diff options
Diffstat (limited to 'module/zfs/zil.c')
| -rw-r--r-- | module/zfs/zil.c | 215 |
1 files changed, 129 insertions, 86 deletions
diff --git a/module/zfs/zil.c b/module/zfs/zil.c index b5685d73b..81bc6de41 100644 --- a/module/zfs/zil.c +++ b/module/zfs/zil.c @@ -57,7 +57,7 @@ * * In the event of a crash or power loss, the itxs contained by each * dataset's on-disk ZIL will be replayed when that dataset is first - * instantianted (e.g. if the dataset is a normal fileystem, when it is + * instantiated (e.g. if the dataset is a normal fileystem, when it is * first mounted). * * As hinted at above, there is one ZIL per dataset (both the in-memory @@ -539,8 +539,8 @@ zil_alloc_lwb(zilog_t *zilog, blkptr_t *bp, boolean_t slog, uint64_t txg, ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); - ASSERT(list_is_empty(&lwb->lwb_waiters)); - ASSERT(list_is_empty(&lwb->lwb_itxs)); + VERIFY(list_is_empty(&lwb->lwb_waiters)); + VERIFY(list_is_empty(&lwb->lwb_itxs)); return (lwb); } @@ -550,40 +550,14 @@ zil_free_lwb(zilog_t *zilog, lwb_t *lwb) { ASSERT(MUTEX_HELD(&zilog->zl_lock)); ASSERT(!MUTEX_HELD(&lwb->lwb_vdev_lock)); - ASSERT(list_is_empty(&lwb->lwb_waiters)); - - if (lwb->lwb_state == LWB_STATE_OPENED) { - avl_tree_t *t = &lwb->lwb_vdev_tree; - void *cookie = NULL; - zil_vdev_node_t *zv; - itx_t *itx; - - while ((zv = avl_destroy_nodes(t, &cookie)) != NULL) - kmem_free(zv, sizeof (*zv)); - - while ((itx = list_head(&lwb->lwb_itxs)) != NULL) { - if (itx->itx_callback != NULL) - itx->itx_callback(itx->itx_callback_data); - list_remove(&lwb->lwb_itxs, itx); - zil_itx_destroy(itx); - } - - ASSERT3P(lwb->lwb_root_zio, !=, NULL); - ASSERT3P(lwb->lwb_write_zio, !=, NULL); - - zio_cancel(lwb->lwb_root_zio); - zio_cancel(lwb->lwb_write_zio); - - lwb->lwb_root_zio = NULL; - lwb->lwb_write_zio = NULL; - } else { - ASSERT3S(lwb->lwb_state, !=, LWB_STATE_ISSUED); - } - + VERIFY(list_is_empty(&lwb->lwb_waiters)); + VERIFY(list_is_empty(&lwb->lwb_itxs)); ASSERT(avl_is_empty(&lwb->lwb_vdev_tree)); - ASSERT(list_is_empty(&lwb->lwb_itxs)); ASSERT3P(lwb->lwb_write_zio, ==, NULL); ASSERT3P(lwb->lwb_root_zio, ==, NULL); + ASSERT3U(lwb->lwb_max_txg, <=, spa_syncing_txg(zilog->zl_spa)); + ASSERT(lwb->lwb_state == LWB_STATE_CLOSED || + lwb->lwb_state == LWB_STATE_DONE); /* * Clear the zilog's field to indicate this lwb is no longer @@ -708,7 +682,7 @@ zil_create(zilog_t *zilog) /* * If we just allocated the first log block, commit our transaction - * and wait for zil_sync() to stuff the block poiner into zh_log. + * and wait for zil_sync() to stuff the block pointer into zh_log. * (zh is part of the MOS, so we cannot modify it in open context.) */ if (tx != NULL) { @@ -940,6 +914,12 @@ zil_commit_waiter_skip(zil_commit_waiter_t *zcw) static void zil_commit_waiter_link_lwb(zil_commit_waiter_t *zcw, lwb_t *lwb) { + /* + * The lwb_waiters field of the lwb is protected by the zilog's + * zl_lock, thus it must be held when calling this function. + */ + ASSERT(MUTEX_HELD(&lwb->lwb_zilog->zl_lock)); + mutex_enter(&zcw->zcw_lock); ASSERT(!list_link_active(&zcw->zcw_node)); ASSERT3P(zcw->zcw_lwb, ==, NULL); @@ -1319,7 +1299,7 @@ zil_lwb_write_issue(zilog_t *zilog, lwb_t *lwb) * close. * - next find the maximum from the new suggested size and an array of * previous sizes. This lessens a picket fence effect of wrongly - * guesssing the size if we have a stream of say 2k, 64k, 2k, 64k + * guessing the size if we have a stream of say 2k, 64k, 2k, 64k * requests. * * Note we only write what is used, but we can't just allocate @@ -1422,8 +1402,10 @@ zil_lwb_commit(zilog_t *zilog, itx_t *itx, lwb_t *lwb) * For more details, see the comment above zil_commit(). */ if (lrc->lrc_txtype == TX_COMMIT) { + mutex_enter(&zilog->zl_lock); zil_commit_waiter_link_lwb(itx->itx_private, lwb); itx->itx_private = NULL; + mutex_exit(&zilog->zl_lock); return (lwb); } @@ -2056,16 +2038,54 @@ zil_process_commit_list(zilog_t *zilog) list_remove(&zilog->zl_itx_commit_list, itx); - /* - * This is inherently racy and may result in us writing - * out a log block for a txg that was just synced. This - * is ok since we'll end cleaning up that log block the - * next time we call zil_sync(). - */ boolean_t synced = txg <= spa_last_synced_txg(spa); boolean_t frozen = txg > spa_freeze_txg(spa); - if (!synced || frozen) { + /* + * If the txg of this itx has already been synced out, then + * we don't need to commit this itx to an lwb. This is + * because the data of this itx will have already been + * written to the main pool. This is inherently racy, and + * it's still ok to commit an itx whose txg has already + * been synced; this will result in a write that's + * unnecessary, but will do no harm. + * + * With that said, we always want to commit TX_COMMIT itxs + * to an lwb, regardless of whether or not that itx's txg + * has been synced out. We do this to ensure any OPENED lwb + * will always have at least one zil_commit_waiter_t linked + * to the lwb. + * + * As a counter-example, if we skipped TX_COMMIT itx's + * whose txg had already been synced, the following + * situation could occur if we happened to be racing with + * spa_sync: + * + * 1. We commit a non-TX_COMMIT itx to an lwb, where the + * itx's txg is 10 and the last synced txg is 9. + * 2. spa_sync finishes syncing out txg 10. + * 3. We move to the next itx in the list, it's a TX_COMMIT + * whose txg is 10, so we skip it rather than committing + * it to the lwb used in (1). + * + * If the itx that is skipped in (3) is the last TX_COMMIT + * itx in the commit list, than it's possible for the lwb + * used in (1) to remain in the OPENED state indefinitely. + * + * To prevent the above scenario from occurring, ensuring + * that once an lwb is OPENED it will transition to ISSUED + * and eventually DONE, we always commit TX_COMMIT itx's to + * an lwb here, even if that itx's txg has already been + * synced. + * + * Finally, if the pool is frozen, we _always_ commit the + * itx. The point of freezing the pool is to prevent data + * from being written to the main pool via spa_sync, and + * instead rely solely on the ZIL to persistently store the + * data; i.e. when the pool is frozen, the last synced txg + * value can't be trusted. + */ + if (frozen || !synced || lrc->lrc_txtype == TX_COMMIT) { if (lwb != NULL) { lwb = zil_lwb_commit(zilog, itx, lwb); @@ -2082,20 +2102,7 @@ zil_process_commit_list(zilog_t *zilog) list_insert_tail(&nolwb_itxs, itx); } } else { - /* - * If this is a commit itx, then there will be a - * thread that is either: already waiting for - * it, or soon will be waiting. - * - * This itx has already been committed to disk - * via spa_sync() so we don't bother committing - * it to an lwb. As a result, we cannot use the - * lwb zio callback to signal the waiter and - * mark it as done, so we must do that here. - */ - if (lrc->lrc_txtype == TX_COMMIT) - zil_commit_waiter_skip(itx->itx_private); - + ASSERT3S(lrc->lrc_txtype, !=, TX_COMMIT); zil_itx_destroy(itx); } } @@ -2141,37 +2148,37 @@ zil_process_commit_list(zilog_t *zilog) * variable is in one of the following states: "closed" * or "open". * - * If its "closed", then no itxs have been committed to - * it, so there's no point in issueing its zio (i.e. - * it's "empty"). + * If it's "closed", then no itxs have been committed to + * it, so there's no point in issuing its zio (i.e. it's + * "empty"). * - * If its "open" state, then it contains one or more - * itxs that eventually need to be committed to stable - * storage. In this case we intentionally do not issue - * the lwb's zio to disk yet, and instead rely on one of - * the following two mechanisms for issuing the zio: + * If it's "open", then it contains one or more itxs that + * eventually need to be committed to stable storage. In + * this case we intentionally do not issue the lwb's zio + * to disk yet, and instead rely on one of the following + * two mechanisms for issuing the zio: * - * 1. Ideally, there will be more ZIL activity occuring + * 1. Ideally, there will be more ZIL activity occurring * on the system, such that this function will be - * immeidately called again (not necessarily by the same + * immediately called again (not necessarily by the same * thread) and this lwb's zio will be issued via * zil_lwb_commit(). This way, the lwb is guaranteed to * be "full" when it is issued to disk, and we'll make * use of the lwb's size the best we can. * - * 2. If there isn't sufficient ZIL activity