[RFC v4 7/9] NFS: Add transient mount option

[Joshua Watt <jpewhacker@gmail.com>]

The "transient" option is used to indicate that the server might
disappear unexpectedly, and a more aggressive behavior should be use to
force unmount it. It implies "nosharecache"

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
---
 fs/nfs/super.c                 | 13 ++++++++++++-
 include/uapi/linux/nfs_mount.h |  1 +
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index 71361ca6d6b4..09c413c098ef 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_transient, Opt_notransient,
 
 	/* 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_transient, "transient" },
+	{ Opt_notransient, "notransient" },
 
 	{ Opt_port, "port=%s" },
 	{ Opt_rsize, "rsize=%s" },
@@ -638,6 +641,7 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
 		{ NFS_MOUNT_NORDIRPLUS, ",nordirplus", "" },
 		{ NFS_MOUNT_UNSHARED, ",nosharecache", "" },
 		{ NFS_MOUNT_NORESVPORT, ",noresvport", "" },
+		{ NFS_MOUNT_TRANSIENT, ",transient", "" },
 		{ 0, NULL, NULL }
 	};
 	const struct proc_nfs_info *nfs_infop;
@@ -1329,7 +1333,8 @@ static int nfs_parse_mount_options(char *raw,
 			mnt->flags |= NFS_MOUNT_NORDIRPLUS;
 			break;
 		case Opt_sharecache:
-			mnt->flags &= ~NFS_MOUNT_UNSHARED;
+			mnt->flags &= ~(NFS_MOUNT_UNSHARED |
+					NFS_MOUNT_TRANSIENT);
 			break;
 		case Opt_nosharecache:
 			mnt->flags |= NFS_MOUNT_UNSHARED;
@@ -1356,6 +1361,12 @@ static int nfs_parse_mount_options(char *raw,
 		case Opt_nomigration:
 			mnt->options &= ~NFS_OPTION_MIGRATION;
 			break;
+		case Opt_transient:
+			mnt->flags |= NFS_MOUNT_TRANSIENT | NFS_MOUNT_UNSHARED;
+			break;
+		case Opt_notransient:
+			mnt->flags &= ~NFS_MOUNT_TRANSIENT;
+			break;
 
 		/*
 		 * options that take numeric values
diff --git a/include/uapi/linux/nfs_mount.h b/include/uapi/linux/nfs_mount.h
index e44e00616ab5..6067a9449d9f 100644
--- a/include/uapi/linux/nfs_mount.h
+++ b/include/uapi/linux/nfs_mount.h
@@ -74,5 +74,6 @@ struct nfs_mount_data {
 
 #define NFS_MOUNT_LOCAL_FLOCK	0x100000
 #define NFS_MOUNT_LOCAL_FCNTL	0x200000
+#define NFS_MOUNT_TRANSIENT	0x400000
 
 #endif
-- 
2.13.6