)->i_fc_list, + &sbi->s_fc_q[FC_Q_STAGING]); + } /* Make sure EXT4_STATE_FC_COMMITTING bit is clear */ smp_mb(); #if (BITS_PER_LONG < 64) diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 1ebf2393bfb7..291a431f8aaf 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -740,9 +740,9 @@ EXPORT_SYMBOL(jbd2_fc_begin_commit); */ static int __jbd2_fc_end_commit(journal_t *journal, tid_t tid, bool fallba= ck) { - jbd2_journal_unlock_updates(journal); if (journal->j_fc_cleanup_callback) journal->j_fc_cleanup_callback(journal, 0, tid); + jbd2_journal_unlock_updates(journal); write_lock(&journal->j_state_lock); journal->j_flags &=3D ~JBD2_FAST_COMMIT_ONGOING; if (fallback)