[PATCH 3.14 74/79] jbd2: avoid infinite loop when destroying aborted journal

From: Greg Kroah-Hartman
Date: Sat Oct 17 2015 - 23:11:47 EST

3.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Jan Kara <jack@xxxxxxxx>

commit 841df7df196237ea63233f0f9eaa41db53afd70f upstream.

Commit 6f6a6fda2945 "jbd2: fix ocfs2 corrupt when updating journal
superblock fails" changed jbd2_cleanup_journal_tail() to return EIO
when the journal is aborted. That makes logic in
jbd2_log_do_checkpoint() bail out which is fine, except that
jbd2_journal_destroy() expects jbd2_log_do_checkpoint() to always make
a progress in cleaning the journal. Without it jbd2_journal_destroy()
just loops in an infinite loop.

Fix jbd2_journal_destroy() to cleanup journal checkpoint lists of
jbd2_log_do_checkpoint() fails with error.

Reported-by: Eryu Guan <guaneryu@xxxxxxxxx>
Tested-by: Eryu Guan <guaneryu@xxxxxxxxx>
Fixes: 6f6a6fda294506dfe0e3e0a253bb2d2923f28f0a
Signed-off-by: Jan Kara <jack@xxxxxxxx>
Signed-off-by: Theodore Ts'o <tytso@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
fs/jbd2/checkpoint.c | 39 +++++++++++++++++++++++++++++++++------
fs/jbd2/commit.c | 2 +-
fs/jbd2/journal.c | 11 ++++++++++-
include/linux/jbd2.h | 3 ++-
4 files changed, 46 insertions(+), 9 deletions(-)

--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -475,14 +475,15 @@ int jbd2_cleanup_journal_tail(journal_t
* journal_clean_one_cp_list
*
* Find all the written-back checkpoint buffers in the given list and
- * release them.
+ * release them. If 'destroy' is set, clean all buffers unconditionally.
*
* Called with the journal locked.
* Called with j_list_lock held.
* Returns number of buffers reaped (for debug)
*/

-static int journal_clean_one_cp_list(struct journal_head *jh, int *released)
+static int journal_clean_one_cp_list(struct journal_head *jh, bool destroy,
+ int *released)
{
struct journal_head *last_jh;
struct journal_head *next_jh = jh;
@@ -496,7 +497,10 @@ static int journal_clean_one_cp_list(str
do {
jh = next_jh;
next_jh = jh->b_cpnext;
- ret = __try_to_free_cp_buf(jh);
+ if (!destroy)
+ ret = __try_to_free_cp_buf(jh);
+ else
+ ret = __jbd2_journal_remove_checkpoint(jh) + 1;
if (ret) {
freed++;
if (ret == 2) {
@@ -521,13 +525,14 @@ static int journal_clean_one_cp_list(str
* journal_clean_checkpoint_list
*
* Find all the written-back checkpoint buffers in the journal and release them.
+ * If 'destroy' is set, release all buffers unconditionally.
*
* Called with the journal locked.
* Called with j_list_lock held.
* Returns number of buffers reaped (for debug)
*/

-int __jbd2_journal_clean_checkpoint_list(journal_t *journal)
+int __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy)
{
transaction_t *transaction, *last_transaction, *next_transaction;
int ret = 0;
@@ -543,7 +548,7 @@ int __jbd2_journal_clean_checkpoint_list
transaction = next_transaction;
next_transaction = transaction->t_cpnext;
ret += journal_clean_one_cp_list(transaction->
- t_checkpoint_list, &released);
+ t_checkpoint_list, destroy, &released);
/*
* This function only frees up some memory if possible so we
* dont have an obligation to finish processing. Bail out if
@@ -559,7 +564,7 @@ int __jbd2_journal_clean_checkpoint_list
* we can possibly see not yet submitted buffers on io_list
*/
ret += journal_clean_one_cp_list(transaction->
- t_checkpoint_io_list, &released);
+ t_checkpoint_io_list, destroy, &released);
if (need_resched())
goto out;
} while (transaction != last_transaction);
@@ -568,6 +573,28 @@ out:
}

/*
+ * Remove buffers from all checkpoint lists as journal is aborted and we just
+ * need to free memory
+ */
+void jbd2_journal_destroy_checkpoint(journal_t *journal)
+{
+ /*
+ * We loop because __jbd2_journal_clean_checkpoint_list() may abort
+ * early due to a need of rescheduling.
+ */
+ while (1) {
+ spin_lock(&journal->j_list_lock);
+ if (!journal->j_checkpoint_transactions) {
+ spin_unlock(&journal->j_list_lock);
+ break;
+ }
+ __jbd2_journal_clean_checkpoint_list(journal, true);
+ spin_unlock(&journal->j_list_lock);
+ cond_resched();
+ }
+}
+
+/*
* journal_remove_checkpoint: called after a buffer has been committed
* to disk (either by being write-back flushed to disk, or being
* committed to the log).
--- a/fs/jbd2/commit.c
+++ b/fs/jbd2/commit.c
@@ -510,7 +510,7 @@ void jbd2_journal_commit_transaction(jou
* frees some memory
*/
spin_lock(&journal->j_list_lock);
- __jbd2_journal_clean_checkpoint_list(journal);
+ __jbd2_journal_clean_checkpoint_list(journal, false);
spin_unlock(&journal->j_list_lock);

jbd_debug(3, "JBD2: commit phase 1\n");
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -1708,8 +1708,17 @@ int jbd2_journal_destroy(journal_t *jour
while (journal->j_checkpoint_transactions != NULL) {
spin_unlock(&journal->j_list_lock);
mutex_lock(&journal->j_checkpoint_mutex);
- jbd2_log_do_checkpoint(journal);
+ err = jbd2_log_do_checkpoint(journal);
mutex_unlock(&journal->j_checkpoint_mutex);
+ /*
+ * If checkpointing failed, just free the buffers to avoid
+ * looping forever
+ */
+ if (err) {
+ jbd2_journal_destroy_checkpoint(journal);
+ spin_lock(&journal->j_list_lock);
+ break;
+ }
spin_lock(&journal->j_list_lock);
}

--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -1042,8 +1042,9 @@ void jbd2_update_log_tail(journal_t *jou
extern void jbd2_journal_commit_transaction(journal_t *);

/* Checkpoint list management */
-int __jbd2_journal_clean_checkpoint_list(journal_t *journal);
+int __jbd2_journal_clean_checkpoint_list(journal_t *journal, bool destroy);
int __jbd2_journal_remove_checkpoint(struct journal_head *);
+void jbd2_journal_destroy_checkpoint(journal_t *journal);
void __jbd2_journal_insert_checkpoint(struct journal_head *, transaction_t *);




--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/