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>

7 files changed, 98 insertions, 3 deletions

diff --git a/support/include/exportfs.h b/support/include/exportfs.h
index 10f38c7..458611b 100644
--- a/support/include/exportfs.h
+++ b/support/include/exportfs.h
@@ -23,6 +23,13 @@ enum {
 	MCL_MAXTYPES
 };
 
+enum {
+	FSLOC_NONE = 0,
+	FSLOC_REFER,
+	FSLOC_REPLICA,
+	FSLOC_STUB
+};
+
 typedef struct mclient {
 	struct mclient *	m_next;
 	char			m_hostname[NFSCLNT_IDMAX+1];
diff --git a/support/include/nfslib.h b/support/include/nfslib.h
index 13a89da..c085029 100644
--- a/support/include/nfslib.h
+++ b/support/include/nfslib.h
@@ -80,6 +80,8 @@ struct exportent {
 	int		e_nsqgids;
 	int		e_fsid;
 	char *		e_mountpoint;
+	int             e_fslocmethod;
+	char *          e_fslocdata;
 	char *		e_uuid;
 };
 
diff --git a/support/nfs/exports.c b/support/nfs/exports.c
index 0994ea2..31b38c3 100644
--- a/support/nfs/exports.c
+++ b/support/nfs/exports.c
@@ -100,6 +100,8 @@ getexportent(int fromkernel, int fromexports)
 		def_ee.e_squids = NULL;
 		def_ee.e_sqgids = NULL;
 		def_ee.e_mountpoint = NULL;
+		def_ee.e_fslocmethod = FSLOC_NONE;
+		def_ee.e_fslocdata = NULL;
 		def_ee.e_nsquids = 0;
 		def_ee.e_nsqgids = 0;
 
@@ -225,7 +227,22 @@ putexportent(struct exportent *ep)
 	if (ep->e_mountpoint)
 		fprintf(fp, "mountpoint%s%s,",
 			ep->e_mountpoint[0]?"=":"", ep->e_mountpoint);
-
+	switch (ep->e_fslocmethod) {
+	case FSLOC_NONE:
+		break;
+	case FSLOC_REFER:
+		fprintf(fp, "refer=%s,", ep->e_fslocdata);
+		break;
+	case FSLOC_REPLICA:
+		fprintf(fp, "replicas=%s,", ep->e_fslocdata);
+		break;
+	case FSLOC_STUB:
+		fprintf(fp, "fsloc=stub,");
+		break;
+	default:
+		xlog(L_ERROR, "unknown fsloc method for %s:%s",
+		     ep->e_hostname, ep->e_path);
+	}
 	fprintf(fp, "mapping=");
 	switch (ep->e_maptype) {
 	case CLE_MAP_IDENT:
@@ -288,6 +305,8 @@ dupexportent(struct exportent *dst, struct exportent *src)
 	}
 	if (src->e_mountpoint)
 		dst->e_mountpoint = strdup(src->e_mountpoint);
+	if (src->e_fslocdata)
+		dst->e_fslocdata = strdup(src->e_fslocdata);
 }
 
 struct exportent *
@@ -302,6 +321,8 @@ mkexportent(char *hname, char *path, char *options)
 	ee.e_squids = NULL;
 	ee.e_sqgids = NULL;
 	ee.e_mountpoint = NULL;
+	ee.e_fslocmethod = FSLOC_NONE;
+	ee.e_fslocdata = NULL;
 	ee.e_nsquids = 0;
 	ee.e_nsqgids = 0;
 	ee.e_uuid = NULL;
@@ -483,6 +504,20 @@ bad_option:
 				ep->e_mountpoint = strdup(mp+1);
 			else
 				ep->e_mountpoint = strdup("");
+		} else if (strncmp(opt, "fsloc=", 6) == 0) {
+			if (strcmp(opt+6, "stub") == 0)
+				ep->e_fslocmethod = FSLOC_STUB;
+			else {
+				xlog(L_ERROR, "%s:%d: bad option %s\n",
+				     flname, flline, opt);
+				goto bad_option;
+			}
+		} else if (strncmp(opt, "refer=", 6) == 0) {
+			ep->e_fslocmethod = FSLOC_REFER;
+			ep->e_fslocdata = strdup(opt+6);
+		} else if (strncmp(opt, "replicas=", 9) == 0) {
+			ep->e_fslocmethod = FSLOC_REPLICA;
+			ep->e_fslocdata = strdup(opt+9);
 		} else {
 			xlog(L_ERROR, "%s:%d: unknown keyword \"%s\"\n",
 					flname, flline, opt);
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);
 }