Before this patch, btrfs-convert only rely on large enough initial
system/metadata chunk size to ensure no newer system/meta chunk will be
created.

But that's not safe enough. So add two new members in fs_info,
avoid_sys/meta_chunk_alloc flags to prevent any newer system or meta
chunks to be created before init_btrfs_v2().

BTW, old fs_info->system_allocs is not the same, as if set it to -1, it
will only force chunk tree blocks to be allocated from metadata.
Such wired design will be handled in later cleanup patchset, but not
now.

Signed-off-by: Qu Wenruo <[email protected]>
---
 btrfs-convert.c | 9 +++++++++
 ctree.h         | 2 ++
 extent-tree.c   | 9 +++++++++
 3 files changed, 20 insertions(+)

diff --git a/btrfs-convert.c b/btrfs-convert.c
index 1d09141..a81345d 100644
--- a/btrfs-convert.c
+++ b/btrfs-convert.c
@@ -2114,6 +2114,13 @@ static int init_btrfs_v2(struct btrfs_mkfs_config *cfg, 
ext2_filsys ext2_fs,
        int found_root = 0;
        int ret;
 
+       /*
+        * Don't alloc any metadata chunk, as we don't want any
+        * chunk allocated before all data chunks are inserted.
+        * Or we can screw up the chunk type.
+        */
+       fs_info->avoid_meta_chunk_alloc = 1;
+       fs_info->avoid_sys_chunk_alloc = 1;
        trans = btrfs_start_transaction(root, 1);
        BUG_ON(!trans);
        ret = btrfs_fix_block_accounting(trans, root);
@@ -2185,6 +2192,8 @@ static int init_btrfs_v2(struct btrfs_mkfs_config *cfg, 
ext2_filsys ext2_fs,
 
        ret = btrfs_commit_transaction(trans, root);
        BUG_ON(ret);
+       fs_info->avoid_meta_chunk_alloc = 0;
+       fs_info->avoid_sys_chunk_alloc = 0;
 err:
        return ret;
 }
diff --git a/ctree.h b/ctree.h
index 6e3e919..41b5e8f 100644
--- a/ctree.h
+++ b/ctree.h
@@ -1015,6 +1015,8 @@ struct btrfs_fs_info {
        unsigned int quota_enabled:1;
        unsigned int suppress_check_block_errors:1;
        unsigned int ignore_fsid_mismatch:1;
+       unsigned int avoid_meta_chunk_alloc:1;
+       unsigned int avoid_sys_chunk_alloc:1;
 
        int (*free_extent_hook)(struct btrfs_trans_handle *trans,
                                struct btrfs_root *root,
diff --git a/extent-tree.c b/extent-tree.c
index a2f8fee..c0b4442 100644
--- a/extent-tree.c
+++ b/extent-tree.c
@@ -1904,6 +1904,15 @@ static int do_chunk_alloc(struct btrfs_trans_handle 
*trans,
            thresh)
                return 0;
 
+       /*
+        * Avoid allocate any chunk forbit by fs_info
+        */
+       if (extent_root->fs_info->avoid_meta_chunk_alloc &&
+           (flags & BTRFS_BLOCK_GROUP_METADATA))
+               return 0;
+       if (extent_root->fs_info->avoid_sys_chunk_alloc &&
+           (flags & BTRFS_BLOCK_GROUP_SYSTEM))
+               return 0;
        ret = btrfs_alloc_chunk(trans, extent_root, &start, &num_bytes,
                                space_info->flags);
        if (ret == -ENOSPC) {
-- 
2.6.2

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