libblkid: remove optimization from verify( funrtion

Now libblkid (the cache based part) tries to probe for the cached
filesystem firstly. This optimization is broken, because:

  * new another superblock could be on the device and the original
    is already obsolete
  * we still need to probe for partitions and raids
  * the code was too fragile

The patch also suggests lsblk --fs in blkid.8 for end users. lsblk
read information from used db.

Reported-by: Andreas Hofmeister <andi@collax.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libblkid/src/verify.c b/libblkid/src/verify.c
index 4bab4de205484625a79f0911aebcd4bc7e3dc57d..0f48c48e2dbbf3da6bb749b2e0dbfdbab864b455 100644 (file)
--- a/libblkid/src/verify.c
+++ b/libblkid/src/verify.c
@@ -43,26 +43,6 @@ static void blkid_probe_to_tags(blkid_probe pr, blkid_dev dev)
                        blkid_set_tag(dev, name, data, len);
                }
        }
-
-       /*
-        * remove obsolete tags
-        */
-       if (!nvals || !blkid_probe_has_value(pr, "LABEL"))
-               blkid_set_tag(dev, "LABEL", NULL, 0);
-       if (!nvals || !blkid_probe_has_value(pr, "UUID"))
-               blkid_set_tag(dev, "UUID", NULL, 0);
-       if (!nvals || !blkid_probe_has_value(pr, "PART_ENTRY_UUID"))
-               blkid_set_tag(dev, "PARTUUID", NULL, 0);
-       if (!nvals || !blkid_probe_has_value(pr, "PART_ENTRY_NAME"))
-               blkid_set_tag(dev, "PARTLABEL", NULL, 0);
-       if (!nvals || !blkid_probe_has_value(pr, "TYPE"))
-               blkid_set_tag(dev, "TYPE", NULL, 0);
-       if (!nvals || !blkid_probe_has_value(pr, "SEC_TYPE"))
-               blkid_set_tag(dev, "SEC_TYPE", NULL, 0);
-       if (!nvals || !blkid_probe_has_value(pr, "EXT_JOURNAL"))        /* extN */
-               blkid_set_tag(dev, "EXT_JOURNAL", NULL, 0);
-       if (!nvals || !blkid_probe_has_value(pr, "MOUNT"))              /* ocfs */
-               blkid_set_tag(dev, "MOUNT", NULL, 0);
 }
 
 /*
@@ -76,9 +56,10 @@ static void blkid_probe_to_tags(blkid_probe pr, blkid_dev dev)
  */
 blkid_dev blkid_verify(blkid_cache cache, blkid_dev dev)
 {
+       blkid_tag_iterate iter;
+       const char *type, *value;
        struct stat st;
        time_t diff, now;
-       char *fltr[2];
        int fd;
 
        if (!dev)
@@ -155,64 +136,29 @@ blkid_dev blkid_verify(blkid_cache cache, blkid_dev dev)
                return NULL;
        }
 
-       blkid_probe_enable_superblocks(cache->probe, TRUE);
+       /* remove old cache info */
+       iter = blkid_tag_iterate_begin(dev);
+       while (blkid_tag_next(iter, &type, &value) == 0)
+               blkid_set_tag(dev, type, NULL, 0);
+       blkid_tag_iterate_end(iter);
 
+       /* enable superblocks probing */
+       blkid_probe_enable_superblocks(cache->probe, TRUE);
        blkid_probe_set_superblocks_flags(cache->probe,
                BLKID_SUBLKS_LABEL | BLKID_SUBLKS_UUID |
                BLKID_SUBLKS_TYPE | BLKID_SUBLKS_SECTYPE);
 
-       /*
-        * If we already know the type, then try that first.
-        */
-       if (dev->bid_type) {
-               blkid_tag_iterate iter;
-               const char *type, *value;
-
-               fltr[0] = dev->bid_type;
-               fltr[1] = NULL;
-
-               blkid_probe_filter_superblocks_type(cache->probe,
-                               BLKID_FLTR_ONLYIN, fltr);
-
-               if (blkid_do_probe(cache->probe) == 0) {
-                       /*
-                        * Cool, we found FS type, let's also read PART{UUID,LABEL}
-                        */
-                       blkid_probe_enable_superblocks(cache->probe, FALSE);
-                       blkid_probe_enable_partitions(cache->probe, TRUE);
-                       blkid_probe_set_partitions_flags(cache->probe, BLKID_PARTS_ENTRY_DETAILS);
-                       if (blkid_do_probe(cache->probe) == 0)
-                               goto found_type;
-               }
-
-               blkid_probe_enable_superblocks(cache->probe, TRUE);
-               blkid_probe_invert_superblocks_filter(cache->probe);
-
-               /*
-                * Zap the device filesystem information and try again
-                */
-               DBG(DEBUG_PROBE,
-                   printf("previous fs type %s not valid, "
-                          "trying full probe\n", dev->bid_type));
-               iter = blkid_tag_iterate_begin(dev);
-               while (blkid_tag_next(iter, &type, &value) == 0)
-                       blkid_set_tag(dev, type, 0, 0);
-               blkid_tag_iterate_end(iter);
-       }
-
+       /* enable partitions probing */
        blkid_probe_enable_partitions(cache->probe, TRUE);
        blkid_probe_set_partitions_flags(cache->probe, BLKID_PARTS_ENTRY_DETAILS);
 
-       /*
-        * Probe for all types.
-        */
+       /* probe */
        if (blkid_do_safeprobe(cache->probe)) {
                /* found nothing or error */
                blkid_free_dev(dev);
                dev = NULL;
        }
 
-found_type:
        if (dev) {
 #ifdef HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
                struct timeval tv;

diff --git a/misc-utils/blkid.8 b/misc-utils/blkid.8
index 2ba1ab43fcaeadf9589aca4e0f113feddae792c4..eb8d71608e299be46ec330979f874b147a1c23b0 100644 (file)
--- a/misc-utils/blkid.8
+++ b/misc-utils/blkid.8
@@ -64,6 +64,17 @@ library.  It can determine the type of content (e.g. filesystem or swap)
 that a block device holds, and also attributes (tokens, NAME=value pairs)
 from the content metadata (e.g. LABEL or UUID fields).
 .PP
+Note that
+.B blkid
+reads information directly from devices and for non-root users
+it returns cached unverified information. It's better to use
+.B lsblk --fs
+to get user-friendly overview about filesystems and devices. 
+.BR lsblk (8)
+is also easy to use in scripts.
+.B blkid
+is mostly designed for system services and to test libblkid functionality.
+.PP
 .B blkid
 has two main forms of operation: either searching for a device with a
 specific NAME=value pair, or displaying NAME=value pairs for one or