4.9-stable review patch. If anyone has any objections, please let me know.
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From: Jan Kara jack@suse.cz
[ Upstream commit c52c47e4b4fbe4284602fc2ccbfc4a4d8dc05b49 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/jbd2/journal.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)
--- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -691,8 +691,21 @@ int jbd2_log_wait_commit(journal_t *jour { 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