Commit 24dc9864 authored Jun 17, 2020 by Lukas Czerner Committed by Theodore Ts'o Aug 06, 2020

jbd2: make sure jh have b_transaction set in refile/unfile_buffer



Callers of __jbd2_journal_unfile_buffer() and
__jbd2_journal_refile_buffer() assume that the b_transaction is set. In
fact if it's not, we can end up with journal_head refcounting errors
leading to crash much later that might be very hard to track down. Add
asserts to make sure that is the case.

We also make sure that b_next_transaction is NULL in
__jbd2_journal_unfile_buffer() since the callers expect that as well and
we should not get into that stage in this state anyway, leading to
problems later on if we do.

Tested with fstests.

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200617092549.6712-1-lczerner@redhat.com


Signed-off-by: Theodore Ts'o <tytso@mit.edu>

parent e030a288

fs/jbd2/transaction.c

+10 −0

Original line number	Diff line number	Diff line
		@@ -2026,6 +2026,9 @@ static void __jbd2_journal_temp_unlink_buffer(struct journal_head *jh)
		*/
		static void __jbd2_journal_unfile_buffer(struct journal_head *jh)
		{
		J_ASSERT_JH(jh, jh->b_transaction != NULL);
		J_ASSERT_JH(jh, jh->b_next_transaction == NULL);

		__jbd2_journal_temp_unlink_buffer(jh);
		jh->b_transaction = NULL;
		}
		@@ -2572,6 +2575,13 @@ bool __jbd2_journal_refile_buffer(struct journal_head *jh)

		was_dirty = test_clear_buffer_jbddirty(bh);
		__jbd2_journal_temp_unlink_buffer(jh);

		/*
		* b_transaction must be set, otherwise the new b_transaction won't
		* be holding jh reference
		*/
		J_ASSERT_JH(jh, jh->b_transaction != NULL);

		/*
		* We set b_transaction here because b_next_transaction will inherit
		* our jh reference and thus __jbd2_journal_file_buffer() must not

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