[PATCH] Btrfs-progs: mkfs, fix metadata corruption when using mixed mode

[fdmanana@xxxxxxxxxx]

From: Filipe Manana <fdmanana@xxxxxxxx>

When creating a filesystem with mixed block groups, we are creating two
space info objects to track used/reserved/pinned space, one only for data
and another one only for metadata.

This is making fstests test case generic/416 fail, with btrfs' check
reporting over an hundred errors about bad extents:

  (...)
  bad extent [17186816, 17190912), type mismatch with chunk
  bad extent [17195008, 17199104), type mismatch with chunk
  bad extent [17203200, 17207296), type mismatch with chunk
  (...)

Because, surprisingly, this results in block groups that do not have the
BTRFS_BLOCK_GROUP_DATA flag set but have data extents allocated in them.
This is a regression introduced in btrfs-progs v5.2.

So fix this by making sure we only create one space info object, for both
metadata and data, when mixed block groups are enabled.

Fixes: c31edf610cbe1e ("btrfs-progs: Fix false ENOSPC alert by tracking used space correctly")
Signed-off-by: Filipe Manana <fdmanana@xxxxxxxx>
---
 mkfs/main.c | 18 ++++++++++++------
 1 file changed, 12 insertions(+), 6 deletions(-)

diff --git a/mkfs/main.c b/mkfs/main.c
index 8dbec071..971cb395 100644
--- a/mkfs/main.c
+++ b/mkfs/main.c
@@ -64,18 +64,17 @@ static int create_metadata_block_groups(struct btrfs_root *root, int mixed,
 	struct btrfs_fs_info *fs_info = root->fs_info;
 	struct btrfs_trans_handle *trans;
 	struct btrfs_space_info *sinfo;
+	u64 flags = BTRFS_BLOCK_GROUP_METADATA;
 	u64 bytes_used;
 	u64 chunk_start = 0;
 	u64 chunk_size = 0;
 	int ret;
 
+	if (mixed)
+		flags |= BTRFS_BLOCK_GROUP_DATA;
+
 	/* Create needed space info to trace extents reservation */
-	ret = update_space_info(fs_info, BTRFS_BLOCK_GROUP_METADATA,
-				0, 0, &sinfo);
-	if (ret < 0)
-		return ret;
-	ret = update_space_info(fs_info, BTRFS_BLOCK_GROUP_DATA,
-				0, 0, &sinfo);
+	ret = update_space_info(fs_info, flags, 0, 0, &sinfo);
 	if (ret < 0)
 		return ret;
 
@@ -149,6 +148,13 @@ static int create_data_block_groups(struct btrfs_trans_handle *trans,
 	int ret = 0;
 
 	if (!mixed) {
+		struct btrfs_space_info *sinfo;
+
+		ret = update_space_info(fs_info, BTRFS_BLOCK_GROUP_DATA,
+					0, 0, &sinfo);
+		if (ret < 0)
+			return ret;
+
 		ret = btrfs_alloc_chunk(trans, fs_info,
 					&chunk_start, &chunk_size,
 					BTRFS_BLOCK_GROUP_DATA);
-- 
2.11.0