From patchwork Fri Jun 9 19:46:13 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anna Schumaker X-Patchwork-Id: 13274338 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id B4EA8C7EE29 for ; Fri, 9 Jun 2023 19:46:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229709AbjFITqS (ORCPT ); Fri, 9 Jun 2023 15:46:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46028 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229517AbjFITqS (ORCPT ); Fri, 9 Jun 2023 15:46:18 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E871B35B1 for ; Fri, 9 Jun 2023 12:46:16 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7B9CF65B59 for ; Fri, 9 Jun 2023 19:46:16 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 945FBC433D2; Fri, 9 Jun 2023 19:46:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1686339975; bh=rWHKIeLp+DkUfZAEfHJ1g8fjTC73smlcD7Nwn1mUkKY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bDXa5vfgNqE2WpuGxhTzjm2XHEEmpNCbUf5SFep/9dpuE/TOJKFDioIM96n4tEc3g TtJLKaWNoijbWuIuQ8GXrmsf5nnp+ibYK7VAj4E4trZJy0zVB67lrSkXdvX39s4p1f laI69iYAIcwqCSlKHqQoVetVHDB+ZYenH5y7A0X4vpnMPvwrMnCb5HkE9NPfBK1mao PXudZ+z60MGTtK/1WtiqwlvVK72aPmt+OueHEKjRA7DLASAxdfMWYwmDGc2jHi2xZ3 4rkPLjEH7Z+4/FggLshi/lXx3Y6Ioco4xzMqKFLRHXvlOkHpgWCTkePxl9v2FOb4D/ cXmi43f6H9IDw== From: Anna Schumaker To: linux-nfs@vger.kernel.org, trond.myklebust@hammerspace.com Cc: anna@kernel.org Subject: [PATCH v2 3/3] NFSv4.2: Rework scratch handling for READ_PLUS (again) Date: Fri, 9 Jun 2023 15:46:13 -0400 Message-ID: <20230609194613.848590-3-anna@kernel.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230609194613.848590-1-anna@kernel.org> References: <20230609194613.848590-1-anna@kernel.org> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-nfs@vger.kernel.org From: Anna Schumaker I found that the read code might send multiple requests using the same nfs_pgio_header, but nfs4_proc_read_setup() is only called once. This is how we ended up occasionally double-freeing the scratch buffer, but also means we set a NULL pointer but non-zero length to the xdr scratch buffer. This results in an oops the first time decoding needs to copy something to scratch, which frequently happens when decoding READ_PLUS hole segments. I fix this by moving scratch handling into the pageio read code. I provide a function to allocate scratch space for decoding read replies, and free the scratch buffer when the nfs_pgio_header is freed. Krzysztof Kozlowski hit a bug a while ago with similar symptoms, and I'm hopeful that this patch fixes his issue. Reported-by: Krzysztof Kozlowski Fixes: fbd2a05f29a9 (NFSv4.2: Rework scratch handling for READ_PLUS) Signed-off-by: Anna Schumaker pick 7de817656b9b NFSD: Repeal and replace the READ_PLUS implementation --- fs/nfs/internal.h | 1 + fs/nfs/nfs42.h | 1 + fs/nfs/nfs42xdr.c | 2 +- fs/nfs/nfs4proc.c | 13 +------------ fs/nfs/read.c | 10 ++++++++++ 5 files changed, 14 insertions(+), 13 deletions(-) diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h index 3cc027d3bd58..1607c23f68d4 100644 --- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -489,6 +489,7 @@ extern const struct nfs_pgio_completion_ops nfs_async_read_completion_ops; extern void nfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode, bool force_mds, const struct nfs_pgio_completion_ops *compl_ops); +extern bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size); extern int nfs_read_add_folio(struct nfs_pageio_descriptor *pgio, struct nfs_open_context *ctx, struct folio *folio); diff --git a/fs/nfs/nfs42.h b/fs/nfs/nfs42.h index 0fe5aacbcfdf..b59876b01a1e 100644 --- a/fs/nfs/nfs42.h +++ b/fs/nfs/nfs42.h @@ -13,6 +13,7 @@ * more? Need to consider not to pre-alloc too much for a compound. */ #define PNFS_LAYOUTSTATS_MAXDEV (4) +#define READ_PLUS_SCRATCH_SIZE (16) /* nfs4.2proc.c */ #ifdef CONFIG_NFS_V4_2 diff --git a/fs/nfs/nfs42xdr.c b/fs/nfs/nfs42xdr.c index 75765382cc0e..20aa5e746497 100644 --- a/fs/nfs/nfs42xdr.c +++ b/fs/nfs/nfs42xdr.c @@ -1351,7 +1351,7 @@ static int nfs4_xdr_dec_read_plus(struct rpc_rqst *rqstp, struct compound_hdr hdr; int status; - xdr_set_scratch_buffer(xdr, res->scratch, sizeof(res->scratch)); + xdr_set_scratch_buffer(xdr, res->scratch, READ_PLUS_SCRATCH_SIZE); status = decode_compound_hdr(xdr, &hdr); if (status) diff --git a/fs/nfs/nfs4proc.c b/fs/nfs/nfs4proc.c index d3665390c4cb..73dc8a793ae9 100644 --- a/fs/nfs/nfs4proc.c +++ b/fs/nfs/nfs4proc.c @@ -5437,18 +5437,8 @@ static bool nfs4_read_plus_not_supported(struct rpc_task *task, return false; } -static inline void nfs4_read_plus_scratch_free(struct nfs_pgio_header *hdr) -{ - if (hdr->res.scratch) { - kfree(hdr->res.scratch); - hdr->res.scratch = NULL; - } -} - static int nfs4_read_done(struct rpc_task *task, struct nfs_pgio_header *hdr) { - nfs4_read_plus_scratch_free(hdr); - if (!nfs4_sequence_done(task, &hdr->res.seq_res)) return -EAGAIN; if (nfs4_read_stateid_changed(task, &hdr->args)) @@ -5468,8 +5458,7 @@ static bool nfs42_read_plus_support(struct nfs_pgio_header *hdr, /* Note: We don't use READ_PLUS with pNFS yet */ if (nfs_server_capable(hdr->inode, NFS_CAP_READ_PLUS) && !hdr->ds_clp) { msg->rpc_proc = &nfs4_procedures[NFSPROC4_CLNT_READ_PLUS]; - hdr->res.scratch = kmalloc(32, GFP_KERNEL); - return hdr->res.scratch != NULL; + return nfs_read_alloc_scratch(hdr, READ_PLUS_SCRATCH_SIZE); } return false; } diff --git a/fs/nfs/read.c b/fs/nfs/read.c index f71eeee67e20..7dc21a48e3e7 100644 --- a/fs/nfs/read.c +++ b/fs/nfs/read.c @@ -47,6 +47,8 @@ static struct nfs_pgio_header *nfs_readhdr_alloc(void) static void nfs_readhdr_free(struct nfs_pgio_header *rhdr) { + if (rhdr->res.scratch != NULL) + kfree(rhdr->res.scratch); kmem_cache_free(nfs_rdata_cachep, rhdr); } @@ -108,6 +110,14 @@ void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio) } EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds); +bool nfs_read_alloc_scratch(struct nfs_pgio_header *hdr, size_t size) +{ + WARN_ON(hdr->res.scratch != NULL); + hdr->res.scratch = kmalloc(size, GFP_KERNEL); + return hdr->res.scratch != NULL; +} +EXPORT_SYMBOL_GPL(nfs_read_alloc_scratch); + static void nfs_readpage_release(struct nfs_page *req, int error) { struct folio *folio = nfs_page_to_folio(req);