blkid: If the device mtime is newer that the cache time, force a revalidation

This fixes problems turned up by a test case written by Erez Zadok's
group which constantly reformats filesystems.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/lib/blkid/probe.c b/lib/blkid/probe.c
index 4964209..62ab392 100644 (file)
--- a/lib/blkid/probe.c
+++ b/lib/blkid/probe.c
@@ -1214,33 +1214,39 @@ blkid_dev blkid_verify(blkid_cache cache, blkid_dev dev)
        now = time(0);
        diff = now - dev->bid_time;
 
-       if ((now > dev->bid_time) && (diff > 0) && 
+       if (stat(dev->bid_name, &st) < 0) {
+               DBG(DEBUG_PROBE,
+                   printf("blkid_verify: error %s (%d) while "
+                          "trying to stat %s\n", strerror(errno), errno,
+                          dev->bid_name));
+       open_err:
+               if ((errno == EPERM) || (errno == EACCES) || (errno == ENOENT)) {
+                       /* We don't have read permission, just return cache data. */
+                       DBG(DEBUG_PROBE, printf("returning unverified data for %s\n",
+                                               dev->bid_name));
+                       return dev;
+               }
+               blkid_free_dev(dev);
+               return NULL;
+       }
+
+       if ((now >= dev->bid_time) &&
+           (st.st_mtime <= dev->bid_time) &&
            ((diff < BLKID_PROBE_MIN) || 
             (dev->bid_flags & BLKID_BID_FL_VERIFIED &&
              diff < BLKID_PROBE_INTERVAL)))
                return dev;
 
        DBG(DEBUG_PROBE,
-           printf("need to revalidate %s (time since last check %llu)\n", 
-                  dev->bid_name, (unsigned long long)diff));
-
-       if (((probe.fd = open(dev->bid_name, O_RDONLY)) < 0) ||
-           (fstat(probe.fd, &st) < 0)) {
-               if (probe.fd >= 0) close(probe.fd);
-               if ((errno != EPERM) && (errno != EACCES) &&
-                   (errno != ENOENT)) {
-                       DBG(DEBUG_PROBE, 
-                           printf("blkid_verify: error %s (%d) while "
-                                  "opening %s\n", strerror(errno), errno, 
-                                  dev->bid_name));
-                       blkid_free_dev(dev);
-                       return NULL;
-               }
-               /* We don't have read permission, just return cache data. */
-               DBG(DEBUG_PROBE,
-                   printf("returning unverified data for %s\n",
-                          dev->bid_name));
-               return dev;
+           printf("need to revalidate %s (cache time %d, stat time %d,\n\t"
+                  "time since last check %lu)\n",
+                  dev->bid_name, dev->bid_time, st.st_mtime, (unsigned long)diff));
+
+       if ((probe.fd = open(dev->bid_name, O_RDONLY)) < 0) {
+               DBG(DEBUG_PROBE, printf("blkid_verify: error %s (%d) while "
+                                       "opening %s\n", strerror(errno), errno, 
+                                       dev->bid_name));
+               goto open_err;
        }
 
        probe.cache = cache;