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/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
* and limitations under the License.
*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* Copyright (c) 2013 by Delphix. All rights reserved.
*/
#ifndef _SYS_METASLAB_IMPL_H
#define _SYS_METASLAB_IMPL_H
#include <sys/metaslab.h>
#include <sys/space_map.h>
#include <sys/range_tree.h>
#include <sys/vdev.h>
#include <sys/txg.h>
#include <sys/avl.h>
#ifdef __cplusplus
extern "C" {
#endif
struct metaslab_class {
spa_t *mc_spa;
metaslab_group_t *mc_rotor;
metaslab_ops_t *mc_ops;
uint64_t mc_aliquot;
uint64_t mc_alloc_groups; /* # of allocatable groups */
uint64_t mc_alloc; /* total allocated space */
uint64_t mc_deferred; /* total deferred frees */
uint64_t mc_space; /* total space (alloc + free) */
uint64_t mc_dspace; /* total deflated space */
kmutex_t mc_fastwrite_lock;
};
struct metaslab_group {
kmutex_t mg_lock;
avl_tree_t mg_metaslab_tree;
uint64_t mg_aliquot;
uint64_t mg_alloc_failures;
boolean_t mg_allocatable; /* can we allocate? */
uint64_t mg_free_capacity; /* percentage free */
int64_t mg_bias;
int64_t mg_activation_count;
metaslab_class_t *mg_class;
vdev_t *mg_vd;
taskq_t *mg_taskq;
metaslab_group_t *mg_prev;
metaslab_group_t *mg_next;
};
/*
* This value defines the number of elements in the ms_lbas array. The value
* of 64 was chosen as it covers to cover all power of 2 buckets up to
* UINT64_MAX. This is the equivalent of highbit(UINT64_MAX).
*/
#define MAX_LBAS 64
/*
* Each metaslab maintains a set of in-core trees to track metaslab operations.
* The in-core free tree (ms_tree) contains the current list of free segments.
* As blocks are allocated, the allocated segment are removed from the ms_tree
* and added to a per txg allocation tree (ms_alloctree). As blocks are freed,
* they are added to the per txg free tree (ms_freetree). These per txg
* trees allow us to process all allocations and frees in syncing context
* where it is safe to update the on-disk space maps. One additional in-core
* tree is maintained to track deferred frees (ms_defertree). Once a block
* is freed it will move from the ms_freetree to the ms_defertree. A deferred
* free means that a block has been freed but cannot be used by the pool
* until TXG_DEFER_SIZE transactions groups later. For example, a block
* that is freed in txg 50 will not be available for reallocation until
* txg 52 (50 + TXG_DEFER_SIZE). This provides a safety net for uberblock
* rollback. A pool could be safely rolled back TXG_DEFERS_SIZE
* transactions groups and ensure that no block has been reallocated.
*
* The simplified transition diagram looks like this:
*
*
* ALLOCATE
* |
* V
* free segment (ms_tree) --------> ms_alloctree ----> (write to space map)
* ^
* |
* | ms_freetree <--- FREE
* | |
* | |
* | |
* +----------- ms_defertree <-------+---------> (write to space map)
*
*
* Each metaslab's space is tracked in a single space map in the MOS,
* which is only updated in syncing context. Each time we sync a txg,
* we append the allocs and frees from that txg to the space map.
* The pool space is only updated once all metaslabs have finished syncing.
*
* To load the in-core free tree we read the space map from disk.
* This object contains a series of alloc and free records that are
* combined to make up the list of all free segments in this metaslab. These
* segments are represented in-core by the ms_tree and are stored in an
* AVL tree.
*
* As the space map grows (as a result of the appends) it will
* eventually become space-inefficient. When the metaslab's in-core free tree
* is zfs_condense_pct/100 times the size of the minimal on-disk
* representation, we rewrite it in its minimized form. If a metaslab
* needs to condense then we must set the ms_condensing flag to ensure
* that allocations are not performed on the metaslab that is being written.
*/
struct metaslab {
kmutex_t ms_lock;
kcondvar_t ms_load_cv;
space_map_t *ms_sm;
metaslab_ops_t *ms_ops;
uint64_t ms_id;
uint64_t ms_start;
uint64_t ms_size;
range_tree_t *ms_alloctree[TXG_SIZE];
range_tree_t *ms_freetree[TXG_SIZE];
range_tree_t *ms_defertree[TXG_DEFER_SIZE];
range_tree_t *ms_tree;
boolean_t ms_condensing; /* condensing? */
boolean_t ms_loaded;
boolean_t ms_loading;
int64_t ms_deferspace; /* sum of ms_defermap[] space */
uint64_t ms_weight; /* weight vs. others in group */
uint64_t ms_factor;
uint64_t ms_access_txg;
/*
* The metaslab block allocators can optionally use a size-ordered
* range tree and/or an array of LBAs. Not all allocators use
* this functionality. The ms_size_tree should always contain the
* same number of segments as the ms_tree. The only difference
* is that the ms_size_tree is ordered by segment sizes.
*/
avl_tree_t ms_size_tree;
uint64_t ms_lbas[MAX_LBAS];
metaslab_group_t *ms_group; /* metaslab group */
avl_node_t ms_group_node; /* node in metaslab group tree */
txg_node_t ms_txg_node; /* per-txg dirty metaslab links */
};
#ifdef __cplusplus
}
#endif
#endif /* _SYS_METASLAB_IMPL_H */
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