occuring on + * 2. If there isn't sufficient ZIL activity occurring on * the system, such that this lwb's zio isn't issued via * zil_lwb_commit(), zil_commit_waiter() will issue the * lwb's zio. If this occurs, the lwb is not guaranteed * to be "full" by the time its zio is issued, and means * the size of the lwb was "too large" given the amount - * of ZIL activity occuring on the system at that time. + * of ZIL activity occurring on the system at that time. * * We do this for a couple of reasons: * * 1. To try and reduce the number of IOPs needed to * write the same number of itxs. If an lwb has space - * available in it's buffer for more itxs, and more itxs + * available in its buffer for more itxs, and more itxs * will be committed relatively soon (relative to the * latency of performing a write), then it's beneficial * to wait for these "next" itxs. This way, more itxs @@ -2193,7 +2200,7 @@ zil_process_commit_list(zilog_t *zilog) * itxs will be processed. The assumption is the passed in waiter's * commit itx will found in the queue just like the other non-commit * itxs, such that when the entire queue is processed, the waiter will - * have been commited to an lwb. + * have been committed to an lwb. * * The lwb associated with the passed in waiter is not guaranteed to * have been issued by the time this function completes. If the lwb is @@ -2205,7 +2212,6 @@ zil_commit_writer(zilog_t *zilog, zil_commit_waiter_t *zcw) { ASSERT(!MUTEX_HELD(&zilog->zl_lock)); ASSERT(spa_writeable(zilog->zl_spa)); - ASSERT0(zilog->zl_suspend); mutex_enter(&zilog->zl_issuer_lock); @@ -2265,7 +2271,7 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw) * In order to call zil_lwb_write_issue() we must hold the * zilog's "zl_issuer_lock". We can't simply acquire that lock, * since we're already holding the commit waiter's "zcw_lock", - * and those two locks are aquired in the opposite order + * and those two locks are acquired in the opposite order * elsewhere. */ mutex_exit(&zcw->zcw_lock); @@ -2286,10 +2292,24 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw) ASSERT3P(lwb, ==, zcw->zcw_lwb); /* - * We've already checked this above, but since we hadn't - * acquired the zilog's zl_issuer_lock, we have to perform this - * check a second time while holding the lock. We can't call + * We've already checked this above, but since we hadn't acquired + * the zilog's zl_issuer_lock, we have to perform this check a + * second time while holding the lock. + * + * We don't need to hold the zl_lock since the lwb cannot transition + * from OPENED to ISSUED while we hold the zl_issuer_lock. The lwb + * _can_ transition from ISSUED to DONE, but it's OK to race with + * that transition since we treat the lwb the same, whether it's in + * the ISSUED or DONE states. + * + * The important thing, is we treat the lwb differently depending on + * if it's ISSUED or OPENED, and block any other threads that might + * attempt to issue this lwb. For that reason we hold the + * zl_issuer_lock when checking the lwb_state; we must not call * zil_lwb_write_issue() if the lwb had already been issued. + * + * See the comment above the lwb_state_t structure definition for + * more details on the lwb states, and locking requirements. */ if (lwb->lwb_state == LWB_STATE_ISSUED || lwb->lwb_state == LWB_STATE_DONE) @@ -2315,7 +2335,7 @@ zil_commit_waiter_timeout(zilog_t *zilog, zil_commit_waiter_t *zcw) * By having to issue the lwb's zio here, it means the size of the * lwb was too large, given the incoming throughput of itxs. By * setting "zl_cur_used" to zero, we communicate this fact to the - * block size selection algorithm, so it can take this informaiton + * block size selection algorithm, so it can take this information * into account, and potentially select a smaller size for the * next lwb block that is allocated. */ @@ -2379,7 +2399,6 @@ zil_commit_waiter(zilog_t *zilog, zil_commit_waiter_t *zcw) ASSERT(!MUTEX_HELD(&zilog->zl_lock)); ASSERT(!MUTEX_HELD(&zilog->zl_issuer_lock)); ASSERT(spa_writeable(zilog->zl_spa)); - ASSERT0(zilog->zl_suspend); mutex_enter(&zcw->zcw_lock); @@ -2459,7 +2478,7 @@ zil_commit_waiter(zilog_t *zilog, zil_commit_waiter_t *zcw) * complete. * * Additionally, if the lwb is NULL, the