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authorJan Kara <jack@suse.cz>2017-04-30 03:12:16 +0300
committerTheodore Ts'o <tytso@mit.edu>2017-04-30 03:12:16 +0300
commitc52c47e4b4fbe4284602fc2ccbfc4a4d8dc05b49 (patch)
tree4b61b1a2c7c8ff64679d49c191149fcadfb78176
parent80a2ea9f85850f1cdae814be03b4a16c3d3abc00 (diff)
downloadlinux-c52c47e4b4fbe4284602fc2ccbfc4a4d8dc05b49.tar.xz
jbd2: Fix lockdep splat with generic/270 test
I've hit a lockdep splat with generic/270 test complaining that: 3216.fsstress.b/3533 is trying to acquire lock: (jbd2_handle){++++..}, at: [<ffffffff813152e0>] jbd2_log_wait_commit+0x0/0x150 but task is already holding lock: (jbd2_handle){++++..}, at: [<ffffffff8130bd3b>] start_this_handle+0x35b/0x850 The underlying problem is that jbd2_journal_force_commit_nested() (called from ext4_should_retry_alloc()) may get called while a transaction handle is started. In such case it takes care to not wait for commit of the running transaction (which would deadlock) but only for a commit of a transaction that is already committing (which is safe as that doesn't wait for any filesystem locks). In fact there are also other callers of jbd2_log_wait_commit() that take care to pass tid of a transaction that is already committing and for those cases, the lockdep instrumentation is too restrictive and leading to false positive reports. Fix the problem by calling jbd2_might_wait_for_commit() from jbd2_log_wait_commit() only if the transaction isn't already committing. Fixes: 1eaa566d368b214d99cbb973647c1b0b8102a9ae Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
-rw-r--r--fs/jbd2/journal.c15
1 files changed, 14 insertions, 1 deletions
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 5adc2fb62b0f..9410ec462ba6 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -691,8 +691,21 @@ int jbd2_log_wait_commit(journal_t *journal, tid_t tid)
{
int err = 0;
- jbd2_might_wait_for_commit(journal);
read_lock(&journal->j_state_lock);
+#ifdef CONFIG_PROVE_LOCKING
+ /*
+ * Some callers make sure transaction is already committing and in that
+ * case we cannot block on open handles anymore. So don't warn in that
+ * case.
+ */
+ if (tid_gt(tid, journal->j_commit_sequence) &&
+ (!journal->j_committing_transaction ||
+ journal->j_committing_transaction->t_tid != tid)) {
+ read_unlock(&journal->j_state_lock);
+ jbd2_might_wait_for_commit(journal);
+ read_lock(&journal->j_state_lock);
+ }
+#endif
#ifdef CONFIG_JBD2_DEBUG
if (!tid_geq(journal->j_commit_request, tid)) {
printk(KERN_ERR