partname: Introduce fstools_partname_fallback_scan option

Some device may contains a GPT partition named rootfs_data that may
not be suitable.
To save from regression with old implementation that doesn't use
fstools_ignore_partname to explicitly say that that parname scan
should be ignored, make explicit that scanning each partition should
be done by providing fstools_partname_fallback_scan=1 and skip partname
scan in every other case.

Fixes: e9b59f063bb3 ("partname: Ignore root=PARTUUID...")
Tested-by: Dirk Buchwalder <buchwalder@posteo.de>
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>

diff --git a/libfstools/partname.c b/libfstools/partname.c
index 9c27015643ad683620aa9c44ad167616a5f56fb3..f42322a49d5ba2d730d532c79d4475bc71ba2186 100644 (file)
--- a/libfstools/partname.c
+++ b/libfstools/partname.c
@@ -133,6 +133,19 @@ static struct volume *partname_volume_find(char *name)
                /* find partition on same device as rootfs */
                snprintf(ueventgstr, sizeof(ueventgstr), "%s/%s/*/uevent", block_dir_name, rootdev);
        } else {
+               /*
+                * Some device may contains a GPT partition named rootfs_data that may not be suitable.
+                * To save from regression with old implementation that doesn't use fstools_ignore_partname to
+                * explicitly say that that parname scan should be ignored, make explicit that scanning each
+                * partition should be done by providing fstools_partname_fallback_scan=1 and skip partname scan
+                * in every other case.
+                */
+               if (!get_var_from_file("/proc/cmdline", "fstools_partname_fallback_scan", rootparam, sizeof(rootparam)))
+                       return NULL;
+
+               if (!strcmp("1", rootparam))
+                       return NULL;
+
                /* no useful 'root=' kernel cmdline parameter, find on any block device */
                snprintf(ueventgstr, sizeof(ueventgstr), "%s/*/uevent", block_dir_name);
        }