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Commit e03a9976 authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o
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jbd2: fix lockdep annotation in add_transaction_credits() 



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.

Cc: stable@vger.kernel.org
Fixes: 1eaa566d
Reported-by: default avatarThomas Gleixner <tglx@linutronix.de>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 7c5f6b32

fs/jbd2/transaction.c

+4 −2
Original line number Diff line number Diff line
@@ -159,6 +159,7 @@ static void wait_transaction_locked(journal_t *journal) 
	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(journal_t *journal, int blocks, 
	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(journal_t *journal, int blocks, 
		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(journal_t *journal, int blocks, 
	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(journal_t *journal, int blocks, 
		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);