tests: add fast commit recovery tests

Add j_recover_fast_commit test that ensure that e2fsck is able to
recover a disk from fast commit log.

Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com>
Signed-off-by: Theodore Ts'o <tytso@mit.edu>

tests/j_recover_fast_commit/commands

@@ -0,0 +1,4 @@
+ls
+ls a/
+ex a/new
+ex a/data

tests/j_recover_fast_commit/expect

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+Pass 1: Checking inodes, blocks, and sizes
+Pass 2: Checking directory structure
+Pass 3: Checking directory connectivity
+Pass 4: Checking reference counts
+Pass 5: Checking group summary information
+test_filesys: 14/256 files (14.3% non-contiguous), 1365/2048 blocks
+Exit status is 0
+debugfs: ls
+ 2  (12) .    2  (12) ..    11  (20) lost+found    12  (968) a   
+debugfs: ls a/
+ 12  (12) .    2  (12) ..    13  (12) data    14  (976) new   
+debugfs: ex a/new
+Level Entries       Logical      Physical Length Flags
+ 0/ 0   1/  1     0 -     0  1107 -  1107      1 
+debugfs: ex a/data
+Level Entries       Logical      Physical Length Flags
+ 0/ 1   1/  1     0 -   255  1618            256
+ 1/ 1   1/  5     0 -    15  1619 -  1634     16 
+ 1/ 1   2/  5    16 -    31  1601 -  1616     16 
+ 1/ 1   3/  5    32 -    63  1985 -  2016     32 
+ 1/ 1   4/  5    64 -   127  1537 -  1600     64 
+ 1/ 1   5/  5   128 -   255  1793 -  1920    128 

tests/j_recover_fast_commit/script

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+#!/bin/bash
+
+FSCK_OPT=-fy
+IMAGE=$test_dir/image.gz
+CMDS=$test_dir/commands
+
+gunzip < $IMAGE > $TMPFILE
+
+# Run fsck to fix things?
+EXP=$test_dir/expect
+OUT=$test_name.log
+
+cp $TMPFILE /tmp/debugthis
+$FSCK $FSCK_OPT -E journal_only -N test_filesys $TMPFILE 2>/dev/null | head -n 1000 | tail -n +2 > $OUT
+echo "Exit status is $?" >> $OUT
+
+$DEBUGFS -f $CMDS $TMPFILE >> $OUT 2>/dev/null
+
+# Figure out what happened
+if cmp -s $EXP $OUT; then
+	echo "$test_name: $test_description: ok"
+	touch $test_name.ok
+else
+	echo "$test_name: $test_description: failed"
+	diff -u $EXP $OUT >> $test_name.failed
+fi