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Commit dc6e8d66 authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

jbd2: don't call get_bh() before calling __jbd2_journal_remove_checkpoint() 



The __jbd2_journal_remove_checkpoint() doesn't require an elevated
b_count; indeed, until the jh structure gets released by the call to
jbd2_journal_put_journal_head(), the bh's b_count is elevated by
virtue of the existence of the jh structure.

Suggested-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 754cfed6

fs/jbd2/checkpoint.c

+5 −14
Original line number Diff line number Diff line
@@ -96,15 +96,8 @@ static int __try_to_free_cp_buf(struct journal_head *jh) 


	if (jh->b_transaction == NULL && !buffer_locked(bh) &&

	    !buffer_dirty(bh) && !buffer_write_io_error(bh)) {

		/*

		 * Get our reference so that bh cannot be freed before

		 * we unlock it

		 */

		get_bh(bh);

		JBUFFER_TRACE(jh, "remove from checkpoint list");

		ret = __jbd2_journal_remove_checkpoint(jh) + 1;

		BUFFER_TRACE(bh, "release");

		__brelse(bh);

	}

	return ret;

}
@@ -216,7 +209,7 @@ int jbd2_log_do_checkpoint(journal_t *journal) 
	struct buffer_head	*bh;

	transaction_t		*transaction;

	tid_t			this_tid;

	int			result, batch_count = 0, done = 0;

	int			result, batch_count = 0;



	jbd_debug(1, "Start checkpoint\n");
@@ -291,11 +284,9 @@ int jbd2_log_do_checkpoint(journal_t *journal) 
		if (!buffer_dirty(bh)) {

			if (unlikely(buffer_write_io_error(bh)) && !result)

				result = -EIO;

			get_bh(bh);

			BUFFER_TRACE(bh, "remove from checkpoint");

			__jbd2_journal_remove_checkpoint(jh);

			spin_unlock(&journal->j_list_lock);

			__brelse(bh);

			goto retry;

		}

		/*
@@ -338,12 +329,12 @@ int jbd2_log_do_checkpoint(journal_t *journal) 
	    transaction->t_tid != this_tid)

		goto out;



	while (!done && transaction->t_checkpoint_io_list) {

	while (transaction->t_checkpoint_io_list) {

		jh = transaction->t_checkpoint_io_list;

		bh = jh2bh(jh);

		get_bh(bh);

		if (buffer_locked(bh)) {

			spin_unlock(&journal->j_list_lock);

			get_bh(bh);

			wait_on_buffer(bh);

			/* the journal_head may have gone by now */

			BUFFER_TRACE(bh, "brelse");
@@ -359,8 +350,8 @@ int jbd2_log_do_checkpoint(journal_t *journal) 
		 * know that it has been written out and so we can

		 * drop it from the list

		 */

		done = __jbd2_journal_remove_checkpoint(jh);

		__brelse(bh);

		if (__jbd2_journal_remove_checkpoint(jh))

			break;

	}

out:

	spin_unlock(&journal->j_list_lock);