From 90e0e0cfe7d90bb9b8cc4a8eb9225266b1622453 Mon Sep 17 00:00:00 2001
From: "Richard W.M. Jones" <rjones@redhat.com>
Date: Thu, 15 Apr 2021 16:52:36 +0100
Subject: [PATCH] v2v: Increase required free space in Windows to 100 MB

With an increasing number of drivers being installed in Windows the
existing limit (20 MB) was far too low.  In fact we found that a guest
with 63 MB of free space would sometimes run out of space.

This commit increases the required space to 100 MB for Windows.

There are also a couple of smaller fixes:

 - We now properly distinguish between / as a Linux boot drive,
   and Windows.

 - The error message has been improved to display MBs instead of bytes.

Reported-by: Ming Xie
Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1949147
(cherry picked from commit dfcf60c916a986a352938b432231a36558a3bc05)
---
 docs/virt-v2v.pod |  8 +++++++-
 v2v/v2v.ml        | 46 +++++++++++++++++++++++++---------------------
 2 files changed, 32 insertions(+), 22 deletions(-)

diff --git a/docs/virt-v2v.pod b/docs/virt-v2v.pod
index 50b0bc8e..4016c724 100644
--- a/docs/virt-v2v.pod
+++ b/docs/virt-v2v.pod
@@ -1288,7 +1288,7 @@ to perform the conversion.  Currently it checks:
 
 =over 4
 
-=item Linux root filesystem or Windows C<C:> drive
+=item Linux root filesystem
 
 Minimum free space: 20 MB
 
@@ -1299,6 +1299,12 @@ Minimum free space: 50 MB
 This is because we need to build a new initramfs for some Enterprise
 Linux conversions.
 
+=item Windows C<C:> drive
+
+Minimum free space: 100 MB
+
+We may have to copy in many virtio drivers and guest agents.
+
 =item Any other mountable filesystem
 
 Minimum free space: 10 MB
diff --git a/v2v/v2v.ml b/v2v/v2v.ml
index 1f8d0138..bde51885 100644
--- a/v2v/v2v.ml
+++ b/v2v/v2v.ml
@@ -108,7 +108,7 @@ let rec main () =
   let inspect = Inspect_source.inspect_source cmdline.root_choice g in
 
   let mpstats = get_mpstats g in
-  check_guest_free_space mpstats;
+  check_guest_free_space inspect mpstats;
 
   (* Estimate space required on target for each disk.  Note this is a max. *)
   (match conversion_mode with
@@ -377,27 +377,28 @@ and print_mpstat chan { mp_dev = dev; mp_path = path;
  *
  * Also make sure filesystems have available inodes. (RHBZ#1764569)
  *)
-and check_guest_free_space mpstats =
+and check_guest_free_space inspect mpstats =
   message (f_"Checking for sufficient free disk space in the guest");
 
   (* Check whether /boot has its own mount point. *)
   let has_boot = List.exists (fun { mp_path } -> mp_path = "/boot") mpstats in
+  let is_windows = inspect.i_distro = "windows" in
 
-  let needed_bytes_for_mp = function
-    | "/boot"
-    | "/" when not has_boot ->
-      (* We usually regenerate the initramfs, which has a
-       * typical size of 20-30MB.  Hence:
-       *)
-      50_000_000L
-    | "/" ->
-      (* We may install some packages, and they would usually go
-       * on the root filesystem.
-       *)
-      20_000_000L
-    | _ ->
-      (* For everything else, just make sure there is some free space. *)
-      10_000_000L
+  let needed_megabytes_for_mp = function
+    (* We usually regenerate the initramfs, which has a
+     * typical size of 20-30MB.  Hence:
+     *)
+    | "/boot" | "/" when not has_boot && not is_windows -> 50
+    (* We may install some packages, and they would usually go
+     * on the root filesystem.
+     *)
+    | "/" when not is_windows -> 20
+    (* Windows requires copying in many device drivers and possibly
+     * guest agents, so we need more space.  (RHBZ#1949147).
+     *)
+    | "/" (* when is_windows *) -> 100
+    (* For everything else, just make sure there is some free space. *)
+    | _ -> 10
   in
 
   (* Reasonable headroom for conversion operations. *)
@@ -407,10 +408,13 @@ and check_guest_free_space mpstats =
     fun { mp_path; mp_statvfs = { G.bfree; bsize; files; ffree } } ->
       (* bfree = free blocks for root user *)
       let free_bytes = bfree *^ bsize in
-      let needed_bytes = needed_bytes_for_mp mp_path in
-      if free_bytes < needed_bytes then
-        error (f_"not enough free space for conversion on filesystem ‘%s’.  %Ld bytes free < %Ld bytes needed")
-          mp_path free_bytes needed_bytes;
+      let needed_megabytes = needed_megabytes_for_mp mp_path in
+      let needed_bytes = Int64.of_int needed_megabytes *^ 1024L *^ 1024L in
+      if free_bytes < needed_bytes then (
+        let mb i = Int64.to_float i /. 1024. /. 1024. in
+        error (f_"not enough free space for conversion on filesystem ‘%s’.  %.1f MB free < %d MB needed")
+          mp_path (mb free_bytes) needed_megabytes
+      );
       (* Not all the filesystems have inode counts. *)
       if files > 0L && ffree < needed_inodes then
         error (f_"not enough available inodes for conversion on filesystem ‘%s’.  %Ld inodes available < %Ld inodes needed")
-- 
2.18.4