Messages in this thread Patch in this message | | | Date | Thu, 12 Oct 2006 15:07:11 -0500 | From | Eric Sandeen <> | Subject | Re: 2.6.18 ext3 panic. |
| |
Andrew Morton wrote:
> On Thu, 12 Oct 2006 14:28:20 +0200 > Jan Kara <jack@suse.cz> wrote: > > >> Where can we call >> journal_dirty_data() without PageLock? >> > > block_write_full_page() will unlock the page, so ext3_writepage() > will run journal_dirty_data_fn() against an unlocked page. > > I haven't looked into the exact details of the race, but it should > be addressable via jbd_lock_bh_state() or j_list_lock coverage I'm testing with something like this now; seem sane?
journal_dirty_data & journal_unmap_data both check do jbd_lock_bh_state(bh) close to the top... journal_dirty_data_fn has checked buffer_mapped before getting into journal_dirty_data, but that state may change before the lock is grabbed. Similarly re-check after we drop the lock.
-Eric
Index: linux-2.6.18-1.2737.fc6/fs/jbd/transaction.c =================================================================== --- linux-2.6.18-1.2737.fc6.orig/fs/jbd/transaction.c +++ linux-2.6.18-1.2737.fc6/fs/jbd/transaction.c @@ -967,6 +967,13 @@ int journal_dirty_data(handle_t *handle, */ jbd_lock_bh_state(bh); spin_lock(&journal->j_list_lock); + + /* Now that we have bh_state locked, are we really still mapped? */ + if (!buffer_mapped(bh)) { + JBUFFER_TRACE(jh, "unmapped, bailing out"); + goto no_journal; + } + if (jh->b_transaction) { JBUFFER_TRACE(jh, "has transaction"); if (jh->b_transaction != handle->h_transaction) { @@ -1028,6 +1036,11 @@ int journal_dirty_data(handle_t *handle, sync_dirty_buffer(bh); jbd_lock_bh_state(bh); spin_lock(&journal->j_list_lock); + /* Since we dropped the lock... */ + if (!buffer_mapped(bh)) { + JBUFFER_TRACE(jh, "Got unmapped"); + goto no_journal; + } /* The buffer may become locked again at any time if it is redirtied */ } - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |