From 5c2178e785244341d1e6f2bc3b62f20a337cc44f Mon Sep 17 00:00:00 2001
From: Theodore Ts'o <tytso@mit.edu>
Date: Wed, 27 Oct 2010 21:30:04 -0400
Subject: jbd2: Add sanity check for attempts to start handle during umount
An attempt to modify the file system during the call to
jbd2_destroy_journal() can lead to a system lockup. So add some
checking to make it much more obvious when this happens to and to
determine where the offending code is located.
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
---
fs/jbd2/checkpoint.c | 10 ++++++++++
fs/jbd2/transaction.c | 1 +
2 files changed, 11 insertions(+)
(limited to 'fs/jbd2')
diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 5247e7ffdcb4..524800dce207 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -299,6 +299,16 @@ static int __process_buffer(journal_t *journal, struct journal_head *jh,
transaction->t_chp_stats.cs_forced_to_close++;
spin_unlock(&journal->j_list_lock);
jbd_unlock_bh_state(bh);
+ if (unlikely(journal->j_flags & JBD2_UNMOUNT))
+ /*
+ * The journal thread is dead; so starting and
+ * waiting for a commit to finish will cause
+ * us to wait for a _very_ long time.
+ */
+ printk(KERN_ERR "JBD2: %s: "
+ "Waiting for Godot: block %llu\n",
+ journal->j_devname,
+ (unsigned long long) bh->b_blocknr);
jbd2_log_start_commit(journal, tid);
jbd2_log_wait_commit(journal, tid);
ret = 1;
diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c
index f3479d6e0a83..6bf0a242613e 100644
--- a/fs/jbd2/transaction.c
+++ b/fs/jbd2/transaction.c
@@ -156,6 +156,7 @@ alloc_transaction:
*/
repeat:
read_lock(&journal->j_state_lock);
+ BUG_ON(journal->j_flags & JBD2_UNMOUNT);
if (is_journal_aborted(journal) ||
(journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
read_unlock(&journal->j_state_lock);
--
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