Merge tag 'for-5.12-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux

Pull btrfs fixes from David Sterba:
 "There are still regressions being found and fixed in the zoned mode
  and subpage code, the rest are fixes for bugs reported by users.

  Regressions:

   - subpage block support:
      - readahead works on the proper block size
      - fix last page zeroing

   - zoned mode:
      - linked list corruption for tree log

  Fixes:

   - qgroup leak after falloc failure

   - tree mod log and backref resolving:
      - extent buffer cloning race when resolving backrefs
      - pin deleted leaves with active tree mod log users

   - drop debugging flag from slab cache"

* tag 'for-5.12-rc3-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
  btrfs: always pin deleted leaves when there are active tree mod log users
  btrfs: fix race when cloning extent buffer during rewind of an old root
  btrfs: fix slab cache flags for free space tree bitmap
  btrfs: subpage: make readahead work properly
  btrfs: subpage: fix wild pointer access during metadata read failure
  btrfs: zoned: fix linked list corruption after log root tree allocation failure
  btrfs: fix qgroup data rsv leak caused by falloc failure
  btrfs: track qgroup released data in own variable in insert_prealloc_file_extent
  btrfs: fix wrong offset to zero out range beyond i_size

1 files changed, 22 insertions, 1 deletions

diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 78ad31a59e59..36a3c973fda1 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3323,6 +3323,7 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
 
 	if (last_ref && btrfs_header_generation(buf) == trans->transid) {
 		struct btrfs_block_group *cache;
+		bool must_pin = false;
 
 		if (root->root_key.objectid != BTRFS_TREE_LOG_OBJECTID) {
 			ret = check_ref_cleanup(trans, buf->start);
@@ -3340,7 +3341,27 @@ void btrfs_free_tree_block(struct btrfs_trans_handle *trans,
 			goto out;
 		}
 
-		if (btrfs_is_zoned(fs_info)) {
+		/*
+		 * If this is a leaf and there are tree mod log users, we may
+		 * have recorded mod log operations that point to this leaf.
+		 * So we must make sure no one reuses this leaf's extent before
+		 * mod log operations are applied to a node, otherwise after
+		 * rewinding a node using the mod log operations we get an
+		 * inconsistent btree, as the leaf's extent may now be used as
+		 * a node or leaf for another different btree.
+		 * We are safe from races here because at this point no other
+		 * node or root points to this extent buffer, so if after this
+		 * check a new tree mod log user joins, it will not be able to
+		 * find a node pointing to this leaf and record operations that
+		 * point to this leaf.
+		 */
+		if (btrfs_header_level(buf) == 0) {
+			read_lock(&fs_info->tree_mod_log_lock);
+			must_pin = !list_empty(&fs_info->tree_mod_seq_list);
+			read_unlock(&fs_info->tree_mod_log_lock);
+		}
+
+		if (must_pin || btrfs_is_zoned(fs_info)) {
 			btrfs_redirty_list_add(trans->transaction, buf);
 			pin_down_extent(trans, cache, buf->start, buf->len, 1);
 			btrfs_put_block_group(cache);