Re: [Ext2-devel] OOM problems still left in 2.6.13-rc3

From: Andreas Dilger
Date: Fri Jul 29 2005 - 12:11:50 EST


On Jul 29, 2005 21:36 +0900, Takashi Sato wrote:
> The buffers connected to t_sync_datalist can't simply be removed like
> the buffers connected to t_locked_list, since we don't know if the
> I/O against the buffers are complete.
>
> So we should wait until the committing transaction becomes complete
> if there are any buffers connected to the transaction's
> t_sync_datalist.
>
> b) If journal_unmap_buffer() returns -1 on journal_invalidatepages(),
> call log_wait_commit() to wait for the completion of the
> transaction, and retry to call journal_unmap_buffer() again.
>
> @@ -1899,8 +1896,19 @@ int journal_invalidatepage(journal_t *jo
>
> if (offset <= curr_off) {
> /* This block is wholly outside the truncation point */
> +retry:
> lock_buffer(bh);
> - may_free &= journal_unmap_buffer(journal, bh);
> + ret = journal_unmap_buffer(journal, bh, &wait_tid);
> + /* When this buffer is in transaction of
> + * t_sync_datalist, truncate must wait for
> + * that transaction.
> + */
> + if (ret < 0) {
> + unlock_buffer(bh);
> + log_wait_commit(journal, wait_tid);
> + goto retry;
> + }
> + may_free &= ret;

What kind of effect does this have on filesystem performance?
This would apparently make truncate be synchronous with journal commit due to
truncate_{partial,complete}_page->do_invalidatepage->journal_invalidatepage().

Cheers, Andreas
--
Andreas Dilger
Principal Software Engineer
Cluster File Systems, Inc.

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