transposefs: Only autosave-xfs for much larger filesystems

overlay.d/05core/usr/lib/dracut/modules.d/40ignition-ostree/ignition-ostree-transposefs.sh

@@ -139,17 +139,24 @@ should_autosave_rootfs() {
         return
     fi
     local agcount
+    # This runs xfs_info on the unmounted filesystem, because mounting an
+    # XFS filesystem that has grown an excessive number of allocation groups
+    # can be very slow.
     eval $(xfs_info "${root_part}" | grep -o 'agcount=[0-9]*')
-    # Semi-arbitrarily chosen: this is roughly ~64G currently (based on initial
-    # ag sizing at build time) which seems like a good rootfs size at which to
-    # discriminate between "throwaway/short-lived systems" and "long-running
-    # workload systems". It's not like XFS performance is way worse at 128.
-    if [ "$agcount" -lt 128 ]; then
-        echo "Filesystem agcount is $agcount; skipping" >&2
+    # This is roughly ~700GiB currently (based on initial ag sizing at build time)
+    # which ensures we grow only on "large" root filesystems.
+    # Specifically for e.g. OpenShift, this ensures we don't reprovision on default
+    # worker node root filesystems.
+    local threshold
+    threshold=400
+    if [ "$agcount" -lt "${threshold}" ]; then
+        echo "autosave-xfs: ${root_part} agcount=$agcount is lower than threshold=${threshold}" >&2
         echo 0
         return
+    else
+        echo "autosave-xfs: ${root_part} agcount=$agcount meets threshold=${threshold}" >&2
+        echo 1
     fi
-    echo 1
 }
 
 ensure_zram_dev() {

tests/kola/root-reprovision/autosave-xfs/test.sh

@@ -2,15 +2,16 @@
 ## kola:
 ##   # This test reprovisions the rootfs automatically.
 ##   tags: "platform-independent reprovision"
-##   # Trigger automatic XFS reprovisioning
-##   minDisk: 100
+##   # Trigger automatic XFS reprovisioning (heuristic)
+##   minDisk: 1000
 ##   # Root reprovisioning requires at least 4GiB of memory.
 ##   minMemory: 4096
 ##   # This test includes a lot of disk I/O and needs a higher
 ##   # timeout value than the default.
 ##   timeoutMin: 15
 ##   description: Verify the root reprovision with XFS
 ##     on large disk triggers autosaved.
+##     This test is meant to cover ignition-ostree-transposefs-autosave-xfs.service
 
 set -xeuo pipefail
 
@@ -20,10 +21,13 @@ set -xeuo pipefail
 if [ ! -f /run/ignition-ostree-autosaved-xfs.stamp ]; then
     fatal "expected autosaved XFS"
 fi
+# Verify we printed something about the agcount
+journalctl -u ignition-ostree-transposefs-autosave-xfs.service --grep=agcount
 ok "autosaved XFS on large disk"
 
 eval $(xfs_info / | grep -o 'agcount=[0-9]*')
-if [ "$agcount" -gt 4 ]; then
-    fatal "expected agcount of at most 4, got ${agcount}"
+expected=4
+if [ "$agcount" -gt "$expected" ]; then
+    fatal "expected agcount of at most ${expected}, got ${agcount}"
 fi
 ok "low agcount on large disk"

tests/kola/root-reprovision/luks/autosave-xfs/test.sh

@@ -10,9 +10,10 @@
 ##   # timeout value than the default.
 ##   timeoutMin: 15
 ##   # Trigger automatic XFS reprovisioning
-##   minDisk: 100
+##   minDisk: 1000
 ##   description: Verify the root reprovision with XFS and TPM
 ##     on large disk triggers autosaved.
+##     This test is meant to cover ignition-ostree-transposefs-autosave-xfs.service
 
 set -xeuo pipefail
 
@@ -27,8 +28,9 @@ if [ -z "${AUTOPKGTEST_REBOOT_MARK:-}" ]; then
     ok "autosaved XFS on large disk"
 
     eval $(xfs_info / | grep -o 'agcount=[0-9]*')
-    if [ "$agcount" -gt 4 ]; then
-        fatal "expected agcount of at most 4, got ${agcount}"
+    expected=4
+    if [ "$agcount" -gt "${expected}" ]; then
+        fatal "expected agcount of at most ${expected}, got ${agcount}"
     fi
     ok "low agcount on large disk"
 fi