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 2631323185F for ; Mon, 14 Jul 2025 22:42:21 +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=1752532942; cv=none; b=PSZ/+mFn3b8e9FFVaRGC5mlZCOLB56x9TF48c90XD+YDfoQBPTAyQB6943cZkpRPGKvMxiwa4X6OoBZf7cGAlmC+k+WXXn5IId/jsZT6yZdCMs3hVLftCtnngNJ3NHg9EdxgIanu1f3358v2JD+jggwtBmrk3LLP69MEvnCUO34= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1752532942; c=relaxed/simple; bh=vXEsbrIXuwV4e3MQbzgEextK1GXhGvFlGtcYPnDkS0Q=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RhHNFbf9y2EeAvvJikhAtB0JuoCZTmSWqZU36Neetyk7RgtOM4GAOyNBdbKE+ESxTD3Ex4yTQqfcgA/RImIuKxv3FzIvdNJpj5ylz2F83NNh87RqhhpY34mJTIZdsZXZBCqA38gpOybc71hrQ4eq6jxHu5pV29wUDygygbLUggg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=QNmhu3x5; 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="QNmhu3x5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6989FC4CEED; Mon, 14 Jul 2025 22:42:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1752532941; bh=vXEsbrIXuwV4e3MQbzgEextK1GXhGvFlGtcYPnDkS0Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=QNmhu3x5wGGGF8wMQqvVyNgm9XHmgevKtjGYA9ywyaCusbuN8mGwO0RLEU4i6U8yz U6Rcyb+HU0u+ssb9293ivcdUzy2HrVwZ+MUeEaEEDZcrUA/Wn26vXjWqHzwoAJHety oz9dJu7km4FgBBkt3yYeK+Em2xyohcgUk5xjUCdclkBktD2ECnNem5kce6jaCoPWUv 9qki6wGIS4vW3Q8cfrouHC0vE0k5/XF9MhT4fC5XW9DZxHfubUYcxwpO/qqrjdIYm6 dDqIBtKCufuZAVYs9E0BRIcJzZi9bibj+gOEPkWDBXc1byhCatPhVj7f4wXaENYWjL Zqy8wkFF3hiRw== From: Mike Snitzer To: Chuck Lever , Jeff Layton Cc: linux-nfs@vger.kernel.org Subject: [PATCH v3 3/5] NFSD: add io_cache_read controls to debugfs interface Date: Mon, 14 Jul 2025 18:42:14 -0400 Message-ID: <20250714224216.14329-4-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250714224216.14329-1-snitzer@kernel.org> References: <20250714224216.14329-1-snitzer@kernel.org> Precedence: bulk X-Mailing-List: linux-nfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add 'io_cache_read' to NFSD's debugfs interface so that: Any data read by NFSD will either be: - cached using page cache (NFSD_IO_BUFFERED=1) - cached but removed from the page cache upon completion (NFSD_IO_DONTCACHE=2). - not cached (NFSD_IO_DIRECT=3) io_cache_read may be set by writing to: /sys/kernel/debug/nfsd/io_cache_read If NFSD_IO_DONTCACHE is specified using 2, FOP_DONTCACHE must be advertised as supported by the underlying filesystem (e.g. XFS), otherwise all IO flagged with RWF_DONTCACHE will fail with -EOPNOTSUPP. If NFSD_IO_DIRECT is specified using 3, the IO must be aligned relative to the underlying block device's logical_block_size. Also the memory buffer used to store the read must be aligned relative to the underlying block device's dma_alignment. Signed-off-by: Mike Snitzer --- fs/nfsd/debugfs.