From:   schumaker.anna@gmail.com
To:     Trond.Myklebust@hammerspace.com, linux-nfs@vger.kernel.org
Cc:     Anna.Schumaker@Netapp.com
Subject: [PATCH 6/6] NFS: Add a mount option for READ_PLUS
Date:   Fri, 22 Feb 2019 16:59:18 -0500
Message-Id: <20190222215918.20647-7-Anna.Schumaker@Netapp.com>
In-Reply-To: <20190222215918.20647-1-Anna.Schumaker@Netapp.com>
References: <20190222215918.20647-1-Anna.Schumaker@Netapp.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Sender: linux-nfs-owner@vger.kernel.org
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From: Anna Schumaker <Anna.Schumaker@Netapp.com>

There are some workloads where READ_PLUS might end up hurting
performance, so let's be nice to users and provide a way to disable this
operation similar to how READDIR_PLUS can be disabled.

Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
---
 fs/nfs/nfs4client.c       |  3 +++
 fs/nfs/super.c            | 21 +++++++++++++++++++++
 include/linux/nfs4.h      |  4 ++--
 include/linux/nfs_fs_sb.h |  1 +
 4 files changed, 27 insertions(+), 2 deletions(-)

diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c
index 2548405da1f7..2bb603d1a80f 100644
--- a/fs/nfs/nfs4client.c
+++ b/fs/nfs/nfs4client.c
@@ -998,6 +998,9 @@ static int nfs4_server_common_setup(struct nfs_server *server,
 	server->caps |= server->nfs_client->cl_mvops->init_caps;
 	if (server->flags & NFS_MOUNT_NORDIRPLUS)
 			server->caps &= ~NFS_CAP_READDIRPLUS;
+	if (server->options & NFS_OPTION_NO_READ_PLUS)
+		server->caps &= ~NFS_CAP_READ_PLUS;
+
 	/*
 	 * Don't use NFS uid/gid mapping if we're using AUTH_SYS or lower
 	 * authentication.
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 0570391eaa16..5b8701fca5b9 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -90,6 +90,7 @@ enum {
 	Opt_resvport, Opt_noresvport,
 	Opt_fscache, Opt_nofscache,
 	Opt_migration, Opt_nomigration,
+	Opt_readplus, Opt_noreadplus,
 
 	/* Mount options that take integer arguments */
 	Opt_port,
@@ -151,6 +152,8 @@ static const match_table_t nfs_mount_option_tokens = {
 	{ Opt_nofscache, "nofsc" },
 	{ Opt_migration, "migration" },
 	{ Opt_nomigration, "nomigration" },
+	{ Opt_readplus, "readplus" },
+	{ Opt_noreadplus, "noreadplus" },
 
 	{ Opt_port, "port=%s" },
 	{ Opt_rsize, "rsize=%s" },
@@ -690,6 +693,11 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
 	if (nfss->options & NFS_OPTION_MIGRATION)
 		seq_printf(m, ",migration");
 
+	if (nfss->options & NFS_OPTION_NO_READ_PLUS)
+		seq_printf(m,",noreadplus");
+	else
+		seq_printf(m,",readplus");
+
 	if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) {
 		if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
 			seq_printf(m, ",lookupcache=none");
@@ -1324,6 +1332,12 @@ static int nfs_parse_mount_options(char *raw,
 		case Opt_nomigration:
 			mnt->options &= ~NFS_OPTION_MIGRATION;
 			break;
+		case Opt_readplus:
+			mnt->options &= ~NFS_OPTION_NO_READ_PLUS;
+			break;
+		case Opt_noreadplus:
+			mnt->options |= NFS_OPTION_NO_READ_PLUS;
+			break;
 
 		/*
 		 * options that take numeric values
@@ -1626,6 +1640,9 @@ static int nfs_parse_mount_options(char *raw,
 	if (mnt->options & NFS_OPTION_MIGRATION &&
 	    (mnt->version != 4 || mnt->minorversion != 0))
 		goto out_migration_misuse;
+	if (mnt->options & NFS_OPTION_NO_READ_PLUS &&
+	    (mnt->version != 4 || mnt->minorversion < 2))
+		goto out_noreadplus_misuse;
 
 	/*
 	 * verify that any proto=/mountproto= options match the address
@@ -1668,6 +1685,10 @@ static int nfs_parse_mount_options(char *raw,
 	printk(KERN_INFO
 		"NFS: 'migration' not supported for this NFS version\n");
 	return 0;
+out_noreadplus_misuse:
+	printk(KERN_INFO
+		"NFS: 'noreadplus' not supported for this NFS version\n");
+	return 0;
 out_nomem:
 	printk(KERN_INFO "NFS: not enough memory to parse option\n");
 	return 0;
diff --git a/include/linux/nfs4.h b/include/linux/nfs4.h
index db465ad6659b..2fd3cf2061c2 100644
--- a/include/linux/nfs4.h
+++ b/include/linux/nfs4.h
@@ -535,10 +535,10 @@ enum {
 	NFSPROC4_CLNT_LAYOUTSTATS,
 	NFSPROC4_CLNT_CLONE,
 	NFSPROC4_CLNT_COPY,
-	NFSPROC4_CLNT_OFFLOAD_CANCEL,
-	NFSPROC4_CLNT_READ_PLUS,
 
 	NFSPROC4_CLNT_LOOKUPP,
+	NFSPROC4_CLNT_OFFLOAD_CANCEL,
+	NFSPROC4_CLNT_READ_PLUS,
 };
 
 /* nfs41 types */
diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h
index e431c2a7affd..c95be09b84f1 100644
--- a/include/linux/nfs_fs_sb.h
+++ b/include/linux/nfs_fs_sb.h
@@ -157,6 +157,7 @@ struct nfs_server {
 	unsigned int		clone_blksize;	/* granularity of a CLONE operation */
 #define NFS_OPTION_FSCACHE	0x00000001	/* - local caching enabled */
 #define NFS_OPTION_MIGRATION	0x00000002	/* - NFSv4 migration enabled */
+#define NFS_OPTION_NO_READ_PLUS	0x00000004	/* - NFSv4.2 READ_PLUS enabled */
 
 	struct nfs_fsid		fsid;
 	__u64			maxfilesize;	/* maximum file size */
-- 
2.20.1