From: Karel Zak <kzak@redhat.com>
Date: Mon, 16 Mar 2026 10:43:19 +0000 (+0100)
Subject: libblkid: add debug message for private DM device skip
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=b85d46a2edf3f871504ca86080102cde93e3725c;p=thirdparty%2Futil-linux.git

libblkid: add debug message for private DM device skip

Add a DBG() trace and set errno = EINVAL when
blkid_new_probe_from_filename() skips a private device-mapper
device, to aid troubleshooting and distinguish from I/O errors.

Addresses: https://github.com/util-linux/util-linux/pull/4120
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/libblkid/src/probe.c b/libblkid/src/probe.c
index d47c22c72..fba7eb124 100644
--- a/libblkid/src/probe.c
+++ b/libblkid/src/probe.c
@@ -224,8 +224,11 @@ blkid_probe blkid_new_probe_from_filename(const char *filename)
 	 * DM_DEVICE_REMOVE would otherwise see EBUSY.
 	 */
 	if (stat(filename, &sb) == 0 && S_ISBLK(sb.st_mode) &&
-	    sysfs_devno_is_dm_private(sb.st_rdev, NULL))
+	    sysfs_devno_is_dm_private(sb.st_rdev, NULL)) {
+		DBG(LOWPROBE, ul_debug("ignore private device mapper device"));
+		errno = EINVAL;
 		return NULL;
+	}
 
 	fd = open(filename, O_RDONLY | O_CLOEXEC | O_NONBLOCK);
 	if (fd < 0)