waiter - * will soon be signalled and marked done via + * will soon be signaled and marked done via * zil_clean() and zil_itxg_clean(), so no timeout * is required. */ @@ -2560,7 +2579,7 @@ zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw) * When a thread calls zil_commit() a special "commit itx" will be * generated, along with a corresponding "waiter" for this commit itx. * zil_commit() will wait on this waiter's CV, such that when the waiter - * is marked done, and signalled, zil_commit() will return. + * is marked done, and signaled, zil_commit() will return. * * This commit itx is inserted into the queue of uncommitted itxs. This * provides an easy mechanism for determining which itxs were in the @@ -2570,7 +2589,7 @@ zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw) * The commit it is special; it doesn't have any on-disk representation. * When a commit itx is "committed" to an lwb, the waiter associated * with it is linked onto the lwb's list of waiters. Then, when that lwb - * completes, each waiter on the lwb's list is marked done and signalled + * completes, each waiter on the lwb's list is marked done and signaled * -- allowing the thread waiting on the waiter to return from zil_commit(). * * It's important to point out a few critical factors that allow us @@ -2578,10 +2597,10 @@ zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw) * commit waiters, and zio completion callbacks like we're doing: * * 1. The list of waiters for each lwb is traversed, and each commit - * waiter is marked "done" and signalled, in the zio completion + * waiter is marked "done" and signaled, in the zio completion * callback of the lwb's zio[*]. * - * * Actually, the waiters are signalled in the zio completion + * * Actually, the waiters are signaled in the zio completion * callback of the root zio for the DKIOCFLUSHWRITECACHE commands * that are sent to the vdevs upon completion of the lwb zio. * @@ -2629,7 +2648,7 @@ zil_commit_itx_assign(zilog_t *zilog, zil_commit_waiter_t *zcw) * the zilog's "zl_issuer_lock", which ensures only a single * thread is creating and/or issuing lwb's at a time * 2. The "previous" lwb is a child of the "current" lwb - * (leveraging the zio parent-child depenency graph) + * (leveraging the zio parent-child dependency graph) * * By relying on this parent-child zio relationship, we can have * many lwb zio's concurrently issued to the underlying storage, @@ -2662,7 +2681,7 @@ zil_commit(zilog_t *zilog, uint64_t foid) * If the SPA is not writable, there should never be any * pending itxs waiting to be committed to disk. If that * weren't true, we'd skip writing those itxs out, and - * would break the sematics of zil_commit(); thus, we're + * would break the semantics of zil_commit(); thus, we're * verifying that truth before we return to the caller. */ ASSERT(list_is_empty(&zilog->zl_lwb_list)); @@ -2684,6 +2703,12 @@ zil_commit(zilog_t *zilog, uint64_t foid) return; } + zil_commit_impl(zilog, foid); +} + +void +zil_commit_impl(zilog_t *zilog, uint64_t foid) +{ ZIL_STAT_BUMP(zil_commit_count); /* @@ -3149,7 +3174,22 @@ zil_suspend(const char *osname, void **cookiep) zilog->zl_suspending = B_TRUE; mutex_exit(&zilog->zl_lock); - zil_commit(zilog, 0); + /* + * We need to use zil_commit_impl to ensure we wait for all + * LWB_STATE_OPENED and LWB_STATE_ISSUED lwbs to be committed + * to disk before proceeding. If we used zil_commit instead, it + * would just call txg_wait_synced(), because zl_suspend is set. + * txg_wait_synced() doesn't wait for these lwb's to be + * LWB_STATE_DONE before returning. + */ + zil_commit_impl(zilog, 0); + + /* + * Now that we've ensured all lwb's are LWB_STATE_DONE, we use + * txg_wait_synced() to ensure the data from the zilog has + * migrated to the main pool before calling zil_destroy(). + */ + txg_wait_synced(zilog->zl_dmu_pool, 0); zil_destroy(zilog, B_FALSE); @@ -3400,6 +3440,9 @@ EXPORT_SYMBOL(zil_set_sync); EXPORT_SYMBOL(zil_set_logbias); /* BEGIN CSTYLED */ +module_param(zfs_commit_timeout_pct, int, 0644); +MODULE_PARM_DESC(zfs_commit_timeout_pct, "ZIL block open timeout percentage"); + module_param(zil_replay_disable, int, 0644); MODULE_PARM_DESC(zil_replay_disable, "Disable intent logging replay"); |