void log_wait_for_space(journal_t *journal, int nblocks)
{
while (log_space_left(journal) < nblocks) {
if (journal->j_flags & JFS_ABORT)
return;
unlock_journal(journal);
down(&journal->j_checkpoint_sem);
lock_journal(journal);
/* Test again, another process may have checkpointed
* while we were waiting for the checkpoint lock */
if (log_space_left(journal) < nblocks) {
log_do_checkpoint(journal, nblocks);
}
up(&journal->j_checkpoint_sem);
}
}
int journal_extend (handle_t *handle, int nblocks)
{
transaction_t *transaction = handle->h_transaction;
journal_t *journal = transaction->t_journal;
int result = 1;
int wanted;
lock_journal (journal);
/* Don't extend a locked-down transaction! */
if (handle->h_transaction->t_state != T_RUNNING) {
jfs_debug(3, "denied handle %p %d blocks: "
"transaction not running\n", handle, nblocks);
goto error_out;
}
wanted = transaction->t_outstanding_credits + nblocks;
if (wanted > journal->j_max_transaction_buffers) {
jfs_debug(3, "denied handle %p %d blocks: "
"transaction too large\n", handle, nblocks);
goto error_out;
}
if (wanted > log_space_left(journal)) {
jfs_debug(3, "denied handle %p %d blocks: "
"insufficient log space\n", handle, nblocks);
goto error_out;
}
handle->h_buffer_credits += nblocks;
transaction->t_outstanding_credits += nblocks;
result = 0;
jfs_debug(3, "extended handle %p by %d\n", handle, nblocks);
error_out:
unlock_journal (journal);
return result;
}
static int start_this_handle(journal_t *journal, handle_t *handle)
{
transaction_t *transaction;
int needed;
int nblocks = handle->h_buffer_credits;
jfs_debug(4, "New handle %p going live.\n", handle);
repeat:
lock_journal(journal);
if ((journal->j_flags & JFS_ABORT) ||
(journal->j_errno != 0 && !(journal->j_flags & JFS_ACK_ERR))) {
unlock_journal(journal);
return -EROFS;
}
/* Wait on the journal's transaction barrier if necessary */
if (journal->j_barrier_count) {
unlock_journal(journal);
sleep_on(&journal->j_wait_transaction_locked);
goto repeat;
}
repeat_locked:
if (!journal->j_running_transaction)
get_transaction(journal);
/* @@@ Error? */
J_ASSERT(journal->j_running_transaction);
transaction = journal->j_running_transaction;
/* If the current transaction is locked down for commit, wait
* for the lock to be released. */
if (transaction->t_state == T_LOCKED) {
unlock_journal(journal);
jfs_debug(3, "Handle %p stalling...\n", handle);
sleep_on(&journal->j_wait_transaction_locked);
goto repeat;
}
/* If there is not enough space left in the log to write all
* potential buffers requested by this operation, we need to
* stall pending a log checkpoint to free some more log
* space. */
needed = transaction->t_outstanding_credits + nblocks;
if (needed > journal->j_max_transaction_buffers) {
/* If the current transaction is already too large, then
* start to commit it: we can then go back and attach
* this handle to a new transaction. */
jfs_debug(2, "Handle %p starting new commit...\n", handle);
log_start_commit(journal, transaction);
unlock_journal(journal);
sleep_on(&journal->j_wait_transaction_locked);
lock_journal(journal);
goto repeat_locked;
}
/*
* The commit code assumes that it can get enough log space
* without forcing a checkpoint. This is *critical* for
* correctness: a checkpoint of a buffer which is also
* associated with a committing transaction creates a deadlock,
* so commit simply cannot force through checkpoints.
*
* We must therefore ensure the necessary space in the journal
* *before* starting to dirty potentially checkpointed buffers
* in the new transaction.
*
* The worst part is, any transaction currently committing can
* reduce the free space arbitrarily. Be careful to account for
* those buffers when checkpointing.
*/
needed = journal->j_max_transaction_buffers;
if (journal->j_committing_transaction)
needed += journal->j_committing_transaction->t_outstanding_credits;
if (log_space_left(journal) < needed) {
jfs_debug(2, "Handle %p waiting for checkpoint...\n", handle);
log_wait_for_space(journal, needed);
goto repeat_locked;
}
/* OK, account for the buffers that this operation expects to
* use and add the handle to the running transaction. */
handle->h_transaction = transaction;
transaction->t_outstanding_credits += nblocks;
transaction->t_updates++;
jfs_debug(4, "Handle %p given %d credits (total %d, free %d)\n",
handle, nblocks, transaction->t_outstanding_credits,
log_space_left(journal));
unlock_journal(journal);
return 0;
}