244 lines
9.5 KiB
C
244 lines
9.5 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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* Copyright (c) 2012, 2017 by Delphix. All rights reserved.
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*/
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/* Portions Copyright 2010 Robert Milkowski */
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#ifndef _SYS_ZIL_IMPL_H
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#define _SYS_ZIL_IMPL_H
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#include <sys/zil.h>
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#include <sys/dmu_objset.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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/*
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* Possible states for a given lwb structure.
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*
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* An lwb will start out in the "closed" state, and then transition to
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* the "opened" state via a call to zil_lwb_write_open(). When
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* transitioning from "closed" to "opened" the zilog's "zl_issuer_lock"
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* must be held.
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*
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* After the lwb is "opened", it can transition into the "issued" state
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* via zil_lwb_write_issue(). Again, the zilog's "zl_issuer_lock" must
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* be held when making this transition.
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*
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* After the lwb's write zio completes, it transitions into the "write
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* done" state via zil_lwb_write_done(); and then into the "flush done"
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* state via zil_lwb_flush_vdevs_done(). When transitioning from
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* "issued" to "write done", and then from "write done" to "flush done",
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* the zilog's "zl_lock" must be held, *not* the "zl_issuer_lock".
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*
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* The zilog's "zl_issuer_lock" can become heavily contended in certain
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* workloads, so we specifically avoid acquiring that lock when
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* transitioning an lwb from "issued" to "done". This allows us to avoid
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* having to acquire the "zl_issuer_lock" for each lwb ZIO completion,
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* which would have added more lock contention on an already heavily
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* contended lock.
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*
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* Additionally, correctness when reading an lwb's state is often
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* achieved by exploiting the fact that these state transitions occur in
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* this specific order; i.e. "closed" to "opened" to "issued" to "done".
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*
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* Thus, if an lwb is in the "closed" or "opened" state, holding the
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* "zl_issuer_lock" will prevent a concurrent thread from transitioning
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* that lwb to the "issued" state. Likewise, if an lwb is already in the
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* "issued" state, holding the "zl_lock" will prevent a concurrent
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* thread from transitioning that lwb to the "write done" state.
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*/
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typedef enum {
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LWB_STATE_CLOSED,
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LWB_STATE_OPENED,
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LWB_STATE_ISSUED,
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LWB_STATE_WRITE_DONE,
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LWB_STATE_FLUSH_DONE,
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LWB_NUM_STATES
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} lwb_state_t;
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/*
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* Log write block (lwb)
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*
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* Prior to an lwb being issued to disk via zil_lwb_write_issue(), it
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* will be protected by the zilog's "zl_issuer_lock". Basically, prior
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* to it being issued, it will only be accessed by the thread that's
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* holding the "zl_issuer_lock". After the lwb is issued, the zilog's
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* "zl_lock" is used to protect the lwb against concurrent access.
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*/
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typedef struct lwb {
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zilog_t *lwb_zilog; /* back pointer to log struct */
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blkptr_t lwb_blk; /* on disk address of this log blk */
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boolean_t lwb_fastwrite; /* is blk marked for fastwrite? */
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boolean_t lwb_slog; /* lwb_blk is on SLOG device */
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int lwb_nused; /* # used bytes in buffer */
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int lwb_sz; /* size of block and buffer */
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lwb_state_t lwb_state; /* the state of this lwb */
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char *lwb_buf; /* log write buffer */
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zio_t *lwb_write_zio; /* zio for the lwb buffer */
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zio_t *lwb_root_zio; /* root zio for lwb write and flushes */
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dmu_tx_t *lwb_tx; /* tx for log block allocation */
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uint64_t lwb_max_txg; /* highest txg in this lwb */
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list_node_t lwb_node; /* zilog->zl_lwb_list linkage */
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list_t lwb_itxs; /* list of itx's */
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list_t lwb_waiters; /* list of zil_commit_waiter's */
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avl_tree_t lwb_vdev_tree; /* vdevs to flush after lwb write */
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kmutex_t lwb_vdev_lock; /* protects lwb_vdev_tree */
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hrtime_t lwb_issued_timestamp; /* when was the lwb issued? */
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} lwb_t;
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/*
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* ZIL commit waiter.
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*
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* This structure is allocated each time zil_commit() is called, and is
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* used by zil_commit() to communicate with other parts of the ZIL, such
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* that zil_commit() can know when it safe for it return. For more
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* details, see the comment above zil_commit().
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*
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* The "zcw_lock" field is used to protect the commit waiter against
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* concurrent access. This lock is often acquired while already holding
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* the zilog's "zl_issuer_lock" or "zl_lock"; see the functions
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* zil_process_commit_list() and zil_lwb_flush_vdevs_done() as examples
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* of this. Thus, one must be careful not to acquire the
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* "zl_issuer_lock" or "zl_lock" when already holding the "zcw_lock";
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* e.g. see the zil_commit_waiter_timeout() function.
