/*
* 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).
*
* We cannot safely clean a transaction out of the log until all of the
* buffer updates committed in that transaction have safely been stored
* elsewhere on disk. To achieve this, all of the buffers in a
* transaction need to be maintained on the transaction's checkpoint
* lists until they have been rewritten, at which point this function is
* called to remove the buffer from the existing transaction's
* checkpoint lists.
*
* The function returns 1 if it frees the transaction, 0 otherwise.
* The function can free jh and bh.
*
* This function is called with j_list_lock held.
*/
int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
{
struct transaction_chp_stats_s *stats;
transaction_t *transaction;
journal_t *journal;
int ret = 0;
JBUFFER_TRACE(jh, "entry");
if ((transaction = jh->b_cp_transaction) == NULL) {
JBUFFER_TRACE(jh, "not on transaction");
goto out;
}
journal = transaction->t_journal;
JBUFFER_TRACE(jh, "removing from transaction");
__buffer_unlink(jh);
jh->b_cp_transaction = NULL;
jbd2_journal_put_journal_head(jh);
if (transaction->t_checkpoint_list != NULL ||
transaction->t_checkpoint_io_list != NULL)
goto out;
/*
* There is one special case to worry about: if we have just pulled the
* buffer off a running or committing transaction's checkpoing list,
* then even if the checkpoint list is empty, the transaction obviously
* cannot be dropped!
*
* The locking here around t_state is a bit sleazy.
* See the comment at the end of jbd2_journal_commit_transaction().
*/
if (transaction->t_state != T_FINISHED)
goto out;
/* OK, that was the last buffer for the transaction: we can now
safely remove this transaction from the log */
stats = &transaction->t_chp_stats;
if (stats->cs_chp_time)
stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
jiffies);
trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
transaction->t_tid, stats);
__jbd2_journal_drop_transaction(journal, transaction);
if ((journal->j_commit_callback == NULL) || (transaction->t_callbacked)) {
jbd2_journal_free_transaction(transaction);
} else {
transaction->t_dropped = 1;
}
/* Just in case anybody was waiting for more transactions to be
checkpointed... */
wake_up(&journal->j_wait_logspace);
ret = 1;
out:
return ret;
}
int __jbd2_journal_remove_checkpoint(struct journal_head *jh)
{
struct transaction_chp_stats_s *stats;
transaction_t *transaction;
journal_t *journal;
int ret = 0;
JBUFFER_TRACE(jh, "entry");
if ((transaction = jh->b_cp_transaction) == NULL) {
JBUFFER_TRACE(jh, "not on transaction");
goto out;
}
journal = transaction->t_journal;
JBUFFER_TRACE(jh, "removing from transaction");
__buffer_unlink(jh);
jh->b_cp_transaction = NULL;
jbd2_journal_put_journal_head(jh);
if (transaction->t_checkpoint_list != NULL ||
transaction->t_checkpoint_io_list != NULL)
goto out;
/*
*/
if (transaction->t_state != T_FINISHED)
goto out;
/*
*/
stats = &transaction->t_chp_stats;
if (stats->cs_chp_time)
stats->cs_chp_time = jbd2_time_diff(stats->cs_chp_time,
jiffies);
trace_jbd2_checkpoint_stats(journal->j_fs_dev->bd_dev,
transaction->t_tid, stats);
__jbd2_journal_drop_transaction(journal, transaction);
jbd2_journal_free_transaction(transaction);
/*
*/
wake_up(&journal->j_wait_logspace);
ret = 1;
out:
return ret;
}
static int start_this_handle(journal_t *journal, handle_t *handle,
gfp_t gfp_mask)
{
transaction_t *transaction, *new_transaction = NULL;
tid_t tid;
int needed, need_to_start;
int nblocks = handle->h_buffer_credits;
unsigned long ts = jiffies;
if (nblocks > journal->j_max_transaction_buffers) {
printk(KERN_ERR "JBD2: %s wants too many credits (%d > %d)\n",
current->comm, nblocks,
journal->j_max_transaction_buffers);
return -ENOSPC;
}
alloc_transaction:
if (!journal->j_running_transaction) {
new_transaction = kmem_cache_alloc(transaction_cache,
gfp_mask | __GFP_ZERO);
if (!new_transaction) {
if ((gfp_mask & __GFP_FS) == 0) {
congestion_wait(BLK_RW_ASYNC, HZ/50);
goto alloc_transaction;
}
return -ENOMEM;
}
}
jbd_debug(3, "New handle %p going live.\n", handle);
repeat:
read_lock(&journal->j_state_lock);
BUG_ON(journal->j_flags & JBD2_UNMOUNT);
if (is_journal_aborted(journal) ||
(journal->j_errno != 0 && !(journal->j_flags & JBD2_ACK_ERR))) {
read_unlock(&journal->j_state_lock);
jbd2_journal_free_transaction(new_transaction);
return -EROFS;
}
if (journal->j_barrier_count) {
read_unlock(&journal->j_state_lock);
wait_event(journal->j_wait_transaction_locked,
journal->j_barrier_count == 0);
goto repeat;
}
if (!journal->j_running_transaction) {
read_unlock(&journal->j_state_lock);
if (!new_transaction)
goto alloc_transaction;
write_lock(&journal->j_state_lock);
if (journal->j_barrier_count) {
printk(KERN_WARNING "JBD: %s: wait for transaction barrier\n", __func__);
write_unlock(&journal->j_state_lock);
goto repeat;
}
if (!journal->j_running_transaction) {
jbd2_get_transaction(journal, new_transaction);
new_transaction = NULL;
}
write_unlock(&journal->j_state_lock);
goto repeat;
}
transaction = journal->j_running_transaction;
if (transaction->t_state == T_LOCKED) {
DEFINE_WAIT(wait);
prepare_to_wait(&journal->j_wait_transaction_locked,
&wait, TASK_UNINTERRUPTIBLE);
read_unlock(&journal->j_state_lock);
schedule();
finish_wait(&journal->j_wait_transaction_locked, &wait);
goto repeat;
}
needed = atomic_add_return(nblocks,
&transaction->t_outstanding_credits);
if (needed > journal->j_max_transaction_buffers) {
DEFINE_WAIT(wait);
jbd_debug(2, "Handle %p starting new commit...\n", handle);
atomic_sub(nblocks, &transaction->t_outstanding_credits);
prepare_to_wait(&journal->j_wait_transaction_locked, &wait,
TASK_UNINTERRUPTIBLE);
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;
}
if (__jbd2_log_space_left(journal) < jbd_space_needed(journal)) {
jbd_debug(2, "Handle %p waiting for checkpoint...\n", handle);
atomic_sub(nblocks, &transaction->t_outstanding_credits);
read_unlock(&journal->j_state_lock);
write_lock(&journal->j_state_lock);
if (__jbd2_log_space_left(journal) < jbd_space_needed(journal))
__jbd2_log_wait_for_space(journal);
write_unlock(&journal->j_state_lock);
goto repeat;
}
update_t_max_wait(transaction, ts);
handle->h_transaction = transaction;
atomic_inc(&transaction->t_updates);
atomic_inc(&transaction->t_handle_count);
jbd_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
handle, nblocks,
atomic_read(&transaction->t_outstanding_credits),
__jbd2_log_space_left(journal));
read_unlock(&journal->j_state_lock);
lock_map_acquire(&handle->h_lockdep_map);
jbd2_journal_free_transaction(new_transaction);
return 0;
}
