libblkid: don't use CDROM_GET_CAPABILITY ioctl for DM devices

For some reason kernel commit e980f62353c697cbf0c4325e43df6e44399aeb64
add extra warning when the ioctl is used for DM devices. It seems we
can avoid this ioctl when the device has dm/uuid.

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=1469532
Signed-off-by: Karel Zak <kzak@redhat.com>

5 files changed, 19 insertions, 11 deletions

diff --git a/disk-utils/fdisk-list.c b/disk-utils/fdisk-list.c
index 08732e95a..a46883d18 100644
--- a/disk-utils/fdisk-list.c
+++ b/disk-utils/fdisk-list.c
@@ -334,7 +334,7 @@ char *next_proc_partition(FILE **f)
 		if (devno <= 0)
 			continue;
 
-		if (sysfs_devno_is_lvm_private(devno) ||
+		if (sysfs_devno_is_lvm_private(devno, NULL) ||
 		    sysfs_devno_is_wholedisk(devno) <= 0)
 			continue;
 
diff --git a/include/sysfs.h b/include/sysfs.h
index 36d3cbd4f..7e715ee85 100644
--- a/include/sysfs.h
+++ b/include/sysfs.h
@@ -81,7 +81,7 @@ extern int sysfs_is_partition_dirent(DIR *dir, struct dirent *d,
 extern int sysfs_devno_to_wholedisk(dev_t dev, char *diskname,
             size_t len, dev_t *diskdevno);
 
-extern int sysfs_devno_is_lvm_private(dev_t devno);
+extern int sysfs_devno_is_lvm_private(dev_t devno, char **uuid);
 extern int sysfs_devno_is_wholedisk(dev_t devno);
 
 extern int sysfs_scsi_get_hctl(struct sysfs_cxt *cxt, int *h,
diff --git a/lib/sysfs.c b/lib/sysfs.c
index 68b43aaa3..e8125e511 100644
--- a/lib/sysfs.c
+++ b/lib/sysfs.c
@@ -833,31 +833,35 @@ err:
 }
 
 /*
- * Returns 1 if the device is private LVM device.
+ * Returns 1 if the device is private LVM device. The @uuid (if not NULL)
+ * returns DM device UUID, use free() to deallocate.
  */
-int sysfs_devno_is_lvm_private(dev_t devno)
+int sysfs_devno_is_lvm_private(dev_t devno, char **uuid)
 {
 	struct sysfs_cxt cxt = UL_SYSFSCXT_EMPTY;
-	char *uuid = NULL;
+	char *id = NULL;
 	int rc = 0;
 
 	if (sysfs_init(&cxt, devno, NULL) != 0)
 		return 0;
 
-	uuid = sysfs_strdup(&cxt, "dm/uuid");
+	id = sysfs_strdup(&cxt, "dm/uuid");
 
 	/* Private LVM devices use "LVM-<uuid>-<name>" uuid format (important
 	 * is the "LVM" prefix and "-<name>" postfix).
 	 */
-	if (uuid && strncmp(uuid, "LVM-", 4) == 0) {
-		char *p = strrchr(uuid + 4, '-');
+	if (id && strncmp(id, "LVM-", 4) == 0) {
+		char *p = strrchr(id + 4, '-');
 
 		if (p && *(p + 1))
 			rc = 1;
 	}
 
 	sysfs_deinit(&cxt);
-	free(uuid);
+	if (uuid)
+		*uuid = id;
+	else
+		free(id);
 	return rc;
 }
 
diff --git a/libblkid/src/probe.c b/libblkid/src/probe.c
index 9f56f528f..21cd790e9 100644
--- a/libblkid/src/probe.c
+++ b/libblkid/src/probe.c
@@ -862,6 +862,7 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
 {
 	struct stat sb;
 	uint64_t devsiz = 0;
+	char *dm_uuid = NULL;
 
 	blkid_reset_probe(pr);
 	blkid_probe_reset_buffers(pr);
@@ -925,7 +926,8 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
 	if (pr->size <= 1440 * 1024 && !S_ISCHR(sb.st_mode))
 		pr->flags |= BLKID_FL_TINY_DEV;
 
-	if (S_ISBLK(sb.st_mode) && sysfs_devno_is_lvm_private(sb.st_rdev)) {
+	if (S_ISBLK(sb.st_mode) &&
+	    sysfs_devno_is_lvm_private(sb.st_rdev, &dm_uuid)) {
 		DBG(LOWPROBE, ul_debug("ignore private LVM device"));
 		pr->flags |= BLKID_FL_NOSCAN_DEV;
 	}
@@ -933,6 +935,7 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
 #ifdef CDROM_GET_CAPABILITY
 	else if (S_ISBLK(sb.st_mode) &&
 	    !blkid_probe_is_tiny(pr) &&
+	    !dm_uuid &&
 	    blkid_probe_is_wholedisk(pr) &&
 	    ioctl(fd, CDROM_GET_CAPABILITY, NULL) >= 0) {
 
@@ -940,6 +943,7 @@ int blkid_probe_set_device(blkid_probe pr, int fd,
 		cdrom_size_correction(pr);
 	}
 #endif
+	free(dm_uuid);
 
 	DBG(LOWPROBE, ul_debug("ready for low-probing, offset=%"PRIu64", size=%"PRIu64"",
 				pr->off, pr->size));
diff --git a/libblkid/src/verify.c b/libblkid/src/verify.c
index 412eb66ba..d84894b10 100644
--- a/libblkid/src/verify.c
+++ b/libblkid/src/verify.c
@@ -114,7 +114,7 @@ blkid_dev blkid_verify(blkid_cache cache, blkid_dev dev)
 		   (unsigned long)diff));
 #endif
 
-	if (sysfs_devno_is_lvm_private(st.st_rdev)) {
+	if (sysfs_devno_is_lvm_private(st.st_rdev, NULL)) {
 		blkid_free_dev(dev);
 		return NULL;
 	}