e2scrub_all: avoid scrubbing all devices when there is nothing to scrub

Running lsblk when there are no valid block devicse results in
generating all block devices as the list of devices to scrub; this
results in a lot of e2scrub_all failures.

Addresses-Debian-Bug: #929186

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

diff --git a/scrub/e2scrub_all.in b/scrub/e2scrub_all.in
index 7ee6531583cb923330c851ae72fa1ec9c269de95..abc237e426f3e356940a182672f9487475d359b1 100644 (file)
--- a/scrub/e2scrub_all.in
+++ b/scrub/e2scrub_all.in
@@ -103,8 +103,12 @@ fi
 
 # Find scrub targets, make sure we only do this once.
 ls_scan_targets() {
-       lsblk -o NAME,MOUNTPOINT,FSTYPE -P -n -p \
-             $(lvs -o lv_path --noheadings -S "lv_active=active,lv_role=public,lv_role!=snapshot,vg_free>${snap_size_mb}") | \
+    local devices=$(lvs -o lv_path --noheadings -S "lv_active=active,lv_role=public,lv_role!=snapshot,vg_free>${snap_size_mb}")
+
+    if [ -z "$devices" ]; then
+       return 0;
+    fi
+    lsblk -o NAME,MOUNTPOINT,FSTYPE -P -n -p $devices | \
            grep FSTYPE=\"ext\[234\]\" | while read vars ; do
                eval "${vars}"