From e4532fdfa44e02fc36f1757a2754769a64c6587f Mon Sep 17 00:00:00 2001
From: Andrew Cady <d@jerkface.net>
Date: Fri, 29 Apr 2016 02:05:18 -0400
Subject: samizdat-eject will wait for btrfs before final copy

---
 samizdat-eject.sh | 87 ++++++++++++++++++++++++++++++++++---------------------
 1 file changed, 54 insertions(+), 33 deletions(-)

diff --git a/samizdat-eject.sh b/samizdat-eject.sh
index bfd8e1c..d95a49d 100755
--- a/samizdat-eject.sh
+++ b/samizdat-eject.sh
@@ -5,6 +5,48 @@ die()
     exit 1
 }
 
+btrfs_subdevices()
+{
+    local mountpoint="$1"
+    btrfs filesystem show "$mountpoint" | sed -ne 's/^[ \t]*devid.* path //p'
+}
+
+btrfs_subdevice_count()
+{
+    btrfs_subdevices "$1" | wc -l
+}
+
+remove()
+{
+    for dev; do
+        (set -x; btrfs device remove "$dev" /)
+        dmsetup remove "$dev" 2>/dev/null
+        losetup -D
+    done
+}
+
+dm_name()
+{
+    dmsetup info "$1" | sed -ne 's/^Name: *//p'
+}
+
+md_ready()
+{
+    local mountpoint="$1" count dev
+    count=$(mdadm_subdevices /dev/md55|wc -l)
+    [ "$count" = 1 ] || return
+    dev=$(mdadm_subdevices /dev/md55)
+    [ "$(dm_name "$dev")" = samizdatiso ]
+}
+
+copy()
+{
+    temp_target=$(mktemp --tmpdir=/outerfs)
+    mdadm_copy_eject_crypt /dev/md55 "$temp_target"
+}
+
+. mdadm-dup.sh || exit 1
+
 target=$1
 
 if [ ! "$target" ] && mountpoint -q /srv && [ ! -e /srv/samizdat.iso ]; then
@@ -14,20 +56,10 @@ fi
 [ "$target" ] || die "Usage: $0 <target filename>"
 [ ! -e "$target" ] || die "Error: file exists: $target"
 
-if mountpoint -q /outerfs; then
-    temp_target=$(mktemp --tmpdir=/outerfs)
-else
+if ! mountpoint -q /outerfs; then
     die "Error: /outerfs is not a mountpoint.  Please mount a safe filesystem to temporarily store the ISO on /outerfs"
 fi
 
-. mdadm-dup.sh || exit 1
-
-btrfs_subdevices()
-{
-    local mountpoint="$1"
-    btrfs filesystem show "$mountpoint" | sed -ne 's/^[ \t]*devid.* path //p'
-}
-
 devices=$(btrfs_subdevices /) || exit 1
 
 set --
@@ -41,31 +73,20 @@ for dev in $devices; do
 done
 [ "$seen" ] || set -- # avoid messing up someone's btrfs!
 
-copy()
-{
-    mdadm_copy_eject_crypt /dev/md55 "$temp_target" &&
-        mdadm_copy_eject /dev/md55 "$target".part &&
-        mv "$target".part "$target"
-}
 
-remove()
-{
-    for dev; do
-        (set -x; btrfs device remove "$dev" /)
-        dmsetup remove "$dev" 2>/dev/null
-        losetup -D
-    done
-}
 
-# Doing the mdadm copy before removing the devices means our filesystem includes
-# devices that are ultimately backed by files ON THE SAME FILESYSTEM. As such, it
-# might conceivably put btrfs into a deadlock of some kind.
 
-# If it turns out this doesn't work, the order can be reversed. This will
-# perform the read IO twice, though, almost doubling the total installation
-# time.
 
-copy & remove "$@"
 
-set -x
+if ! md_ready; then
+    copy &
+fi
+
+remove "$@"
+
 wait
+
+if [ "$(btrfs_subdevice_count /)" = 1 ] && md_ready; then
+    mdadm_copy_eject /dev/md55 "$target".part &&
+        mv "$target".part "$target"
+fi
-- 
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