[02/08] Prevent race condition in jbd

From: Greg KH
Date: Tue Apr 05 2005 - 12:08:41 EST



-stable review patch. If anyone has any objections, please let us know.

------------------


This patch from Stephen Tweedie which fixes a race in jbd code (it
demonstrated itself as more or less random NULL dereferences in the
journal code).

Acked-by: Jan Kara <jack@xxxxxxx>
Acked-by: Chris Mason <mason@xxxxxxxx>
Signed-off-by: Chris Wright <chrisw@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

--- linux-2.6-ext3/fs/jbd/transaction.c.=K0000=.orig
+++ linux-2.6-ext3/fs/jbd/transaction.c
@@ -1775,10 +1775,10 @@ static int journal_unmap_buffer(journal_
JBUFFER_TRACE(jh, "checkpointed: add to BJ_Forget");
ret = __dispose_buffer(jh,
journal->j_running_transaction);
+ journal_put_journal_head(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&journal->j_state_lock);
- journal_put_journal_head(jh);
return ret;
} else {
/* There is no currently-running transaction. So the
@@ -1789,10 +1789,10 @@ static int journal_unmap_buffer(journal_
JBUFFER_TRACE(jh, "give to committing trans");
ret = __dispose_buffer(jh,
journal->j_committing_transaction);
+ journal_put_journal_head(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&journal->j_state_lock);
- journal_put_journal_head(jh);
return ret;
} else {
/* The orphan record's transaction has
@@ -1813,10 +1813,10 @@ static int journal_unmap_buffer(journal_
journal->j_running_transaction);
jh->b_next_transaction = NULL;
}
+ journal_put_journal_head(jh);
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
spin_unlock(&journal->j_state_lock);
- journal_put_journal_head(jh);
return 0;
} else {
/* Good, the buffer belongs to the running transaction.

-
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