new "mountpoint" export option.

5 files changed, 68 insertions, 2 deletions

diff --git a/utils/exportfs/Makefile b/utils/exportfs/Makefile
index 851a294..8cd7029 100644
--- a/utils/exportfs/Makefile
+++ b/utils/exportfs/Makefile
@@ -5,7 +5,7 @@
 PROGRAM	= exportfs
 OBJS	= exportfs.o
 LIBDEPS	= $(TOP)support/lib/libexport.a $(TOP)/support/lib/libnfs.a
-LIBS	= -lexport -lnfs
+LIBS	= -lexport -lnfs -lmisc
 MAN8	= exportfs
 MAN5	= exports
 
diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
index 936dff5..bd48e98 100644
--- a/utils/exportfs/exportfs.c
+++ b/utils/exportfs/exportfs.c
@@ -147,6 +147,16 @@ exports_update(int verbose)
 	nfs_export 	*exp;
 
 	for (exp = exportlist[MCL_FQDN]; exp; exp=exp->m_next) {
+		/* check mountpoint option */
+		if (exp->m_mayexport && 
+		    exp->m_export.e_mountpoint &&
+		    !is_mountpoint(exp->m_export.e_mountpoint[0]?
+				   exp->m_export.e_mountpoint:
+				   exp->m_export.e_path)) {
+			printf("%s not exported as %s not a mountpoint.\n",
+			       exp->m_export.e_path, exp->m_export.e_mountpoint);
+			exp->m_mayexport = 0;
+		}
 		if (exp->m_mayexport && ((exp->m_exported<1) || exp->m_changed)) {
 			if (verbose)
 				printf("%sexporting %s:%s to kernel\n",
@@ -366,6 +376,10 @@ dump(int verbose)
 				c = dumpopt(c, "insecure_locks");
 			if (ep->e_flags & NFSEXP_FSID)
 				c = dumpopt(c, "fsid=%d", ep->e_fsid);
+			if (ep->e_mountpoint)
+				c = dumpopt(c, "mountpoint%s%s", 
+					    ep->e_mountpoint[0]?"=":"", 
+					    ep->e_mountpoint);
 			if (ep->e_maptype == CLE_MAP_UGIDD)
 				c = dumpopt(c, "mapping=ugidd");
 			else if (ep->e_maptype == CLE_MAP_FILE)
diff --git a/utils/exportfs/exports.man b/utils/exportfs/exports.man
index 7ab7640..6223944 100644
--- a/utils/exportfs/exports.man
+++ b/utils/exportfs/exports.man
@@ -237,6 +237,25 @@ or
 '''.TP
 '''.IR link_absolute
 '''Leave all symbolic link as they are. This is the default operation.
+
+.TP
+.IR mountpoint= path
+.TP
+.I mp
+This option makes it possible to only export a directory if it has
+successfully been mounted.
+If no path is given (e.g.
+.IR mountpoint " or " mp )
+then the export point must also be a mount point.  If it isn't then
+the export point is not exported.  This allows you to be sure that the
+directory underneath a mountpoint will never be exported by accident
+if, for example, the filesystem failed to mount due to a disc error.
+
+If a path is given (e.g.
+.IR mountpoint= "/path or " mp= /path)
+then the nominted path must be a mountpoint for the exportpoint to be
+exported.
+
 .SS User ID Mapping
 .PP
 .I nfsd
diff --git a/utils/mountd/cache.c b/utils/mountd/cache.c
index c5bc53f..9d7d20d 100644
--- a/utils/mountd/cache.c
+++ b/utils/mountd/cache.c
@@ -100,6 +100,7 @@ void nfsd_fh(FILE *f)
 	struct exportent *found = NULL;
 	nfs_export *exp;
 	int i;
+	int dev_missing = 0;
 
 	if (readline(fileno(f), &lbuf, &lbuflen) != 1)
 		return;
@@ -145,6 +146,11 @@ void nfsd_fh(FILE *f)
 				continue;
 			if (fsidtype == 0) {
 				struct stat stb;
+				if (exp->m_export.e_mountpoint &&
+				    !is_mountpoint(exp->m_export.e_mountpoint[0]?
+						   exp->m_export.e_mountpoint:
+						   exp->m_export.e_path))
+					dev_missing ++;
 				if (stat(exp->m_export.e_path, &stb) != 0)
 					continue;
 				if (stb.st_ino != inode)
@@ -158,11 +164,31 @@ void nfsd_fh(FILE *f)
 				found = &exp->m_export;
 			else if (strcmp(found->e_path, exp->m_export.e_path)!= 0)
 			{
-				xlog(L_WARNING, "%s and %s have name filehandle for %s, using first",
+				xlog(L_WARNING, "%s and %s have same filehandle for %s, using first",
 				     found->e_path, exp->m_export.e_path, dom);
 			}
 		}
 	}
+	if (found && 
+	    found->e_mountpoint &&
+	    !is_mountpoint(found->e_mountpoint[0]?
+			   found->e_mountpoint:
+			   found->e_path)) {
+		/* Cannot export this yet 
+		 * should log a warning, but need to rate limit
+		   xlog(L_WARNING, "%s not exported as %d not a mountpoint",
+		   found->e_path, found->e_mountpoint);
+		 */
+		/* FIXME we need to make sure we re-visit this later */
+		goto out;
+	}
+	if (!found && dev_missing) {
+		/* The missing dev could be what we want, so just be
+		 * quite rather than returning stale yet
+		 */
+		goto out;
+	}
+
 	cache_export_ent(dom, found);
 
 	qword_print(f, dom);
diff --git a/utils/mountd/mountd.c b/utils/mountd/mountd.c
index b1bce1d..3769c92 100644
--- a/utils/mountd/mountd.c
+++ b/utils/mountd/mountd.c
@@ -282,6 +282,13 @@ get_rootfh(struct svc_req *rqstp, dirpath *path, int *error, int v3)
 		xlog(L_WARNING, "request to export directory %s below nearest filesystem %s",
 		     p, exp->m_export.e_path);
 		*error = NFSERR_ACCES;
+	} else if (exp->m_export.e_mountpoint &&
+		   !is_mountpoint(exp->m_export.e_mountpoint[0]?
+				  exp->m_export.e_mountpoint:
+				  exp->m_export.e_path)) {
+		xlog(L_WARNING, "request to export an unmounted filesystem: %s",
+		     p);
+		*error = NFSERR_NOENT;
 	} else if (new_cache) {
 		/* This will be a static private nfs_export with just one
 		 * address.  We feed it to kernel then extract the filehandle,