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author | Jan Kara <jack@suse.cz> | 2007-12-04 23:45:27 -0800 |
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committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-12-05 09:21:20 -0800 |
commit | d4beaf4ab5f89496f2bcf67db62ad95d99bfeff6 (patch) | |
tree | ae6d005199017e9a0ade169fd69cb73d6c0ac88f /fs/jbd/commit.c | |
parent | 369b8f5a70402d9fe77006cd0044c8a3fcd08430 (diff) | |
download | op-kernel-dev-d4beaf4ab5f89496f2bcf67db62ad95d99bfeff6.zip op-kernel-dev-d4beaf4ab5f89496f2bcf67db62ad95d99bfeff6.tar.gz |
jbd: Fix assertion failure in fs/jbd/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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/jbd/commit.c')
-rw-r--r-- | fs/jbd/commit.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/fs/jbd/commit.c b/fs/jbd/commit.c index 8f1f2aa..610264b 100644 --- a/fs/jbd/commit.c +++ b/fs/jbd/commit.c @@ -858,10 +858,10 @@ 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 __journal_remove_checkpoint. - * Really, __journal_remove_checkpoint should be using j_state_lock but - * it's a bit hassle to hold that across __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 + * __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); |