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| author | Jan Kara <jack@suse.cz> | 2008-01-29 07:58:27 +0300 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2008-01-29 07:58:27 +0300 |
| commit | f5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0 (patch) | |
| tree | cbb2bc79a488461bf3bec9b60d15e21717dc8360 /fs/jbd2/commit.c | |
| parent | 36df53f4a3e445175fc1e9d7f433599482ec6d7f (diff) | |
| download | linux-f5a7a6b0d9b6af7d46124ed3f6b3995225cb62d0.tar.xz | |
jbd2: Fix assertion failure in fs/jbd2/checkpoint.c
Before we start committing a transaction, we call
__journal_clean_checkpoint_list() to cleanup transaction's written-back
buffers.
If this call happens to remove all of them (and there were already some
buffers), __journal_remove_checkpoint() will decide to free the transaction
because it isn't (yet) a committing transaction and soon we fail some
assertion - the transaction really isn't ready to be freed :).
We change the check in __journal_remove_checkpoint() to free only a
transaction in T_FINISHED state. The locking there is subtle though (as
everywhere in JBD ;(). We use j_list_lock to protect the check and a
subsequent call to __journal_drop_transaction() and do the same in the end
of journal_commit_transaction() which is the only place where a transaction
can get to T_FINISHED state.
Probably I'm too paranoid here and such locking is not really necessary -
checkpoint lists are processed only from log_do_checkpoint() where a
transaction must be already committed to be processed or from
__journal_clean_checkpoint_list() where kjournald itself calls it and thus
transaction cannot change state either. Better be safe if something
changes in future...
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'fs/jbd2/commit.c')
| -rw-r--r-- | fs/jbd2/commit.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/jbd2/commit.c b/fs/jbd2/commit.c index 6986f334c643..39b5cee3dd8a 100644 --- a/fs/jbd2/commit.c +++ b/fs/jbd2/commit.c @@ -867,10 +867,10 @@ restart_loop: } spin_unlock(&journal->j_list_lock); /* - * This is a bit sleazy. We borrow j_list_lock to protect - * journal->j_committing_transaction in __jbd2_journal_remove_checkpoint. - * Really, __jbd2_journal_remove_checkpoint should be using j_state_lock but - * it's a bit hassle to hold that across __jbd2_journal_remove_checkpoint + * This is a bit sleazy. We use j_list_lock to protect transition + * of a transaction into T_FINISHED state and calling + * __jbd2_journal_drop_transaction(). Otherwise we could race with + * other checkpointing code processing the transaction... */ spin_lock(&journal->j_state_lock); spin_lock(&journal->j_list_lock); |