OpenZFS 8373 - TXG_WAIT in ZIL commit path

Authored by: Andriy Gapon <avg@FreeBSD.org>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Approved by: Dan McDonald <danmcd@joyent.com>
Reviewed-by: George Melikov <mail@gmelikov.ru>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Ported-by: Giuseppe Di Natale <dinatale2@llnl.gov>

OpenZFS-issue: https://www.illumos.org/issues/8373
OpenZFS-commit: https://github.com/openzfs/openzfs/commit/7f04961
Closes #6403
This commit is contained in:
Andriy Gapon 2017-07-17 15:31:30 +03:00 committed by Brian Behlendorf
parent 0f69f42b43
commit e98b611725

View File

@ -1009,7 +1009,24 @@ zil_lwb_write_start(zilog_t *zilog, lwb_t *lwb)
* to clean up in the event of allocation failure or I/O failure.
*/
tx = dmu_tx_create(zilog->zl_os);
VERIFY(dmu_tx_assign(tx, TXG_WAIT) == 0);
/*
* Since we are not going to create any new dirty data and we can even
* help with clearing the existing dirty data, we should not be subject
* to the dirty data based delays.
* We (ab)use TXG_WAITED to bypass the delay mechanism.
* One side effect from using TXG_WAITED is that dmu_tx_assign() can
* fail if the pool is suspended. Those are dramatic circumstances,
* so we return NULL to signal that the normal ZIL processing is not
* possible and txg_wait_synced() should be used to ensure that the data
* is on disk.
*/
error = dmu_tx_assign(tx, TXG_WAITED);
if (error != 0) {
ASSERT3S(error, ==, EIO);
dmu_tx_abort(tx);
return (NULL);
}
dsl_dataset_dirty(dmu_objset_ds(zilog->zl_os), tx);
txg = dmu_tx_get_txg(tx);