linux-ext4 - [PATCH] jbd: don't give up looking for space so easily in __log_wait_for

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed,  5 Nov 2008 09:05:07 -0500
From:	Theodore Ts'o <tytso@....edu>
To:	Ext4 Developers List <linux-ext4@...r.kernel.org>
Cc:	Theodore Ts'o <tytso@....edu>, Duane Griffin <duaneg@...da.com>,
	Toshiyuki Okajima <toshi.okajima@...fujitsu.com>
Subject: [PATCH] jbd: don't give up looking for space so easily in __log_wait_for_space

Commit be07c4ed introducd a regression because it assumed that if
there were no transactions ready to be checkpointed, that no progress
could be made on making space available in the journal, and so the
journal should be aborted.  This assumption is false; it could be the
case that simply calling cleanup_journal_tail() will recover the
necessary space, or, for small journals, the currently committing
transaction could be responsible for chewing up the required space in
the log, so we need to wait for the currently committing transaction
to finish before trying to force a checkpoint operation.

This patch fixes the bug reported by Meelis Roos at:
http://bugzilla.kernel.org/show_bug.cgi?id=11937

Signed-off-by: "Theodore Ts'o" <tytso@....edu>
Cc: Duane Griffin <duaneg@...da.com>
Cc: Toshiyuki Okajima <toshi.okajima@...fujitsu.com>
---
 fs/jbd/checkpoint.c |   27 ++++++++++++++++++++++-----
 1 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/fs/jbd/checkpoint.c b/fs/jbd/checkpoint.c
index 1bd8d4a..5e856de 100644
--- a/fs/jbd/checkpoint.c
+++ b/fs/jbd/checkpoint.c
@@ -128,25 +128,42 @@ void __log_wait_for_space(journal_t *journal)
 		/*
 		 * Test again, another process may have checkpointed while we
 		 * 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.
+		 * transactions ready to be checkpointed, try to recover
+		 * journal space by calling cleanup_journal_tail(), and if
+		 * that doesn't work, by waiting for the currently committing
+		 * transaction to complete.  If there is absolutely no way
+		 * to make progress, this is either a BUG or corrupted
+		 * filesystem, so abort the journal and leave a stack
+		 * trace for forensic evidence.
 		 */
 		spin_lock(&journal->j_state_lock);
 		spin_lock(&journal->j_list_lock);
 		nblocks = jbd_space_needed(journal);
 		if (__log_space_left(journal) < nblocks) {
 			int chkpt = journal->j_checkpoint_transactions != NULL;
+			int tid = 0;
 
+			if (journal->j_committing_transaction)
+				tid = journal->j_committing_transaction->t_tid;
 			spin_unlock(&journal->j_list_lock);
 			spin_unlock(&journal->j_state_lock);
 			if (chkpt) {
 				log_do_checkpoint(journal);
+			} else if (cleanup_journal_tail(journal) == 0) {
+				/* We were able to recover space; yay! */
+				;
+			} else if (tid) {
+				log_wait_commit(journal, tid);
 			} else {
-				printk(KERN_ERR "%s: no transactions\n",
-				       __func__);
+				printk(KERN_ERR "%s: needed %d blocks and "
+				       "only had %d space available\n",
+				       __func__, nblocks,
+				       __log_space_left(journal));
+				printk(KERN_ERR "%s: no way to get more "
+				       "journal space\n", __func__);
+				WARN_ON(1);
 				journal_abort(journal, 0);
 			}
-
 			spin_lock(&journal->j_state_lock);
 		} else {
 			spin_unlock(&journal->j_list_lock);
-- 
1.5.6.1.205.ge2c7.dirty

--
To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html