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 168561B0413 for ; Sat, 9 Aug 2025 05:03:04 +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=1754715785; cv=none; b=gLi9vP4cChPKziiZP0AwyEbYE+yCgSMZJTBN/S3mrC4/slCbHZucJ9TJWrzszedDZwwO4ChLNoYdPeSsU5qNtqexLKmLeyz4LPsckZy8lI/45AJDg6+sEYfsfvtRUUbiNNeRrHHbjzmyyDldu5SqqOTHPtYlffkYaMqiLpB5/PY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754715785; c=relaxed/simple; bh=B64UkEYGZaiRzrSdXSRbjn8uTlmDOv1O4l8M279DYgc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oDeE8XfRnKZ4aatJzNCvVruOR5C+Jw1RTrAnO69KPpBba6ObClgUkqBJqTeGORa1xol6Jtu/fuUUAfDVBWj3Mpe3rzV19dNlUm5ehjwtOxmTqzoFzm/dVNtqNskUN0YMIIpUYHdjqYlZpyzUmktNh3hyRyUOMSIGhpTaVLTrvtc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pdjy7S1n; 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="Pdjy7S1n" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6674CC4CEE7; Sat, 9 Aug 2025 05:03:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1754715784; bh=B64UkEYGZaiRzrSdXSRbjn8uTlmDOv1O4l8M279DYgc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Pdjy7S1n2wU4ayh/7pd3lwB+jfZ5jsOx44r5iJMtMZWO7OSEqmoD+cRyfhoXHaL14 fGgV6YnPZ1F5j+kKWokFfpzSn82CZnpRAEWAD5c4H2S8YwmW1T+iZ6xHyEhkowfAYv ogmqlcfnAKULKXqdlWWmJokTDjEljlSTP5wzRXve3bPfElk0cbkrkExIb1TrHgqDKE FuuTak4Gnpin+M7rVBRM6giaKFj9kuC2k7e5sNBpY+IATkww4Ym0FeO9atvtO9MOR/ tA5L8wXeWWxItAFB0wl1kfPwblkHSov+NvBrf5iYPSAsTY76v3gssZQk6UqK4ZYbzX UFWEDh0tYq2fQ== From: Mike Snitzer To: Chuck Lever , Jeff Layton Cc: linux-nfs@vger.kernel.org Subject: [PATCH v6 4/7] NFSD: add io_cache_write controls to debugfs interface Date: Sat, 9 Aug 2025 01:02:54 -0400 Message-ID: <20250809050257.27355-5-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250809050257.27355-1-snitzer@kernel.org> References: <20250809050257.27355-1-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_write' to NFSD's debugfs interface so that: Any data written 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_write may be set by writing to: /sys/kernel/debug/nfsd/io_cache_write 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 WRITE payload must be aligned relative to the underlying block device's dma_alignment. Signed-off-by: Mike Snitzer --- fs/nfsd/debugfs.c | 43 +++++++++++++++++++++++++++++++++++++++++++ fs/nfsd/nfsd.h | 1 + fs/nfsd/vfs.c | 16 ++++++++++++++++ 3 files changed, 60 insertions(+) diff --git a/fs/nfsd/debugfs.c b/fs/nfsd/debugfs.c index 3cadd45868b48..8878c3519b30c 100644 --- a/fs/nfsd/debugfs.c +++ b/fs/nfsd/debugfs.c @@ -86,6 +86,46 @@ static int nfsd_io_cache_read_set(void *data, u64 val) DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_read_fops, nfsd_io_cache_read_get, nfsd_io_cache_read_set, "%llu\n"); +/* + * /sys/kernel/debug/nfsd/io_cache_write + * + * Contents: + * %1: NFS WRITE will use buffered IO + * %2: NFS WRITE will use dontcache (buffered IO w/ dropbehind) + * %3: NFS WRITE 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_write_get(void *data, u64 *val) +{ + *val = nfsd_io_cache_write; + return 0; +} + +static int nfsd_io_cache_write_set(void *data, u64 val) +{ + int ret = 0; + + switch (val) { + case NFSD_IO_BUFFERED: + case NFSD_IO_DONTCACHE: + case NFSD_IO_DIRECT: + nfsd_io_cache_write = val; + break; + default: + ret = -EINVAL; + break; + } + + return ret; +} + +DEFINE_DEBUGFS_ATTRIBUTE(nfsd_io_cache_write_fops, nfsd_io_cache_write_get, + nfsd_io_cache_write_set, "%llu\n"); + void nfsd_debugfs_exit(void) { debugfs_remove_recursive(nfsd_top_dir); @@ -101,4 +141,7 @@ void nfsd_debugfs_init(void) debugfs_create_file("io_cache_read", S_IWUSR | S_IRUGO, nfsd_top_dir, NULL, &nfsd_io_cache_read_fops); + + debugfs_create_file("io_cache_write", S_IWUSR | S_IRUGO, + nfsd_top_dir, NULL, &nfsd_io_cache_write_fops); } diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h index 6ef799405145f..fe935b4cda538 100644 --- a/fs/nfsd/nfsd.h +++ b/fs/nfsd/nfsd.h @@ -161,6 +161,7 @@ enum { }; extern u64 nfsd_io_cache_read __read_mostly; +extern u64 nfsd_io_cache_write __read_mostly; extern int nfsd_max_blksize; diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c index 8ea8b80097195..c340708fbab4d 100644 --- a/fs/nfsd/vfs.c +++ b/fs/nfsd/vfs.c @@ -50,6 +50,7 @@ bool nfsd_disable_splice_read __read_mostly; u64 nfsd_io_cache_read __read_mostly; +u64 nfsd_io_cache_write __read_mostly; /** * nfserrno - Map Linux errnos to NFS errnos @@ -1242,6 +1243,21 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, since = READ_ONCE(file->f_wb_err); if (verf) nfsd_copy_write_verifier(verf, nn); + + switch (nfsd_io_cache_write) { + case NFSD_IO_DIRECT: + /* direct I/O must be aligned to device logical sector size */ + if (nf->nf_dio_mem_align && nf->nf_dio_offset_align && + (((offset | *cnt) & (nf->nf_dio_offset_align-1)) == 0)) + kiocb.ki_flags |= IOCB_DIRECT; + break; + case NFSD_IO_DONTCACHE: + kiocb.ki_flags |= IOCB_DONTCACHE; + fallthrough; + case NFSD_IO_UNSPECIFIED: + case NFSD_IO_BUFFERED: + break; + } host_err = vfs_iocb_iter_write(file, &kiocb, &iter); if (host_err < 0) { commit_reset_write_verifier(nn, rqstp, host_err); -- 2.44.0