path: root/fs/nfs/super.c
diff options
authorChuck Lever <chuck.lever@oracle.com>2012-09-14 17:24:11 -0400
committerTrond Myklebust <Trond.Myklebust@netapp.com>2012-10-01 15:33:33 -0700
commit896526174ce2b6a773e187ebe5a047b68230e2c4 (patch)
tree0f994ab0746003d4a6355086b24051664c89612d /fs/nfs/super.c
parentba9b584c1dc37851d9c6ca6d0d2ccba55d9aad04 (diff)
NFS: Introduce "migration" mount option
Currently, the Linux client uses a unique nfs_client_id4.id string when identifying itself to distinct NFS servers. To support transparent state migration, the Linux client will have to use the same nfs_client_id4 string for all servers it communicates with (also known as the "uniform client string" approach). Otherwise NFS servers can not recognize that open and lock state need to be merged after a file system transition. Unfortunately, there are some NFSv4.0 servers currently in the field that do not tolerate the uniform client string approach. Thus, by default, our NFSv4.0 mounts will continue to use the current approach, and we introduce a mount option that switches them to use the uniform model. Client administrators must identify which servers can be mounted with this option. Eventually most NFSv4.0 servers will be able to handle the uniform approach, and we can change the default. The first mount of a server controls the behavior for all subsequent mounts for the lifetime of that set of mounts of that server. After the last mount of that server is gone, the client erases the data structure that tracks the lease. A subsequent lease may then honor a different "migration" setting. This patch adds only the infrastructure for parsing the new mount option. Support for uniform client strings is added in a subsequent patch. Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Diffstat (limited to 'fs/nfs/super.c')
1 files changed, 20 insertions, 0 deletions
diff --git a/fs/nfs/super.c b/fs/nfs/super.c
index b8eda700584b..056138d45c11 100644
--- a/fs/nfs/super.c
+++ b/fs/nfs/super.c
@@ -88,6 +88,7 @@ enum {
Opt_sharecache, Opt_nosharecache,
Opt_resvport, Opt_noresvport,
Opt_fscache, Opt_nofscache,
+ Opt_migration, Opt_nomigration,
/* Mount options that take integer arguments */
@@ -147,6 +148,8 @@ static const match_table_t nfs_mount_option_tokens = {
{ Opt_noresvport, "noresvport" },
{ Opt_fscache, "fsc" },
{ Opt_nofscache, "nofsc" },
+ { Opt_migration, "migration" },
+ { Opt_nomigration, "nomigration" },
{ Opt_port, "port=%s" },
{ Opt_rsize, "rsize=%s" },
@@ -676,6 +679,9 @@ static void nfs_show_mount_options(struct seq_file *m, struct nfs_server *nfss,
if (nfss->options & NFS_OPTION_FSCACHE)
seq_printf(m, ",fsc");
+ if (nfss->options & NFS_OPTION_MIGRATION)
+ seq_printf(m, ",migration");
if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONEG) {
if (nfss->flags & NFS_MOUNT_LOOKUP_CACHE_NONE)
seq_printf(m, ",lookupcache=none");
@@ -1243,6 +1249,12 @@ static int nfs_parse_mount_options(char *raw,
mnt->fscache_uniq = NULL;
+ case Opt_migration:
+ mnt->options |= NFS_OPTION_MIGRATION;
+ break;
+ case Opt_nomigration:
+ mnt->options &= NFS_OPTION_MIGRATION;
+ break;
* options that take numeric values
@@ -1535,6 +1547,10 @@ static int nfs_parse_mount_options(char *raw,
if (mnt->minorversion && mnt->version != 4)
goto out_minorversion_mismatch;
+ if (mnt->options & NFS_OPTION_MIGRATION &&
+ mnt->version != 4 && mnt->minorversion != 0)
+ goto out_migration_misuse;
* verify that any proto=/mountproto= options match the address
* familiies in the addr=/mountaddr= options.
@@ -1572,6 +1588,10 @@ out_minorversion_mismatch:
printk(KERN_INFO "NFS: mount option vers=%u does not support "
"minorversion=%u\n", mnt->version, mnt->minorversion);
return 0;
+ printk(KERN_INFO
+ "NFS: 'migration' not supported for this NFS version\n");
+ return 0;
printk(KERN_INFO "NFS: not enough memory to parse option\n");
return 0;