blkid: improve RAIDs and tiny devices probing

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/misc-utils/blkid.c b/misc-utils/blkid.c
index 08df09e1a899f65b994433673509db0eeebd26a3..db07a39bad3119cc0da51c265787f44ab78f7871 100644 (file)
--- a/misc-utils/blkid.c
+++ b/misc-utils/blkid.c
@@ -419,7 +419,7 @@ static int lowprobe_device(blkid_probe pr, const char *devname,     char *show[],
 {
        const char *data;
        const char *name;
-       int nvals = 0, n, num = 1, has_pt = 0;
+       int nvals = 0, n, num = 1;
        size_t len;
        int fd;
        int rc = 0;
@@ -436,62 +436,35 @@ static int lowprobe_device(blkid_probe pr, const char *devname,   char *show[],
 
        if (fstat(fd, &st))
                goto done;
-       /*
-        * partitions probing
-        */
-       blkid_probe_enable_superblocks(pr, 0);  /* enabled by default ;-( */
 
        blkid_probe_enable_partitions(pr, 1);
-
-       /* This is for PART_ENTRY_{UUID,NAME,TYPE,...} values and it will
-        * open() whole-disk device.
-        */
        blkid_probe_set_partitions_flags(pr, BLKID_PARTS_ENTRY_DETAILS);
 
-       rc = blkid_do_fullprobe(pr);
-       blkid_probe_enable_partitions(pr, 0);
-
-       if (rc < 0)
-               goto done;      /* -1 = error, 1 = nothing, 0 = succes */
-
-       if (blkid_probe_lookup_value(pr, "PTTYPE", NULL, NULL) == 0)
-               /* partition table detected */
-               has_pt = 1;
-
-       /*
-        * filesystems/raids probing
-        *
-        * Q: Why do we try to probe for FS/RAID on device with partiton table?
-        *
-        * A: For some devices the kernel creates partitions because it is too
-        *    dumb to find out, that the device contains a RAID signature or
-        *    other metadata that signifies, that this device should not be
-        *    handled.
-        *
-        *    Many RAID signatures are at the end of the device, or at least
-        *    still allow that the volume contains a partition table at the
-        *    beginning of the device, which the kernel will find. Udev needs
-        *    to look at the disk, if there are such RAID signatures, and then
-        *    it needs to handle it, and in many cases just kill all the
-        *    wrongly kernel-created partitions.
-        *
-        * -- Kay Sievers
-        *    http://thread.gmane.org/gmane.linux.utilities.util-linux-ng/2888/focus=2890
-        *
-        * This all is unncecessary for very small devices (<= 1.44MiB).
-        */
-       if (has_pt == 0 || S_ISCHR(st.st_mode) ||
-           blkid_probe_get_size(pr) > 1024 * 1440) {
+       if (!S_ISCHR(st.st_mode) && blkid_probe_get_size(pr) <= 1024 * 1440) {
                /*
-                * filesystems/RAIDs probing
+                * check if the small disk is partitioned, if yes then
+                * don't probe for filesystems.
                 */
-               blkid_probe_enable_superblocks(pr, 1);
+               blkid_probe_enable_superblocks(pr, 0);
 
-               rc = blkid_do_safeprobe(pr);
+               rc = blkid_do_fullprobe(pr);
                if (rc < 0)
-                       goto done;
+                       goto done;      /* -1 = error, 1 = nothing, 0 = succes */
+
+               if (blkid_probe_lookup_value(pr, "PTTYPE", NULL, NULL) == 0)
+                       /* partition table detected */
+                       goto print_vals;
+
+               /* small whole-disk is unpartitioned, probe for filesystems only */
+               blkid_probe_enable_partitions(pr, 0);
        }
 
+       blkid_probe_enable_superblocks(pr, 1);
+
+       rc = blkid_do_safeprobe(pr);
+       if (rc < 0)
+               goto done;
+print_vals:
        nvals = blkid_probe_numof_values(pr);
 
        if (nvals && !first && output & OUTPUT_UDEV_LIST)