From: "Patrick J. LoPresti" Subject: [PATCH 2/3] JBD2: Allow feature checks before journal recovery Date: Thu, 22 Jul 2010 15:04:16 -0700 Message-ID: <8739vb2mxr.fsf@patl.com> References: <874ofr2myq.fsf@patl.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: ocfs2-devel@oss.oracle.com Return-path: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: ocfs2-devel-bounces@oss.oracle.com Errors-To: ocfs2-devel-bounces@oss.oracle.com List-Id: linux-ext4.vger.kernel.org Before we start accessing a huge (> 16 TiB) OCFS2 volume, we need to confirm that its journal supports 64-bit offsets. In particular, we need to check the journal's feature bits before recovering the journal. This is not possible with JBD2 at present, because the journal superblock (where the feature bits reside) is not loaded from disk until the journal is recovered. This patch loads the journal superblock in jbd2_journal_check_used_features() if it has not already been loaded, allowing us to check the feature bits before journal recovery. Signed-off-by: Patrick LoPresti diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index bc2ff59..5cfd8d4 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1365,6 +1365,10 @@ int jbd2_journal_check_used_features (journal_t *journal, unsigned long compat, if (!compat && !ro && !incompat) return 1; + /* Load journal superblock if it is not loaded yet. */ + if (journal->j_format_version == 0 && + journal_get_superblock(journal) != 0) + return 0; if (journal->j_format_version == 1) return 0;