On Wed, 2008-05-14 at 20:14 +0200, Jan Kara wrote: > On Wed 14-05-08 10:41:12, Mingming Cao wrote: > > > > Bummer, we can't free buffers in ext3_launder_page() before calling > > > > try_to_free_page, as later > > > > invalidate_complete_page2()->try_to_free_page() expecting the page > > > > buffers are still here, and will return EIO if it launder_page() has > > > > already freed those buffers.:( > > > Are you sure? Because if bufferes are released in ext3_launder_page(), > > > PagePrivate() has been set to 0 and we should directly fall through to > > > releasing the page without ever calling try_to_release_page()... So I'd > > > want to find out why PagePrivate is still set in > > > invalidate_complete_page2(). > > > > > > > You are right. PagePrivate() is being set to 0 in drop_buffers(). > > > > The problem is do_launder_page() returns successfully if the page is not > > dirty (our case), so ext3_launder_page() is not even get called. This > > also explains why the log_wait_commit() approach doesn't work for me:( > I didn't realize PageDirty() is going to be already cleared by previous > writes... :( > > > Have to think other ways...could we pass some flag to > > journal_try_to_free_buffers(), and ask journal_try_to_free_buffers() > > wait for jbd commit to finish flushing the data, if the request is from > > directo IO? > Well, we could do that but we'd have to change try_to_release_page() call > to accept an extra argument which would consequently mean changing all the > filesystems... Actually there is an argument gfp_mask passed to try_to_release_page() which we could pass a special flag from direct IO that could be parsed as direct IO request. This would avoid changing all the filesystems and the address space operation interface. In fact, I don't see in-kernel tree fs releasepage() cal back functions is using this gfp_mask, but btrfs is using it. > But yes, it probably makes sence because it is really > different whether we should just release the page because of memory > pressure or because direct IO needs to write to that area of the file. > So adding the parameter to releasepage() callback is probably a reasonable > thing to do. > Will send a patch shortly, with that patch the test fine for about 18 hours. -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