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++ fs/nfsd/nfsd.h | 9 ++++++++ fs/nfsd/vfs.c | 16 +++++++++++++ 3 files changed, 83 insertions(+) diff --git a/fs/nfsd/debugfs.c b/fs/nfsd/debugfs.c index 84b0c8b559dc..ad67ccba01ec 100644 --- a/fs/nfsd/debugfs.c +++ b/fs/nfsd/debugfs.c @@ -27,11 +27,66 @@ static int nfsd_dsr_get(void *data, u64 *val) static int nfsd_dsr_set(void *data, u64 val) { nfsd_disable_splice_read = (val > 0) ? true : false; + if (!nfsd_disable_splice_read) { + /* + * Cannot use NFSD_IO_DONTCACHE or NFSD_IO_DIRECT + * if splice_read is enabled. + */ + nfsd_io_cache_read = NFSD_IO_BUFFERED; + } return 0; } DEFINE_DEBUGFS_ATTRIBUTE(nfsd_dsr_fops, nfsd_dsr_get, nfsd_dsr_set, "%llu\n"); +/* + * /sys/kernel/debug/nfsd/io_cache_read + * + * Contents: + * %1: NFS READ will use buffered IO + * %2: NFS READ will use dontcache (buffered IO w/ dropbehind) + * %3: NFS READ will use direct IO + * + * The default value of this setting is zero (UNSPECIFIED). + * This setting takes immediate effect for all NFS versions, + * all exports, and in all NFSD net namespaces. + */ + +static int nfsd_io_cache_read_get(void *data, u64 *val) +{ + *val = nfsd_io_cache_read; + return 0; +} + +static int nfsd_io_cache_read_set(void *data, u64 val) +{ + int ret = 0; + + switch (val) { + case NFSD_IO_BUFFERED: + nfsd_io_cache_read = NFSD_IO_BUFFERED; + break; + case NFSD_IO_DONTCACHE: + case NFSD_IO_DIRECT: + /* + * Must disable splice_read when enabling + * NFSD_IO_DONTCACHE or NFSD_IO_DIRECT. + */ + nfsd_disable_splice_read = true; + nfsd_io_cache_read = val; + break; + default: + nfsd_io_cache_read = NFSD_IO_UNSPECIFIED; + ret = -EINVAL; + break; + } + + return ret; +} + +DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_read_fops, nfsd_io_cache_read_get, + nfsd_io_cache_read_set, "%llu\n"); + void nfsd_debugfs_exit(void) { debugfs_remove_recursive(nfsd_top_dir); @@ -44,4 +99,7 @@ void nfsd_debugfs_init(void) debugfs_create_file("disable-splice-read", S_IWUSR | S_IRUGO, nfsd_top_dir, NULL, &nfsd_dsr_fops); + + debugfs_create_file("io_cache_read", S_IWUSR | S_IRUGO, + nfsd_top_dir, NULL, &nfsd_io_cache_read_fops); } diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h index 1cd0bed57bc2..6ef799405145 100644 --- a/fs/nfsd/nfsd.h +++ b/fs/nfsd/nfsd.h @@ -153,6 +153,15 @@ static inline void nfsd_debugfs_exit(void) {} extern bool nfsd_disable_splice_read __read_mostly; +enum { + NFSD_IO_UNSPECIFIED = 0, + NFSD_IO_BUFFERED, + NFSD_IO_DONTCACHE, + NFSD_IO_DIRECT, +}; + +extern u64 nfsd_io_cache_read __read_mostly; + extern int nfsd_max_blksize; static inline int nfsd_v4client(struct svc_rqst *rq) diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 845c212ad10b..2fb8bac358e6 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -49,6 +49,7 @@ #define NFSDDBG_FACILITY NFSDDBG_FILEOP bool nfsd_disable_splice_read __read_mostly; +u64 nfsd_io_cache_read __read_mostly; /** * nfserrno - Map Linux errnos to NFS errnos @@ -1107,6 +1108,21 @@ __be32 nfsd_iter_read(struct svc_rqst *rqstp, struct svc_fh *fhp, trace_nfsd_read_vector(rqstp, fhp, offset, *count); iov_iter_bvec(&iter, ITER_DEST, rqstp->rq_bvec, v, *count); + + switch (nsfd_io_cache_read) { + case NFSD_IO_DIRECT: + if (nf->nf_dio_mem_align && nf->nf_dio_read_offset_align && + iov_iter_is_aligned(&iter, nf->nf_dio_mem_align - 1, + nf->nf_dio_read_offset_align - 1)) + kiocb.ki_flags = IOCB_DIRECT; + break; + case NFSD_IO_DONTCACHE: + kiocb.ki_flags = IOCB_DONTCACHE; + break; + case NFSD_IO_BUFFERED: + break; + } + host_err = vfs_iocb_iter_read(file, &kiocb, &iter); return nfsd_finish_read(rqstp, fhp, file, offset, count, eof, host_err); } -- 2.44.0