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-rw-r--r--fs/btrfs/transaction.c24
1 files changed, 24 insertions, 0 deletions
diff --git a/fs/btrfs/transaction.c b/fs/btrfs/transaction.c
index 03de89b45f27..c43bbc7f623e 100644
--- a/fs/btrfs/transaction.c
+++ b/fs/btrfs/transaction.c
@@ -2000,6 +2000,27 @@ static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
}
+/*
+ * Add a pending snapshot associated with the given transaction handle to the
+ * respective handle. This must be called after the transaction commit started
+ * and while holding fs_info->trans_lock.
+ * This serves to guarantee a caller of btrfs_commit_transaction() that it can
+ * safely free the pending snapshot pointer in case btrfs_commit_transaction()
+ * returns an error.
+ */
+static void add_pending_snapshot(struct btrfs_trans_handle *trans)
+{
+ struct btrfs_transaction *cur_trans = trans->transaction;
+
+ if (!trans->pending_snapshot)
+ return;
+
+ lockdep_assert_held(&trans->fs_info->trans_lock);
+ ASSERT(cur_trans->state >= TRANS_STATE_COMMIT_START);
+
+ list_add(&trans->pending_snapshot->list, &cur_trans->pending_snapshots);
+}
+
int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
{
struct btrfs_fs_info *fs_info = trans->fs_info;
@@ -2073,6 +2094,8 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
enum btrfs_trans_state want_state = TRANS_STATE_COMPLETED;
+ add_pending_snapshot(trans);
+
spin_unlock(&fs_info->trans_lock);
refcount_inc(&cur_trans->use_count);
@@ -2163,6 +2186,7 @@ int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
* COMMIT_DOING so make sure to wait for num_writers to == 1 again.
*/
spin_lock(&fs_info->trans_lock);
+ add_pending_snapshot(trans);
cur_trans->state = TRANS_STATE_COMMIT_DOING;
spin_unlock(&fs_info->trans_lock);
wait_event(cur_trans->writer_wait,