From: Theodore Ts'o Subject: [PATCH 2/2] jbd2: return ENOSPC in journal_dirty_metadata if a handle runs out of space Date: Mon, 2 Dec 2013 09:45:02 -0500 Message-ID: <1385995502-8344-2-git-send-email-tytso@mit.edu> References: <1385995502-8344-1-git-send-email-tytso@mit.edu> Cc: Theodore Ts'o , ocfs2-devel@oss.oracle.com To: Ext4 Developers List Return-path: Received: from imap.thunk.org ([74.207.234.97]:35621 "EHLO imap.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751438Ab3LBOpK (ORCPT ); Mon, 2 Dec 2013 09:45:10 -0500 In-Reply-To: <1385995502-8344-1-git-send-email-tytso@mit.edu> Sender: linux-ext4-owner@vger.kernel.org List-ID: If a handle runs out of space, we currently stop the kernel with a BUG. This makes it hard to figure out what might be going on. So return an error of ENOSPC, so we can let the file system layer figure out what is going on, to make it more likely we can get useful debugging information). This should make it easier to debug problems such as the one which was reported by: https://bugzilla.kernel.org/show_bug.cgi?id=44731 The only two callers of this function are ext4_handle_dirty_metadata() and ocfs2_journal_dirty(). The ocfs2 function will trigger a BUG_ON(), which means there will be no change in behavior. The ext4 function will call ext4_error_inode() which will print the useful debugging information and then handle the situation using ext4's error handling mechanisms (i.e., which might mean halting the kernel or remounting the file system read-only). Also, since both file systems already call WARN_ON(), drop the WARN_ON from jbd2_journal_dirty_metadata() to avoid two stack traces from being displayed. Signed-off-by: "Theodore Ts'o" Cc: ocfs2-devel@oss.oracle.com --- fs/jbd2/transaction.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index 7aa9a32..b0b74e5 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -1290,7 +1290,10 @@ int jbd2_journal_dirty_metadata(handle_t *handle, struct buffer_head *bh) * once a transaction -bzzz */ jh->b_modified = 1; - J_ASSERT_JH(jh, handle->h_buffer_credits > 0); + if (handle->h_buffer_credits <= 0) { + ret = -ENOSPC; + goto out_unlock_bh; + } handle->h_buffer_credits--; } @@ -1373,7 +1376,6 @@ out_unlock_bh: jbd2_journal_put_journal_head(jh); out: JBUFFER_TRACE(jh, "exit"); - WARN_ON(ret); /* All errors are bugs, so dump the stack */ return ret; } -- 1.8.5.rc3.362.gdf10213