Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932290AbcDZXei (ORCPT ); Tue, 26 Apr 2016 19:34:38 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:41247 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755014AbcDZXef (ORCPT ); Tue, 26 Apr 2016 19:34:35 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "OGAWA Hirofumi" , "Theodore Ts'o" Date: Wed, 27 Apr 2016 01:02:24 +0200 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 027/115] jbd2: fix FS corruption possibility in jbd2_journal_destroy() on umount path In-Reply-To: X-SA-Exim-Connect-IP: 2a02:8426:ae4:c500:9cba:69ae:962d:6167 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4102 Lines: 122 3.2.80-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: OGAWA Hirofumi commit c0a2ad9b50dd80eeccd73d9ff962234590d5ec93 upstream. On umount path, jbd2_journal_destroy() writes latest transaction ID (->j_tail_sequence) to be used at next mount. The bug is that ->j_tail_sequence is not holding latest transaction ID in some cases. So, at next mount, there is chance to conflict with remaining (not overwritten yet) transactions. mount (id=10) write transaction (id=11) write transaction (id=12) umount (id=10) <= the bug doesn't write latest ID mount (id=10) write transaction (id=11) crash mount [recovery process] transaction (id=11) transaction (id=12) <= valid transaction ID, but old commit must not replay Like above, this bug become the cause of recovery failure, or FS corruption. So why ->j_tail_sequence doesn't point latest ID? Because if checkpoint transactions was reclaimed by memory pressure (i.e. bdev_try_to_free_page()), then ->j_tail_sequence is not updated. (And another case is, __jbd2_journal_clean_checkpoint_list() is called with empty transaction.) So in above cases, ->j_tail_sequence is not pointing latest transaction ID at umount path. Plus, REQ_FLUSH for checkpoint is not done too. So, to fix this problem with minimum changes, this patch updates ->j_tail_sequence, and issue REQ_FLUSH. (With more complex changes, some optimizations would be possible to avoid unnecessary REQ_FLUSH for example though.) BTW, journal->j_tail_sequence = ++journal->j_transaction_sequence; Increment of ->j_transaction_sequence seems to be unnecessary, but ext3 does this. Signed-off-by: OGAWA Hirofumi Signed-off-by: Theodore Ts'o Signed-off-by: Ben Hutchings --- fs/jbd2/journal.c | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -1340,11 +1340,12 @@ out: /** * jbd2_mark_journal_empty() - Mark on disk journal as empty. * @journal: The journal to update. + * @write_op: With which operation should we write the journal sb * * Update a journal's dynamic superblock fields to show that journal is empty. * Write updated superblock to disk waiting for IO to complete. */ -static void jbd2_mark_journal_empty(journal_t *journal) +static void jbd2_mark_journal_empty(journal_t *journal, int write_op) { journal_superblock_t *sb = journal->j_superblock; @@ -1357,7 +1358,7 @@ static void jbd2_mark_journal_empty(jour sb->s_start = cpu_to_be32(0); read_unlock(&journal->j_state_lock); - jbd2_write_superblock(journal, WRITE_FUA); + jbd2_write_superblock(journal, write_op); /* Log is no longer empty */ write_lock(&journal->j_state_lock); @@ -1593,7 +1594,13 @@ int jbd2_journal_destroy(journal_t *jour if (journal->j_sb_buffer) { if (!is_journal_aborted(journal)) { mutex_lock(&journal->j_checkpoint_mutex); - jbd2_mark_journal_empty(journal); + + write_lock(&journal->j_state_lock); + journal->j_tail_sequence = + ++journal->j_transaction_sequence; + write_unlock(&journal->j_state_lock); + + jbd2_mark_journal_empty(journal, WRITE_FLUSH_FUA); mutex_unlock(&journal->j_checkpoint_mutex); } else err = -EIO; @@ -1859,7 +1866,7 @@ int jbd2_journal_flush(journal_t *journa * the magic code for a fully-recovered superblock. Any future * commits of data to the journal will restore the current * s_start value. */ - jbd2_mark_journal_empty(journal); + jbd2_mark_journal_empty(journal, WRITE_FUA); mutex_unlock(&journal->j_checkpoint_mutex); write_lock(&journal->j_state_lock); J_ASSERT(!journal->j_running_transaction); @@ -1905,7 +1912,7 @@ int jbd2_journal_wipe(journal_t *journal if (write) { /* Lock to make assertions happy... */ mutex_lock(&journal->j_checkpoint_mutex); - jbd2_mark_journal_empty(journal); + jbd2_mark_journal_empty(journal, WRITE_FUA); mutex_unlock(&journal->j_checkpoint_mutex); }