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 5B247292B44 for ; Wed, 3 Sep 2025 20:51:28 +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=1756932688; cv=none; b=DX2zBVrjKHrsrYH0Xk8nsrxSRcczFoLODRSRczP91iM8wploaOHkoiw9pBa5La8SiCsJZ6tYI1jxSaTeqIvFmJ2s+/F2qHfoyptdXhK6c/WFpBCdR+nk/7+kwgB7WhjFxL8f3HV2dAX9UaakQKofDv4ik45e2U/6OrcGtbViqWw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756932688; c=relaxed/simple; bh=qC95KkQufc8ofeKhe163gS0DeiP6XtpnVFCCKfGL1hs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=ZVY8p/rJMcpscZYwobzvLR+IpwAGMK84diQdQCsOwVkBsrQ6lf5cD3cRFT8NlUiUX41Hf8uvnkyaWR6kG6y8bzDPuzXuTw0TxwZWKJxqSiIG/7cARhNMP03ENdNoqgcZP3JUnyJ0/j82f1+PL/VIGsrYC2kERd2bSYHeHTY1Z4M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=KnisvmQN; 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="KnisvmQN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 01794C4CEE7; Wed, 3 Sep 2025 20:51:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1756932688; bh=qC95KkQufc8ofeKhe163gS0DeiP6XtpnVFCCKfGL1hs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=KnisvmQNdsb8sHPjVyhWNPrFF2YkuxAR73T/fMIDnHoJTgc5kkWgf6jxQmvU4+jDd 4LlklswrNxbmsiSeWDknZG5iCtJTrR7FnaCGf7K5o3TRiOzXP2jveTQC3tbWICbFYA vxOEWbcdh8gJiQpIg3pFk2MUXs8752Tnz2jiCFHaJtdIKUv9NXZKFYnDqU+LFKRnkT K/hfitEeg06ATI/c3aTURm8NDrIoefFyvOzkefQn/z5MtIgqt3vkKsijW2tDCqkben 1YUrZxKXHjMBMHw0tck6r2kOaDS4wlmZMt/XJ7+AXJuLgSRIP2drNpQtCZMLOJrARG ilb88pxioAgpQ== From: Mike Snitzer To: Chuck Lever , Jeff Layton Cc: linux-nfs@vger.kernel.org Subject: [PATCH v9 4/9] NFSD: add io_cache_write controls to debugfs interface Date: Wed, 3 Sep 2025 16:51:16 -0400 Message-ID: <20250903205121.41380-5-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250903205121.41380-1-snitzer@kernel.org> References: <20250903205121.41380-1-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=0) - cached but removed from the page cache upon completion (NFSD_IO_DONTCACHE=1). - not cached (NFSD_IO_DIRECT=2) io_cache_write may be set by writing to: /sys/kernel/debug/nfsd/io_cache_write The default value for io_cache_write reflects NFSD's current default IO mode (NFSD_IO_BUFFERED=0). If NFSD_IO_DONTCACHE is specified using 1, 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 2, 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 | 42 ++++++++++++++++++++++++++++++++++++++++++ fs/nfsd/nfsd.h | 1 + fs/nfsd/vfs.c | 15 +++++++++++++++ 3 files changed, 58 insertions(+) diff --git a/fs/nfsd/debugfs.c b/fs/nfsd/debugfs.c index dd1dc28a53784..173032a04cdec 100644 --- a/fs/nfsd/debugfs.c +++ b/fs/nfsd/debugfs.c @@ -85,6 +85,45 @@ 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: + * %0: NFS WRITE will use buffered IO + * %1: NFS WRITE will use dontcache (buffered IO w/ dropbehind) + * %2: NFS WRITE will use direct IO + * + * 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); @@ -100,4 +139,7 @@ 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 41cb7c7feff3e..c491eb258ecd3 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 21441745df69a..358d10a0665f6 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 = NFSD_IO_BUFFERED; +u64 nfsd_io_cache_write __read_mostly = NFSD_IO_BUFFERED; /** * nfserrno - Map Linux errnos to NFS errnos @@ -1241,6 +1242,20 @@ 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; + break; + 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