Do orphaned inode extent freeing in chunks

Fix an issue where the final freeing of extents for unlinked files
could trigger spurious hung task timeout warnings. Instead of holding the
scoutfs inode lock for the entire duration of extent freeing, release and
reacquire the lock every time the transaction sequence number changes.

This is only used in the evict and orphan inode cleanup paths; truncate
and release continue to free during a single lock hold.

Remove the hung_task_timeout_secs workaround from the large-fragmented-free
test script.

Signed-off-by: Chris Kirby <ckirby@versity.com>

tests/golden/large-fragmented-free

@@ -1,4 +1,3 @@
-== setting longer hung task timeout
 == creating fragmented extents
 == unlink file with moved extents to free extents per block
 == cleanup

tests/tests/large-fragmented-free.sh

@@ -10,30 +10,6 @@ EXTENTS_PER_BTREE_BLOCK=600
 EXTENTS_PER_LIST_BLOCK=8192
 FREED_EXTENTS=$((EXTENTS_PER_BTREE_BLOCK * EXTENTS_PER_LIST_BLOCK))
 
-#
-# This test specifically creates a pathologically sparse file that will
-# be as expensive as possible to free.  This is usually fine on
-# dedicated or reasonable hardware, but trying to run this in
-# virtualized debug kernels can take a very long time.  This test is
-# about making sure that the server doesn't fail, not that the platform
-# can handle the scale of work that our btree formats happen to require
-# while execution is bogged down with use-after-free memory reference
-# tracking.  So we give the test a lot more breathing room before
-# deciding that its hung.
-#
-echo "== setting longer hung task timeout"
-if [ -w /proc/sys/kernel/hung_task_timeout_secs ]; then
-	secs=$(cat /proc/sys/kernel/hung_task_timeout_secs)
-	test "$secs" -gt 0 || \
-		t_fail "confusing value '$secs' from /proc/sys/kernel/hung_task_timeout_secs"
-	restore_hung_task_timeout()
-	{
-		echo "$secs" > /proc/sys/kernel/hung_task_timeout_secs
-	}
-	trap restore_hung_task_timeout EXIT
-	echo "$((secs * 5))" > /proc/sys/kernel/hung_task_timeout_secs
-fi
-
 echo "== creating fragmented extents"
 fragmented_data_extents $FREED_EXTENTS $EXTENTS_PER_BTREE_BLOCK "$T_D0/alloc" "$T_D0/move"