From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E42AE15532C for ; Mon, 22 Apr 2024 16:40:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713804015; cv=none; b=Xu83IteaCDlckZhMsghmT0z3g6mYSkFfqLKLnCTMHuV+zTssCWOVgs4NATFuHr9IYdBDV+9+4p7zdscdn8j/sxX1+8B1mYnbEX4o8WWmHj1h+OnR4WNkSF/O2K4vy8RHgN0kcc38+qhNkgML+ZCp/sZNVLU6orqgVCKemYpS+9I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713804015; c=relaxed/simple; bh=HuOdS/o33+w9Mpc5xiCPIBPlI7L0jq+HfOPo1LzwERE=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=hQlt4WgtjZZV227Ff9fOChMMalzFRq0dnVj35lJKA2C1qb5PeTHP9H/MswXUihKtisDkdsp2e8S5wBFhB/DfIj+j4QysO2PWQHNnpEH7Lplnok9U90et4HVNnvKN56HU20diCm2XDEIpaIJQmip3yq8Agr60HrLLdrX2lH+v8kw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=cXguF37Q; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="cXguF37Q" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 85B3DC113CC; Mon, 22 Apr 2024 16:40:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1713804014; bh=HuOdS/o33+w9Mpc5xiCPIBPlI7L0jq+HfOPo1LzwERE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=cXguF37QaZvzlrbadISlF8DpJ2Uv1lhLIaZMqvFLftGbK8Adub5JAFI02r3PRu5HO ACd6lKVzM762mUF1bLSS2L/AqE5YQxlOh9lYCbAMomLRl5dsFNj+w2WcreMghfJbyI 5Ahjrkzc57M+S9TRJpcPgWoPa7Wg6Af+v4P6TF8iTAp2FkFwxIDIZnXXNN5fPEckO+ piBaQ8Hb9tPR+6xEktpdx+sQ25lKA8EBxutbc+7deFjU5pXCD900r75b85jeyC1oId caUZPey8tEdSJw014+0QkB4NJOc68Omam+dBxlz1c2DOkdmKbmelScjwVfViPKvCBH EIP1spafLFhlQ== From: cem@kernel.org To: linux-xfs@vger.kernel.org Cc: djwong@kernel.org, hch@lst.de Subject: [PATCH 44/67] xfs: add lock protection when remove perag from radix tree Date: Mon, 22 Apr 2024 18:26:06 +0200 Message-ID: <20240422163832.858420-46-cem@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240422163832.858420-2-cem@kernel.org> References: <20240422163832.858420-2-cem@kernel.org> Precedence: bulk X-Mailing-List: linux-xfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Long Li Source kernel commit: 07afd3173d0c6d24a47441839a835955ec6cf0d4 Take mp->m_perag_lock for deletions from the perag radix tree in xfs_initialize_perag to prevent racing with tagging operations. Lookups are fine - they are RCU protected so already deal with the tree changing shape underneath the lookup - but tagging operations require the tree to be stable while the tags are propagated back up to the root. Right now there's nothing stopping radix tree tagging from operating while a growfs operation is progress and adding/removing new entries into the radix tree. Hence we can have traversals that require a stable tree occurring at the same time we are removing unused entries from the radix tree which causes the shape of the tree to change. Likely this hasn't caused a problem in the past because we are only doing append addition and removal so the active AG part of the tree is not changing shape, but that doesn't mean it is safe. Just making the radix tree modifications serialise against each other is obviously correct. Signed-off-by: Long Li Reviewed-by: Christoph Hellwig Reviewed-by: "Darrick J. Wong" Signed-off-by: Chandan Babu R Signed-off-by: Carlos Maiolino --- libxfs/xfs_ag.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/libxfs/xfs_ag.c b/libxfs/xfs_ag.c index bdb8a08bb..1dbc01b97 100644 --- a/libxfs/xfs_ag.c +++ b/libxfs/xfs_ag.c @@ -422,13 +422,17 @@ xfs_initialize_perag( out_remove_pag: xfs_defer_drain_free(&pag->pag_intents_drain); + spin_lock(&mp->m_perag_lock); radix_tree_delete(&mp->m_perag_tree, index); + spin_unlock(&mp->m_perag_lock); out_free_pag: kmem_free(pag); out_unwind_new_pags: /* unwind any prior newly initialized pags */ for (index = first_initialised; index < agcount; index++) { + spin_lock(&mp->m_perag_lock); pag = radix_tree_delete(&mp->m_perag_tree, index); + spin_unlock(&mp->m_perag_lock); if (!pag) break; xfs_buf_hash_destroy(pag); -- 2.44.0