From: Jeff Layton <jlayton@redhat.com>
Date: Wed, 9 May 2007 14:19:33 +0000 (-0400)
Subject: nfs-utils: have mountd hold open etab file to force inode number to change
X-Git-Tag: nfs-utils-1-1-0~1
X-Git-Url: https://git.decadent.org.uk/gitweb/?a=commitdiff_plain;h=fd9097110f74f39bce89ec3a341fd9b686a68719;p=nfs-utils.git

nfs-utils: have mountd hold open etab file to force inode number to change

This patch changes mountd to hold the etab file open so that when it's
changed by exportfs, the inode number should change. We then change
auth_reload to reload the file based on whether st_ino is different
from the last time it was checked. It also changes auth_reload to
maintain a static counter value and return it instead of a timestamp
and fixes up get_exportlist accordingly. Finally, it adds some
comments to xtab_write to warn people about editing the etab in place.

Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: NeilBrown <neilb@suse.de>
---

diff --git a/support/export/xtab.c b/support/export/xtab.c
index 0ddb251..292087b 100644
--- a/support/export/xtab.c
+++ b/support/export/xtab.c
@@ -80,6 +80,12 @@ xtab_export_read(void)
 	return xtab_read(_PATH_ETAB, 1);
 }
 
+/*
+ * mountd now keeps an open fd for the etab at all times to make sure that the
+ * inode number changes when the xtab_export_write is done. If you change the
+ * routine below such that the files are edited in place, then you'll need to
+ * fix the auth_reload logic as well...
+ */
 static int
 xtab_write(char *xtab, char *xtabtmp, int is_export)
 {
diff --git a/utils/mountd/auth.c b/utils/mountd/auth.c
index 183c9ea..f7fe23d 100644
--- a/utils/mountd/auth.c
+++ b/utils/mountd/auth.c
@@ -14,6 +14,7 @@
 #include <netinet/in.h>
 #include <arpa/inet.h>
 #include <errno.h>
+#include <unistd.h>
 #include "misc.h"
 #include "nfslib.h"
 #include "exportfs.h"
@@ -46,24 +47,34 @@ auth_init(char *exports)
 	xtab_mount_write();
 }
 
-time_t
+unsigned int
 auth_reload()
 {
 	struct stat		stb;
-	static time_t		last_modified = 0;
-
-	if (stat(_PATH_ETAB, &stb) < 0)
+	static ino_t		last_inode;
+	static int		last_fd;
+	static unsigned int	counter;
+	int			fd;
+
+	if ((fd = open(_PATH_ETAB, O_RDONLY)) < 0) {
+		xlog(L_FATAL, "couldn't open %s", _PATH_ETAB);
+	} else if (fstat(fd, &stb) < 0) {
 		xlog(L_FATAL, "couldn't stat %s", _PATH_ETAB);
-	if (stb.st_mtime == last_modified)
-		return last_modified;
-	last_modified = stb.st_mtime;
+	} else if (stb.st_ino == last_inode) {
+		close(fd);
+		return counter;
+	} else {
+		close(last_fd);
+		last_fd = fd;
+		last_inode = stb.st_ino;
+	}
 
 	export_freeall();
 	memset(&my_client, 0, sizeof(my_client));
-	// export_read(export_file);
 	xtab_export_read();
+	++counter;
 
-	return last_modified;
+	return counter;
 }
 
 static nfs_export *
diff --git a/utils/mountd/mountd.c b/utils/mountd/mountd.c
index 04141d1..999f035 100644
--- a/utils/mountd/mountd.c
+++ b/utils/mountd/mountd.c
@@ -465,18 +465,18 @@ static exports
 get_exportlist(void)
 {
 	static exports		elist = NULL;
-	static time_t		etime = 0;
-	time_t			atime;
 	struct exportnode	*e, *ne;
 	struct groupnode	*g, *ng, *c, **cp;
 	nfs_export		*exp;
 	int			i;
+	static unsigned int	ecounter;
+	unsigned int		acounter;
 
-	atime = auth_reload();
-	if (elist && atime == etime)
+	acounter = auth_reload();
+	if (elist && acounter == ecounter)
 		return elist;
 
-	etime = atime;
+	ecounter = acounter;
 
 	for (e = elist; e != NULL; e = ne) {
 		ne = e->ex_next;
diff --git a/utils/mountd/mountd.h b/utils/mountd/mountd.h
index b539278..31bacb5 100644
--- a/utils/mountd/mountd.h
+++ b/utils/mountd/mountd.h
@@ -40,7 +40,7 @@ bool_t		mount_mnt_3_svc(struct svc_req *, dirpath *, mountres3 *);
 
 void		mount_dispatch(struct svc_req *, SVCXPRT *);
 void		auth_init(char *export_file);
-time_t		auth_reload(void);
+unsigned int	auth_reload(void);
 nfs_export *	auth_authenticate(char *what, struct sockaddr_in *sin,
 					char *path);
 void		auth_export(nfs_export *exp);