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 1F6B82ED848 for ; Thu, 24 Jul 2025 19:31:09 +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=1753385470; cv=none; b=kFvqCdJkA9qlEz9TawI2PRpCiAs8vDm/3jKdhf/z1pt3wxhrSYq0mFGK6hb9oanrEC2IMhatnudU5LqyZCHlr4uH57Bk13C0qsoc7Q9XSYxMxBWMeahXOsg03nuRusMwlrtQCL3NkZDAoxXANCcW1gWUG9vTG4dHNXsCNvKEwH8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1753385470; c=relaxed/simple; bh=sDLH9efdm1kTt3trWi5YJW6bOzUH3Rj9+wxztaHAXvQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=d481w2D9zLdBhjlIoP95iMyW3Vvpy4IqyEVbHP2QA8cwoAVXQvzBYeDZSp/D3+b0MF+gzfj76MLuX+wVLh2T7Tk4SIZvp2Xj7SviqOCFX9t4Ao8wOLOXE8inUnE2ftlHzdTXmd/UcA9dZmMQMyovRB5lyPDk17qDW8nR0fZZt/k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Ko6Pdua2; 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="Ko6Pdua2" Received: by smtp.kernel.org (Postfix) with ESMTPSA id EEEFEC4CEED; Thu, 24 Jul 2025 19:31:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1753385469; bh=sDLH9efdm1kTt3trWi5YJW6bOzUH3Rj9+wxztaHAXvQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ko6Pdua27j4eTxJrgZ4Cgur2gJvIlybZPYCMlheOjYl0Wo+Nc1rn7b2doUgnip6Gs EOVR+NGco0EEijCGkjGk6MbRrzFoz1E4SGJaHwSed3fjOFlno85568N2vuy1df0+TJ W3vVbs3opdg80jnOkPDJgIf6So+I3242ew9Iw3RpRsvkYtKBsvQ4fbJciabitPECBO tP7+NaOdsZOoX2K2TGThD/3dDOJDT/FgM9GhPXAPppEL2Vq02ywHAoEC8M9smUeNHd LYduyGNPukRLPKgy1X0Hr16O1gJt8zH5pcSssUKo6OUav4TjXthxKNuKEUCxRZE0KK p6QYso496ni4w== From: Mike Snitzer To: Chuck Lever , Jeff Layton , Trond Myklebust , Anna Schumaker Cc: linux-nfs@vger.kernel.org Subject: [PATCH v5 04/13] NFSD: add io_cache_write controls to debugfs interface Date: Thu, 24 Jul 2025 15:30:53 -0400 Message-ID: <20250724193102.65111-5-snitzer@kernel.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20250724193102.65111-1-snitzer@kernel.org> References: <20250724193102.65111-1-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 | 44 ++++++++++++++++++++++++++++++++++++++++++++ fs/nfsd/nfsd.h | 1 + fs/nfsd/vfs.c | 18 ++++++++++++++++++ 3 files changed, 63 insertions(+) diff --git a/fs/nfsd/debugfs.c b/fs/nfsd/debugfs.c index c07f71d4e84f..872de65f0e9a 100644 --- a/fs/nfsd/debugfs.c +++ b/fs/nfsd/debugfs.c @@ -87,6 +87,47 @@ 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: + nfsd_io_cache_write = NFSD_IO_UNSPECIFIED; + 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); @@ -102,4 +143,7 @@ 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 6ef799405145..fe935b4cda53 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 145f6d635ac7..a7a587736a22 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 @@ -1238,6 +1239,23 @@ nfsd_vfs_write(struct svc_rqst *rqstp, struct svc_fh *fhp, nvecs = xdr_buf_to_bvec(rqstp->rq_bvec, rqstp->rq_maxpages, payload); iov_iter_bvec(&iter, ITER_SOURCE, rqstp->rq_bvec, nvecs, *cnt); + + 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) && + iov_iter_is_aligned(&iter, nf->nf_dio_mem_align - 1, + nf->nf_dio_offset_align - 1)) + kiocb.ki_flags = IOCB_DIRECT; + break; + case NFSD_IO_DONTCACHE: + kiocb.ki_flags = IOCB_DONTCACHE; + break; + case NFSD_IO_BUFFERED: + break; + } + since = READ_ONCE(file->f_wb_err); if (verf) nfsd_copy_write_verifier(verf, nn); -- 2.44.0