int
dsl_sync_task_group_wait(dsl_sync_task_group_t *dstg)
{
dmu_tx_t *tx;
uint64_t txg;
dsl_sync_task_t *dst;
top:
tx = dmu_tx_create_dd(dstg->dstg_pool->dp_mos_dir);
VERIFY(0 == dmu_tx_assign(tx, TXG_WAIT));
txg = dmu_tx_get_txg(tx);
/* Do a preliminary error check. */
dstg->dstg_err = 0;
#ifdef ZFS_DEBUG
/*
* Only check half the time, otherwise, the sync-context
* check will almost never fail.
*/
if (spa_get_random(2) == 0)
goto skip;
#endif
rw_enter(&dstg->dstg_pool->dp_config_rwlock, RW_READER);
for (dst = list_head(&dstg->dstg_tasks); dst;
dst = list_next(&dstg->dstg_tasks, dst)) {
dst->dst_err =
dst->dst_checkfunc(dst->dst_arg1, dst->dst_arg2, tx);
if (dst->dst_err)
dstg->dstg_err = dst->dst_err;
}
rw_exit(&dstg->dstg_pool->dp_config_rwlock);
if (dstg->dstg_err) {
dmu_tx_commit(tx);
return (dstg->dstg_err);
}
skip:
/*
* We don't generally have many sync tasks, so pay the price of
* add_tail to get the tasks executed in the right order.
*/
VERIFY(0 == txg_list_add_tail(&dstg->dstg_pool->dp_sync_tasks,
dstg, txg));
dmu_tx_commit(tx);
txg_wait_synced(dstg->dstg_pool, txg);
if (dstg->dstg_err == EAGAIN) {
txg_wait_synced(dstg->dstg_pool, txg + TXG_DEFER_SIZE);
goto top;
}
return (dstg->dstg_err);
}
/*
* Called from open context to perform a callback in syncing context. Waits
* for the operation to complete.
*
* The checkfunc will be called from open context as a preliminary check
* which can quickly fail. If it succeeds, it will be called again from
* syncing context. The checkfunc should generally be designed to work
* properly in either context, but if necessary it can check
* dmu_tx_is_syncing(tx).
*
* The synctask infrastructure enforces proper locking strategy with respect
* to the dp_config_rwlock -- the lock will always be held when the callbacks
* are called. It will be held for read during the open-context (preliminary)
* call to the checkfunc, and then held for write from syncing context during
* the calls to the check and sync funcs.
*
* A dataset or pool name can be passed as the first argument. Typically,
* the check func will hold, check the return value of the hold, and then
* release the dataset. The sync func will VERIFYO(hold()) the dataset.
* This is safe because no changes can be made between the check and sync funcs,
* and the sync func will only be called if the check func successfully opened
* the dataset.
*/
int
dsl_sync_task(const char *pool, dsl_checkfunc_t *checkfunc,
dsl_syncfunc_t *syncfunc, void *arg,
int blocks_modified, zfs_space_check_t space_check)
{
spa_t *spa;
dmu_tx_t *tx;
int err;
dsl_sync_task_t dst = { { { NULL } } };
dsl_pool_t *dp;
err = spa_open(pool, &spa, FTAG);
if (err != 0)
return (err);
dp = spa_get_dsl(spa);
top:
tx = dmu_tx_create_dd(dp->dp_mos_dir);
VERIFY0(dmu_tx_assign(tx, TXG_WAIT));
dst.dst_pool = dp;
dst.dst_txg = dmu_tx_get_txg(tx);
dst.dst_space = blocks_modified << DST_AVG_BLKSHIFT;
dst.dst_space_check = space_check;
dst.dst_checkfunc = checkfunc != NULL ? checkfunc : dsl_null_checkfunc;
dst.dst_syncfunc = syncfunc;
dst.dst_arg = arg;
dst.dst_error = 0;
dst.dst_nowaiter = B_FALSE;
dsl_pool_config_enter(dp, FTAG);
err = dst.dst_checkfunc(arg, tx);
dsl_pool_config_exit(dp, FTAG);
if (err != 0) {
dmu_tx_commit(tx);
spa_close(spa, FTAG);
return (err);
}
VERIFY(txg_list_add_tail(&dp->dp_sync_tasks, &dst, dst.dst_txg));
dmu_tx_commit(tx);
txg_wait_synced(dp, dst.dst_txg);
if (dst.dst_error == EAGAIN) {
txg_wait_synced(dp, dst.dst_txg + TXG_DEFER_SIZE);
goto top;
}
spa_close(spa, FTAG);
return (dst.dst_error);
}
void
dsl_sync_task_group_nowait(dsl_sync_task_group_t *dstg, dmu_tx_t *tx)
{
uint64_t txg;
dstg->dstg_nowaiter = B_TRUE;
txg = dmu_tx_get_txg(tx);
/*
* We don't generally have many sync tasks, so pay the price of
* add_tail to get the tasks executed in the right order.
*/
VERIFY(0 == txg_list_add_tail(&dstg->dstg_pool->dp_sync_tasks,
dstg, txg));
}
void
dsl_sync_task_nowait(dsl_pool_t *dp, dsl_syncfunc_t *syncfunc, void *arg,
int blocks_modified, dmu_tx_t *tx)
{
dsl_sync_task_t *dst = kmem_zalloc(sizeof (*dst), KM_SLEEP);
dst->dst_pool = dp;
dst->dst_txg = dmu_tx_get_txg(tx);
dst->dst_space = blocks_modified << DST_AVG_BLKSHIFT;
dst->dst_checkfunc = dsl_null_checkfunc;
dst->dst_syncfunc = syncfunc;
dst->dst_arg = arg;
dst->dst_error = 0;
dst->dst_nowaiter = B_TRUE;
VERIFY(txg_list_add_tail(&dp->dp_sync_tasks, dst, dst->dst_txg));
}