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*/
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typedef struct zil_commit_waiter {
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kcondvar_t zcw_cv; /* signalled when "done" */
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kmutex_t zcw_lock; /* protects fields of this struct */
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list_node_t zcw_node; /* linkage in lwb_t:lwb_waiter list */
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lwb_t *zcw_lwb; /* back pointer to lwb when linked */
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boolean_t zcw_done; /* B_TRUE when "done", else B_FALSE */
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int zcw_zio_error; /* contains the zio io_error value */
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} zil_commit_waiter_t;
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/*
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* Intent log transaction lists
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*/
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typedef struct itxs {
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list_t i_sync_list; /* list of synchronous itxs */
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avl_tree_t i_async_tree; /* tree of foids for async itxs */
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} itxs_t;
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typedef struct itxg {
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kmutex_t itxg_lock; /* lock for this structure */
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uint64_t itxg_txg; /* txg for this chain */
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itxs_t *itxg_itxs; /* sync and async itxs */
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} itxg_t;
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/* for async nodes we build up an AVL tree of lists of async itxs per file */
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typedef struct itx_async_node {
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uint64_t ia_foid; /* file object id */
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list_t ia_list; /* list of async itxs for this foid */
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avl_node_t ia_node; /* AVL tree linkage */
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} itx_async_node_t;
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/*
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* Vdev flushing: during a zil_commit(), we build up an AVL tree of the vdevs
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* we've touched so we know which ones need a write cache flush at the end.
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*/
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typedef struct zil_vdev_node {
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uint64_t zv_vdev; /* vdev to be flushed */
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avl_node_t zv_node; /* AVL tree linkage */
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} zil_vdev_node_t;
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#define ZIL_PREV_BLKS 16
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/*
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* Stable storage intent log management structure. One per dataset.
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*/
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struct zilog {
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kmutex_t zl_lock; /* protects most zilog_t fields */
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struct dsl_pool *zl_dmu_pool; /* DSL pool */
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spa_t *zl_spa; /* handle for read/write log */
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const zil_header_t *zl_header; /* log header buffer */
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objset_t *zl_os; /* object set we're logging */
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zil_get_data_t *zl_get_data; /* callback to get object content */
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lwb_t *zl_last_lwb_opened; /* most recent lwb opened */
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hrtime_t zl_last_lwb_latency; /* zio latency of last lwb done */
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uint64_t zl_lr_seq; /* on-disk log record sequence number */
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uint64_t zl_commit_lr_seq; /* last committed on-disk lr seq */
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uint64_t zl_destroy_txg; /* txg of last zil_destroy() */
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uint64_t zl_replayed_seq[TXG_SIZE]; /* last replayed rec seq */
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uint64_t zl_replaying_seq; /* current replay seq number */
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uint32_t zl_suspend; /* log suspend count */
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kcondvar_t zl_cv_suspend; /* log suspend completion */
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uint8_t zl_suspending; /* log is currently suspending */
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uint8_t zl_keep_first; /* keep first log block in destroy */
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uint8_t zl_replay; /* replaying records while set */
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uint8_t zl_stop_sync; /* for debugging */
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kmutex_t zl_issuer_lock; /* single writer, per ZIL, at a time */
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uint8_t zl_logbias; /* latency or throughput */
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uint8_t zl_sync; /* synchronous or asynchronous */
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int zl_parse_error; /* last zil_parse() error */
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uint64_t zl_parse_blk_seq; /* highest blk seq on last parse */
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uint64_t zl_parse_lr_seq; /* highest lr seq on last parse */
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uint64_t zl_parse_blk_count; /* number of blocks parsed */
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uint64_t zl_parse_lr_count; /* number of log records parsed */
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itxg_t zl_itxg[TXG_SIZE]; /* intent log txg chains */
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list_t zl_itx_commit_list; /* itx list to be committed */
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uint64_t zl_cur_used; /* current commit log size used */
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list_t zl_lwb_list; /* in-flight log write list */
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avl_tree_t zl_bp_tree; /* track bps during log parse */
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clock_t zl_replay_time; /* lbolt of when replay started */
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uint64_t zl_replay_blks; /* number of log blocks replayed */
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zil_header_t zl_old_header; /* debugging aid */
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uint_t zl_prev_blks[ZIL_PREV_BLKS]; /* size - sector rounded */
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uint_t zl_prev_rotor; /* rotor for zl_prev[] */
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txg_node_t zl_dirty_link; /* protected by dp_dirty_zilogs list */
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uint64_t zl_dirty_max_txg; /* highest txg used to dirty zilog */
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};
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typedef struct zil_bp_node {
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dva_t zn_dva;
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avl_node_t zn_node;
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} zil_bp_node_t;
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/*
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* Maximum amount of write data that can be put into single log block.
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*/
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#define ZIL_MAX_LOG_DATA (SPA_OLD_MAXBLOCKSIZE - sizeof (zil_chain_t) - \
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sizeof (lr_write_t))
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/*
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* Maximum amount of log space we agree to waste to reduce number of
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* WR_NEED_COPY chunks to reduce zl_get_data() overhead (~12%).
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*/
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#define ZIL_MAX_WASTE_SPACE (ZIL_MAX_LOG_DATA / 8)
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/*
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* Maximum amount of write data for WR_COPIED. Fall back to WR_NEED_COPY
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* as more space efficient if we can't fit at least two log records into
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* maximum sized log block.
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*/
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#define ZIL_MAX_COPIED_DATA ((SPA_OLD_MAXBLOCKSIZE - \
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sizeof (zil_chain_t)) / 2 - sizeof (lr_write_t))
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#ifdef __cplusplus
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}
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#endif
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#endif /* _SYS_ZIL_IMPL_H */
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