Extend the exportfs interface to pass fslocations info into the kernel.

Extend exportfs interface to pass fslocations info into the kernel,
using syntax modelled after AIX.  Adds "refer=" and "replicas="
options to /etc/exports to enable use of the kernel fslocation code.

Signed-off-by: Fred Isaman <iisaman@citi.umich.edu>
Signed-off-by: Kevin Coffman <kwc@citi.umich.edu>
Signed-off-by: Neil Brown <neilb@suse.de>

4 files changed, 53 insertions, 2 deletions

diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
index 2e2b6f3..40a6b56 100644
--- a/utils/exportfs/exportfs.c
+++ b/utils/exportfs/exportfs.c
@@ -418,7 +418,19 @@ dump(int verbose)
 				c = dumpopt(c, "anonuid=%d", ep->e_anonuid);
 			if (ep->e_anongid != 65534)
 				c = dumpopt(c, "anongid=%d", ep->e_anongid);
-
+			switch(ep->e_fslocmethod) {
+			case FSLOC_NONE:
+				break;
+			case FSLOC_REFER:
+				c = dumpopt(c, "refer=%s", ep->e_fslocdata);
+				break;
+			case FSLOC_REPLICA:
+				c = dumpopt(c, "replicas=%s", ep->e_fslocdata);
+				break;
+			case FSLOC_STUB:
+				c = dumpopt(c, "fsloc=stub");
+				break;
+			}
 			printf("%c\n", (c != '(')? ')' : ' ');
 		}
 	}
diff --git a/utils/exportfs/exports.man b/utils/exportfs/exports.man
index 3aa8de8..27a30f9 100644
--- a/utils/exportfs/exports.man
+++ b/utils/exportfs/exports.man
@@ -334,6 +334,20 @@ set for such kernels.  Setting both a small number and a UUID is
 supported so the same configuration can be made to work on old and new
 kernels alike.
 
+.TP
+.IR refer= path@host[+host][:path@host[+host]]
+A client referencing the export point will be directed to choose from
+the given list an alternative location for the filesystem.
+(Note that the server must have a mountpoint here, though a different
+filesystem is not required; so, for example,
+.IR "mount --bind" " /path /path"
+is sufficient.)
+.TP
+.IR replicas= path@host[+host][:path@host[+host]]
+If the client asks for alternative locations for the export point, it
+will be given this list of alternatives. (Note that actual replication
+of the filesystem must be handled elsewhere.)
+
 .SS User ID Mapping
 .PP
 .I nfsd
diff --git a/utils/mountd/Makefile.am b/utils/mountd/Makefile.am
index c8500cb..1e76cf8 100644
--- a/utils/mountd/Makefile.am
+++ b/utils/mountd/Makefile.am
@@ -8,7 +8,7 @@ KPREFIX		= @kprefix@
 sbin_PROGRAMS	= mountd
 
 mountd_SOURCES = mountd.c mount_dispatch.c auth.c rmtab.c cache.c \
-		 svc_run.c mountd.h
+		 svc_run.c fsloc.c mountd.h
 mountd_LDADD = ../../support/export/libexport.a \
 	       ../../support/nfs/libnfs.a \
 	       ../../support/misc/libmisc.a \
diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
index 629d567..a14f4f2 100644
--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -28,6 +28,7 @@
 #include "exportfs.h"
 #include "mountd.h"
 #include "xmalloc.h"
+#include "fsloc.h"
 
 #include "blkid/blkid.h"
 
@@ -421,6 +422,29 @@ void nfsd_fh(FILE *f)
 	return;		
 }
 
+static void write_fsloc(FILE *f, struct exportent *ep, char *path)
+{
+	struct servers *servers;
+
+	if (ep->e_fslocmethod == FSLOC_NONE)
+		return;
+
+	servers = replicas_lookup(ep->e_fslocmethod, ep->e_fslocdata, path);
+	if (!servers)
+		return;
+	qword_print(f, "fsloc");
+	qword_printint(f, servers->h_num);
+	if (servers->h_num >= 0) {
+		int i;
+		for (i=0; i<servers->h_num; i++) {
+			qword_print(f, servers->h_mp[i]->h_host);
+			qword_print(f, servers->h_mp[i]->h_path);
+		}
+	}
+	qword_printint(f, servers->h_referral);
+	release_replicas(servers);
+}
+
 static int dump_to_cache(FILE *f, char *domain, char *path, struct exportent *exp)
 {
 	qword_print(f, domain);
@@ -441,6 +465,7 @@ static int dump_to_cache(FILE *f, char *domain, char *path, struct exportent *ex
  			qword_print(f, "uuid");
  			qword_printhex(f, exp->e_uuid, 16);
  		}
+		write_fsloc(f, &exp, path);
 	}
 	return qword_eol(f);
 }