>I modified my patch.
>I do not change Checking b_count in a loop, but introduce
>set_current_state(TASK_UNINTERRUPTIBLE) to mitigate the loop. I think this can
>lead to avoid busy loop.
>I used the same approach of do_sync_read()->wait_on_retry_sync_kiocb or
>some drivers(qla2xxx).
>
>Signed-off-by: Hisashi Hifumi <hifumi.hisashi@xxxxxxxxxxxxx>
>
>diff -Nrup linux-2.6.27-rc1.org/fs/jbd/transaction.c
>linux-2.6.27-rc1.jbdfix/fs/jbd/transaction.c
>--- linux-2.6.27-rc1.org/fs/jbd/transaction.c 2008-07-29 19:28:47.000000000 +0900
>+++ linux-2.6.27-rc1.jbdfix/fs/jbd/transaction.c 2008-08-06
>13:35:37.000000000 +0900
>@@ -1764,6 +1764,15 @@ int journal_try_to_free_buffers(journal_
> */
> if (ret == 0 && (gfp_mask & __GFP_WAIT) && (gfp_mask & __GFP_FS)) {
> journal_wait_for_transaction_sync_data(journal);
>+
>+ bh = head;
>+ do {
>+ while (atomic_read(&bh->b_count)) {
>+ set_current_state(TASK_UNINTERRUPTIBLE);
>+ schedule();
>+ __set_current_state(TASK_RUNNING);
>+ }
>+ } while ((bh = bh->b_this_page) != head);
> ret = try_to_free_buffers(page);
> }
Sorry, the thread entering this loop sleeps infinitely.
We should add some wait queue and implement wait/wakeup code.
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