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[FOR-STABLE,09/20] jbd2: abort instead of waiting for nonexistent transaction

Message ID 1226851540-8032-10-git-send-email-tytso@mit.edu
State Not Applicable, archived
Headers show

Commit Message

Theodore Ts'o Nov. 16, 2008, 4:05 p.m. UTC
From: Duane Griffin <duaneg@dghda.com>

The __jbd2_log_wait_for_space function sits in a loop checkpointing
transactions until there is sufficient space free in the journal.
However, if there are no transactions to be processed (e.g.  because the
free space calculation is wrong due to a corrupted filesystem) it will
never progress.

Check for space being required when no transactions are outstanding and
abort the journal instead of endlessly looping.

This patch fixes the bug reported by Sami Liedes at:
http://bugzilla.kernel.org/show_bug.cgi?id=10976

Signed-off-by: Duane Griffin <duaneg@dghda.com>
Cc: Sami Liedes <sliedes@cc.hut.fi>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
(cherry picked from commit 23f8b79eae8a74e42a006ffa7c456e295c7e1c0d)
---
 fs/jbd2/checkpoint.c |   19 +++++++++++++++++--
 1 files changed, 17 insertions(+), 2 deletions(-)
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Patch

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 91389c8..af4651b 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -126,14 +126,29 @@  void __jbd2_log_wait_for_space(journal_t *journal)
 
 		/*
 		 * Test again, another process may have checkpointed while we
-		 * were waiting for the checkpoint lock
+		 * were waiting for the checkpoint lock. If there are no
+		 * outstanding transactions there is nothing to checkpoint and
+		 * we can't make progress. Abort the journal in this case.
 		 */
 		spin_lock(&journal->j_state_lock);
+		spin_lock(&journal->j_list_lock);
 		nblocks = jbd_space_needed(journal);
 		if (__jbd2_log_space_left(journal) < nblocks) {
+			int chkpt = journal->j_checkpoint_transactions != NULL;
+
+			spin_unlock(&journal->j_list_lock);
 			spin_unlock(&journal->j_state_lock);
-			jbd2_log_do_checkpoint(journal);
+			if (chkpt) {
+				jbd2_log_do_checkpoint(journal);
+			} else {
+				printk(KERN_ERR "%s: no transactions\n",
+				       __func__);
+				jbd2_journal_abort(journal, 0);
+			}
+
 			spin_lock(&journal->j_state_lock);
+		} else {
+			spin_unlock(&journal->j_list_lock);
 		}
 		mutex_unlock(&journal->j_checkpoint_mutex);
 	}