4.8-stable review patch. If anyone has any objections, please let me know.
------------------ From: Jan Kara <j...@suse.cz> commit e03a9976afce6634826d56c33531dd10bb9a9166 upstream. Thomas has reported a lockdep splat hitting in add_transaction_credits(). The problem is that that function calls jbd2_might_wait_for_commit() while holding j_state_lock which is wrong (we do not really wait for transaction commit while holding that lock). Fix the problem by moving jbd2_might_wait_for_commit() into places where we are ready to wait for transaction commit and thus j_state_lock is unlocked. Fixes: 1eaa566d368b214d99cbb973647c1b0b8102a9ae Reported-by: Thomas Gleixner <t...@linutronix.de> Signed-off-by: Jan Kara <j...@suse.cz> Signed-off-by: Theodore Ts'o <ty...@mit.edu> Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org> --- fs/jbd2/transaction.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -159,6 +159,7 @@ static void wait_transaction_locked(jour read_unlock(&journal->j_state_lock); if (need_to_start) jbd2_log_start_commit(journal, tid); + jbd2_might_wait_for_commit(journal); schedule(); finish_wait(&journal->j_wait_transaction_locked, &wait); } @@ -182,8 +183,6 @@ static int add_transaction_credits(journ int needed; int total = blocks + rsv_blocks; - jbd2_might_wait_for_commit(journal); - /* * If the current transaction is locked down for commit, wait * for the lock to be released. @@ -214,6 +213,7 @@ static int add_transaction_credits(journ if (atomic_read(&journal->j_reserved_credits) + total > journal->j_max_transaction_buffers) { read_unlock(&journal->j_state_lock); + jbd2_might_wait_for_commit(journal); wait_event(journal->j_wait_reserved, atomic_read(&journal->j_reserved_credits) + total <= journal->j_max_transaction_buffers); @@ -238,6 +238,7 @@ static int add_transaction_credits(journ if (jbd2_log_space_left(journal) < jbd2_space_needed(journal)) { atomic_sub(total, &t->t_outstanding_credits); read_unlock(&journal->j_state_lock); + jbd2_might_wait_for_commit(journal); write_lock(&journal->j_state_lock); if (jbd2_log_space_left(journal) < jbd2_space_needed(journal)) __jbd2_log_wait_for_space(journal); @@ -255,6 +256,7 @@ static int add_transaction_credits(journ sub_reserved_credits(journal, rsv_blocks); atomic_sub(total, &t->t_outstanding_credits); read_unlock(&journal->j_state_lock); + jbd2_might_wait_for_commit(journal); wait_event(journal->j_wait_reserved, atomic_read(&journal->j_reserved_credits) + rsv_blocks <= journal->j_max_transaction_buffers / 2);