diff options
Diffstat (limited to 'sys/contrib/openzfs/module/zfs/dmu_tx.c')
| -rw-r--r-- | sys/contrib/openzfs/module/zfs/dmu_tx.c | 16 |
1 files changed, 16 insertions, 0 deletions
diff --git a/sys/contrib/openzfs/module/zfs/dmu_tx.c b/sys/contrib/openzfs/module/zfs/dmu_tx.c index 0ebed4e6fbdf..73667915df0f 100644 --- a/sys/contrib/openzfs/module/zfs/dmu_tx.c +++ b/sys/contrib/openzfs/module/zfs/dmu_tx.c @@ -1012,6 +1012,22 @@ dmu_tx_unassign(dmu_tx_t *tx) * details on the throttle). This is used by the VFS operations, after * they have already called dmu_tx_wait() (though most likely on a * different tx). + * + * It is guaranteed that subsequent successful calls to dmu_tx_assign() + * will assign the tx to monotonically increasing txgs. Of course this is + * not strong monotonicity, because the same txg can be returned multiple + * times in a row. This guarantee holds both for subsequent calls from + * one thread and for multiple threads. For example, it is impossible to + * observe the following sequence of events: + * + * Thread 1 Thread 2 + * + * dmu_tx_assign(T1, ...) + * 1 <- dmu_tx_get_txg(T1) + * dmu_tx_assign(T2, ...) + * 2 <- dmu_tx_get_txg(T2) + * dmu_tx_assign(T3, ...) + * 1 <- dmu_tx_get_txg(T3) */ int dmu_tx_assign(dmu_tx_t *tx, uint64_t txg_how) |