rear/rear-save-lvm-poolmetadatasize-RHEL-6984.patch

From e7b84271536782fbc8673ef4573e155e1dfa850e Mon Sep 17 00:00:00 2001
From: pcahyna <pcahyna@users.noreply.github.com>
Date: Wed, 1 Nov 2023 12:53:33 +0100
Subject: [PATCH] Merge pull request #3061 from
 pcahyna/save-lvm-poolmetadatasize

Save LVM pool metadata volume size in disk layout
---
 .../layout/save/GNU/Linux/220_lvm_layout.sh   | 39 ++++++++++++-------
 1 file changed, 24 insertions(+), 15 deletions(-)

diff --git a/usr/share/rear/layout/save/GNU/Linux/220_lvm_layout.sh b/usr/share/rear/layout/save/GNU/Linux/220_lvm_layout.sh
index f21845df9..42f0e4126 100644
--- a/usr/share/rear/layout/save/GNU/Linux/220_lvm_layout.sh
+++ b/usr/share/rear/layout/save/GNU/Linux/220_lvm_layout.sh
@@ -18,7 +18,7 @@ local already_processed_lvs=()
 local lv_layout_supported lvs_fields
 local origin lv vg
 local layout modules
-local thinpool chunksize stripes stripesize segmentsize
+local thinpool chunksize stripes stripesize segmentsize poolmetadatasize
 local kval infokval
 local lvs_exit_code
 
@@ -130,7 +130,7 @@ local lvs_exit_code
             echo "# Skipping PV $pdev that is not part of a valid VG (VG '$vgrp' empty or more than one word):"
             contains_visible_char "$vgrp" || vgrp='<missing_VG>'
             echo "# lvmdev /dev/$vgrp $pdev $uuid $size"
-            # Continue with the next line in the output of "lvm pvdisplay -c"
+            # Continue with the next line in the output of "lvm pvdisplay -C"
             continue
         fi
         # With the above example the output is:
@@ -138,10 +138,10 @@ local lvs_exit_code
         echo "lvmdev /dev/$vgrp $pdev $uuid $size"
 
     done
-    # Check the exit code of "lvm pvdisplay -c"
-    # in the "lvm pvdisplay -c | while read line ; do ... done" pipe:
+    # Check the exit code of "lvm pvdisplay -C"
+    # in the "lvm pvdisplay -C ... | while read line ; do ... done" pipe:
     pvdisplay_exit_code=${PIPESTATUS[0]}
-    test $pvdisplay_exit_code -eq 0 || Error "LVM command 'lvm pvdisplay -c' failed with exit code $pvdisplay_exit_code"
+    test $pvdisplay_exit_code -eq 0 || Error "LVM command 'lvm pvdisplay -C ... -o pv_name,vg_name,pv_size,pv_uuid' failed with exit code $pvdisplay_exit_code"
 
     # Get the volume group configuration:
     # Format: lvmgrp <volume_group> <extentsize> [<size(extents)>] [<size(bytes)>]
@@ -200,17 +200,17 @@ local lvs_exit_code
 
     # Specify the fields for the lvs command depending on whether or not the 'lv_layout' field is supported:
     if is_true $lv_layout_supported ; then
-        lvs_fields="origin,lv_name,vg_name,lv_size,lv_layout,pool_lv,chunk_size,stripes,stripe_size,seg_size"
+        lvs_fields="origin,lv_name,vg_name,lv_size,lv_layout,pool_lv,chunk_size,stripes,stripe_size,seg_size,lv_metadata_size"
     else
         # Use the 'modules' field as fallback replacement when the 'lv_layout' field is not supported:
-        lvs_fields="origin,lv_name,vg_name,lv_size,modules,pool_lv,chunk_size,stripes,stripe_size,seg_size"
+        lvs_fields="origin,lv_name,vg_name,lv_size,modules,pool_lv,chunk_size,stripes,stripe_size,seg_size,lv_metadata_size"
     fi
 
     # Example output of "lvs --separator=':' --noheadings --units b --nosuffix -o $lvs_fields"
-    # with lvs_fields="origin,lv_name,vg_name,lv_size,lv_layout,pool_lv,chunk_size,stripes,stripe_size,seg_size"
+    # with lvs_fields="origin,lv_name,vg_name,lv_size,lv_layout,pool_lv,chunk_size,stripes,stripe_size,seg_size,lv_metadata_size"
     # i.e. when the 'lv_layout' field is supported:
-    #   :root:system:19927138304:linear::0:1:0:19927138304
-    #   :swap:system:1535115264:linear::0:1:0:1535115264
+    #   :root:system:19927138304:linear::0:1:0:19927138304:
+    #   :swap:system:1535115264:linear::0:1:0:1535115264:
     # There are two leading blanks in the output (at least on SLES12-SP4 with LVM 2.02.180).
     lvm lvs --separator=':' --noheadings --units b --nosuffix -o $lvs_fields | while read line ; do
 
@@ -261,14 +261,23 @@ local lvs_exit_code
         # With the above example segmentsize=19927138304 and segmentsize=1535115264
         segmentsize="$( echo "$line" | awk -F ':' '{ print $10 }' )"
 
-        # TODO: Explain what that code is meant to do.
-        # In particular a more explanatory variable name than 'kval' might help.
-        # In 110_include_lvm_code.sh there is a comment what 'kval' means there
-        #   # kval: "key:value" pairs, separated by spaces
-        # so probably 'kval' means the same here, but what is 'infokval'?
+        # With the above example poolmetadatasize=""
+        poolmetadatasize="$( echo "$line" | awk -F ':' '{ print $11 }' )"
+
+        # kval is a string of space-separated key:value pairs. Key names are chosen to represent
+        # long options to lvcreate, and value will be the parameter for each long option.
+        # e.g. "chunksize:${chunksize}b" will eventually become a --chunksize=${chunksize}b
+        # argument to lvcreate.
+        # This way 110_include_lvm_code.sh which constructs the arguments to lvcreate
+        # can be kept generic and does not need to be updated every time an argument is added,
+        # as long as the argument can follow this generic scheme.
+        # infokval are key:value pairs that are not used when restoring the layout
+        # and are kept in disklayout.conf only as comments for information
+        # (because the setting is not easy or desirable to preserve).
         kval=""
         infokval=""
         [ -z "$thinpool" ] || kval="${kval:+$kval }thinpool:$thinpool"
+        [ -z "$poolmetadatasize" ] || kval="${kval:+$kval }poolmetadatasize:${poolmetadatasize}b"
         [ $chunksize -eq 0 ] || kval="${kval:+$kval }chunksize:${chunksize}b"
         [ $stripesize -eq 0 ] || kval="${kval:+$kval }stripesize:${stripesize}b"
         [ $segmentsize -eq $size ] || infokval="${infokval:+$infokval }segmentsize:${segmentsize}b"
-- 
2.43.0