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 0ddb2516a8d5e8327441555ca668788f6c1850e6..292087b8c656bc07bd2cd5adea7f76815a7732f8 100644 (file)
--- 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 183c9ea8c5b27b747925b832405333543eba97f0..f7fe23dda5ba26b8453e56d99bb56476bd41ec75 100644 (file)
--- 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 04141d153a676b70e9e789f1a5369c93b7ab0625..999f035d9a0227426f3bd112fda3df6fda416321 100644 (file)
--- 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 b539278aaf0354d8f77b56bcfecac7ccce7e2371..31bacb50c87ce9476c6e69810dbdde95ee47aa8d 100644 (file)
--- 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);