From 6cb0239e7eb67d939a299282e0ade7b37e7c0726 Mon Sep 17 00:00:00 2001
From: Vitaliy Filippov <vitalif@yourcmc.ru>
Date: Thu, 26 Dec 2013 13:00:03 +0000
Subject: [PATCH] adjust algorithm, add inode map impl based on reallocated
 "vector"

---
 realloc-inodes.c | 80 ++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 74 insertions(+), 6 deletions(-)

diff --git a/realloc-inodes.c b/realloc-inodes.c
index 08c9987..69818c3 100644
--- a/realloc-inodes.c
+++ b/realloc-inodes.c
@@ -3,16 +3,22 @@
  *
  * In theory it shouldn't be that hard:
  * 1) If shrinking:
- * 1.1) move inodes so that the end of inode table is empty
- * 1.2) mark some blocks that belonged to inode table as free
+ * 1.1) mark the end of each inode table as reserved (to make sure the inode allocator won't allocate it)
+ * 1.2) if there were some inodes, move them away:
+ * 1.2.1) allocate a new place for each inode, copy it there
+ * 1.2.2) remember the old->new inode number mapping
+ * 1.3) mark some blocks that belonged to inode table as free
  * 2) If growing:
- * 2.1) move data blocks so there is enough space reserved for new inode table
- * 2.2) mark some blocks that should belong to inode table as occupied
+ * 2.1) check all extra blocks that will be occupied by the growing inode tables,
+ *      mark them as occupied if there are free ()
+ * 2.2) move data away from 'extra blocks' that were occupied
  * 3) Change all inode numbers in directory entries so that
  *    new_num = (old_num/old_inodes_per_group)*new_inodes_per_group + (old_num%inodes_per_group)
+ *    also translate old->new inode numbers remembered at (1.2.2)
  * 4) Change superblock: s_inodes_count, s_free_inodes_count, s_inodes_per_group
  * 5) Change block group descriptors: bg_inode_table_(lo,hi), bg_free_inodes_count_(lo,hi),
  *    bg_inode_bitmap_csum_(lo,hi), bg_itable_unused_(lo,hi)
+ * 6) If flex_bg is enabled, move parts of old inode tables so they are consecutive again
  *
  * This is a destructive process involving metadata change so it would be good if
  * we could first write a file containing all necessary changes, then backup all
@@ -29,11 +35,73 @@
 #include <sys/time.h>
 #include <errno.h>
 
-#include "ext2fs/ext2_fs.h"
-#include "ext2fs/ext2fs.h"
+#include <ext2fs/ext2_fs.h>
+#include <ext2fs/ext2fs.h>
 
 #define _(a) (a)
 
+typedef struct
+{
+    __u32 *inode_map, inode_map_size, inode_map_alloc;
+} realloc_data;
+
+void add_inode_map(realloc_data *rd, __u32 old, __u32 new)
+{
+    if (!old || !new)
+    {
+        return;
+    }
+    if (2*rd->inode_map_size >= rd->inode_map_alloc)
+    {
+        rd->inode_map_alloc += 1024;
+        rd->inode_map = realloc(rd->inode_map, sizeof(__u32) * rd->inode_map_alloc);
+    }
+    rd->inode_map[rd->inode_map_size*2] = old;
+    rd->inode_map[rd->inode_map_size*2+1] = new;
+    rd->inode_map_size++;
+}
+
+int compare_inode_map(const void *a, const void *b)
+{
+    return *((__u32*)a) - *((__u32*)b);
+}
+
+void sort_inode_map(realloc_data *rd)
+{
+    if (!rd->inode_map)
+    {
+        return;
+    }
+    qsort(rd->inode_map, rd->inode_map_size, sizeof(__u32)*2, compare_inode_map);
+}
+
+__u32 search_inode_map(realloc_data *rd, __u32 old)
+{
+    __u32 start = 0, end = rd->inode_map_size, cur, cur_old;
+    if (!rd->inode_map)
+    {
+        return 0;
+    }
+    while (end-start > 1)
+    {
+        cur = (start+end)>>1;
+        cur_old = rd->inode_map[cur<<1];
+        if (cur < old)
+        {
+            start = cur+1;
+        }
+        else if (cur > old)
+        {
+            end = cur;
+        }
+        else
+        {
+            return rd->inode_map[(cur<<1)+1];
+        }
+    }
+    return 0;
+}
+
 const char *program_name = "realloc-inodes";
 
 int change_inode_numbers(ext2_ino_t dir, int entry,