From e44718318004a5618d1dfe2d080e2862532d8e5f Mon Sep 17 00:00:00 2001 From: Theodore Ts'o Date: Sat, 12 Feb 2011 08:18:24 -0500 Subject: jbd2: call __jbd2_log_start_commit with j_state_lock write locked On an SMP ARM system running ext4, I've received a report that the first J_ASSERT in jbd2_journal_commit_transaction has been triggering: J_ASSERT(journal->j_running_transaction != NULL); While investigating possible causes for this problem, I noticed that __jbd2_log_start_commit() is getting called with j_state_lock only read-locked, in spite of the fact that it's possible for it might j_commit_request. Fix this by grabbing the necessary information so we can test to see if we need to start a new transaction before dropping the read lock, and then calling jbd2_log_start_commit() which will grab the write lock. Signed-off-by: "Theodore Ts'o" --- fs/jbd2/journal.c | 9 +++++++-- fs/jbd2/transaction.c | 21 ++++++++++++++------- 2 files changed, 21 insertions(+), 9 deletions(-) (limited to 'fs/jbd2') diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c index 9e46869..97e7346 100644 --- a/fs/jbd2/journal.c +++ b/fs/jbd2/journal.c @@ -473,7 +473,8 @@ int __jbd2_log_space_left(journal_t *journal) } /* - * Called under j_state_lock. Returns true if a transaction commit was started. + * Called with j_state_lock locked for writing. + * Returns true if a transaction commit was started. */ int __jbd2_log_start_commit(journal_t *journal, tid_t target) { @@ -520,11 +521,13 @@ int jbd2_journal_force_commit_nested(journal_t *journal) { transaction_t *transaction = NULL; tid_t tid; + int need_to_start = 0; read_lock(&journal->j_state_lock); if (journal->j_running_transaction && !current->journal_info) { transaction = journal->j_running_transaction; - __jbd2_log_start_commit(journal, transaction->t_tid); + if (!tid_geq(journal->j_commit_request, transaction->t_tid)) + need_to_start = 1; } else if (journal->j_committing_transaction) transaction = journal->j_committing_transaction; @@ -535,6 +538,8 @@ int jbd2_journal_force_commit_nested(journal_t *journal) tid = transaction->t_tid; read_unlock(&journal->j_state_lock); + if (need_to_start) + jbd2_log_start_commit(journal, tid); jbd2_log_wait_commit(journal, tid); return 1; } diff --git a/fs/jbd2/transaction.c b/fs/jbd2/transaction.c index faad2bd..1d11910 100644 --- a/fs/jbd2/transaction.c +++ b/fs/jbd2/transaction.c @@ -117,10 +117,10 @@ static inline void update_t_max_wait(transaction_t *transaction) static int start_this_handle(journal_t *journal, handle_t *handle, int gfp_mask) { - transaction_t *transaction; - int needed; - int nblocks = handle->h_buffer_credits; - transaction_t *new_transaction = NULL; + transaction_t *transaction, *new_transaction = NULL; + tid_t tid; + int needed, need_to_start; + int nblocks = handle->h_buffer_credits; if (nblocks > journal->j_max_transaction_buffers) { printk(KERN_ERR "JBD: %s wants too many credits (%d > %d)\n", @@ -222,8 +222,11 @@ repeat: atomic_sub(nblocks, &transaction->t_outstanding_credits); prepare_to_wait(&journal->j_wait_transaction_locked, &wait, TASK_UNINTERRUPTIBLE); - __jbd2_log_start_commit(journal, transaction->t_tid); + tid = transaction->t_tid; + need_to_start = !tid_geq(journal->j_commit_request, tid); read_unlock(&journal->j_state_lock); + if (need_to_start) + jbd2_log_start_commit(journal, tid); schedule(); finish_wait(&journal->j_wait_transaction_locked, &wait); goto repeat; @@ -442,7 +445,8 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask) { transaction_t *transaction = handle->h_transaction; journal_t *journal = transaction->t_journal; - int ret; + tid_t tid; + int need_to_start, ret; /* If we've had an abort of any type, don't even think about * actually doing the restart! */ @@ -465,8 +469,11 @@ int jbd2__journal_restart(handle_t *handle, int nblocks, int gfp_mask) spin_unlock(&transaction->t_handle_lock); jbd_debug(2, "restarting handle %p\n", handle); - __jbd2_log_start_commit(journal, transaction->t_tid); + tid = transaction->t_tid; + need_to_start = !tid_geq(journal->j_commit_request, tid); read_unlock(&journal->j_state_lock); + if (need_to_start) + jbd2_log_start_commit(journal, tid); lock_map_release(&handle->h_lockdep_map); handle->h_buffer_credits = nblocks; -- cgit v1.1