libbtrfsutil: always build libbtrfsutil.so.$MAJOR

[platform/upstream/btrfs-progs.git] / free-space-cache.c

diff --git a/free-space-cache.c b/free-space-cache.c
index f933f9f..9b83a71 100644 (file)
--- a/free-space-cache.c
+++ b/free-space-cache.c
@@ -438,7 +438,8 @@ int load_free_space_cache(struct btrfs_fs_info *fs_info,
        struct btrfs_path *path;
        u64 used = btrfs_block_group_used(&block_group->item);
        int ret = 0;
-       int matched;
+       u64 bg_free;
+       s64 diff;
 
        path = btrfs_alloc_path();
        if (!path)
@@ -448,18 +449,33 @@ int load_free_space_cache(struct btrfs_fs_info *fs_info,
                                      block_group->key.objectid);
        btrfs_free_path(path);
 
-       matched = (ctl->free_space == (block_group->key.offset - used -
-                                      block_group->bytes_super));
-       if (ret == 1 && !matched) {
-               __btrfs_remove_free_space_cache(ctl);
+       bg_free = block_group->key.offset - used - block_group->bytes_super;
+       diff = ctl->free_space - bg_free;
+       if (ret == 1 && diff) {
                fprintf(stderr,
-                      "block group %llu has wrong amount of free space\n",
-                      block_group->key.objectid);
+                      "block group %llu has wrong amount of free space, free space cache has %llu block group has %llu\n",
+                      block_group->key.objectid, ctl->free_space, bg_free);
+               __btrfs_remove_free_space_cache(ctl);
+               /*
+                * Due to btrfs_reserve_extent() can happen out of a
+                * transaction, but all btrfs_release_extent() happens inside
+                * a transaction, so under heavy race it's possible that free
+                * space cache has less free space, and both kernel just discard
+                * such cache. But if we find some case where free space cache
+                * has more free space, this means under certain case such
+                * cache can be loaded and cause double allocate.
+                *
+                * Detect such possibility here.
+                */
+               if (diff > 0)
+                       error(
+"free space cache has more free space than block group item, this could leads to serious corruption, please contact btrfs developers");
                ret = -1;
        }
 
        if (ret < 0) {
-               ret = 0;
+               if (diff <= 0)
+                       ret = 0;
 
                fprintf(stderr,
                       "failed to load free space cache for block group %llu\n",