#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.
+ * Each metaslab maintains a set of in-core trees to track metaslab
+ * operations. The in-core free tree (ms_tree) contains the list of
+ * free segments which are eligible for allocation. As blocks are
+ * allocated, the allocated segments are removed from the ms_tree and
+ * added to a per txg allocation tree (ms_alloctree). This allows us to
+ * process all allocations in syncing context where it is safe to update
+ * the on-disk space maps. Frees are also processed in syncing context.
+ * Most frees are generated from syncing context, and those that are not
+ * are held in the spa_free_bplist for processing in syncing context.
+ * An additional set of in-core trees is maintained to track deferred
+ * frees (ms_defertree). Once a block is freed it will move from the
+ * ms_freedtree 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)
+ * free segment (ms_tree) -----> ms_alloctree[4] ----> (write to space map)
* ^
- * |
- * | ms_freetree <--- FREE
- * | |
+ * | ms_freeingtree <--- FREE
* | |
+ * | v
+ * | ms_freedtree
* | |
- * +----------- ms_defertree <-------+---------> (write to space map)
+ * +-------- ms_defertree[2] <-------+---------> (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.
+ * 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
+ * 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.
+ * 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;
uint64_t ms_fragmentation;
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;
+ /*
+ * The following range trees are accessed only from syncing context.
+ * ms_free*tree only have entries while syncing, and are empty
+ * between syncs.
+ */
+ range_tree_t *ms_freeingtree; /* to free this syncing txg */
+ range_tree_t *ms_freedtree; /* already freed this syncing txg */
+ range_tree_t *ms_defertree[TXG_DEFER_SIZE];
+
boolean_t ms_condensing; /* condensing? */
boolean_t ms_condense_wanted;
{
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
uint64_t allocated = 0;
- uint64_t freed = 0;
uint64_t sm_free_space, msp_free_space;
int t;
allocated +=
range_tree_space(msp->ms_alloctree[(txg + t) & TXG_MASK]);
}
- freed = range_tree_space(msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK]);
msp_free_space = range_tree_space(msp->ms_tree) + allocated +
- msp->ms_deferspace + freed;
+ msp->ms_deferspace + range_tree_space(msp->ms_freedtree);
VERIFY3U(sm_free_space, ==, msp_free_space);
}
/*
* We create the main range tree here, but we don't create the
- * alloctree and freetree until metaslab_sync_done(). This serves
+ * other range trees until metaslab_sync_done(). This serves
* two purposes: it allows metaslab_sync_done() to detect the
* addition of new space; and for debugging, it ensures that we'd
* data fault on any attempt to use this metaslab before it's ready.
metaslab_unload(msp);
range_tree_destroy(msp->ms_tree);
+ range_tree_destroy(msp->ms_freeingtree);
+ range_tree_destroy(msp->ms_freedtree);
for (t = 0; t < TXG_SIZE; t++) {
range_tree_destroy(msp->ms_alloctree[t]);
- range_tree_destroy(msp->ms_freetree[t]);
}
for (t = 0; t < TXG_DEFER_SIZE; t++) {
metaslab_condense(metaslab_t *msp, uint64_t txg, dmu_tx_t *tx)
{
spa_t *spa = msp->ms_group->mg_vd->vdev_spa;
- range_tree_t *freetree = msp->ms_freetree[txg & TXG_MASK];
range_tree_t *condense_tree;
space_map_t *sm = msp->ms_sm;
int t;
/*
* Remove what's been freed in this txg from the condense_tree.
* Since we're in sync_pass 1, we know that all the frees from
- * this txg are in the freetree.
+ * this txg are in the freeingtree.
*/
- range_tree_walk(freetree, range_tree_remove, condense_tree);
+ range_tree_walk(msp->ms_freeingtree, range_tree_remove, condense_tree);
for (t = 0; t < TXG_DEFER_SIZE; t++) {
range_tree_walk(msp->ms_defertree[t],
spa_t *spa = vd->vdev_spa;
objset_t *mos = spa_meta_objset(spa);
range_tree_t *alloctree = msp->ms_alloctree[txg & TXG_MASK];
- range_tree_t **freetree = &msp->ms_freetree[txg & TXG_MASK];
- range_tree_t **freed_tree =
- &msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK];
dmu_tx_t *tx;
uint64_t object = space_map_object(msp->ms_sm);
/*
* This metaslab has just been added so there's no work to do now.
*/
- if (*freetree == NULL) {
+ if (msp->ms_freeingtree == NULL) {
ASSERT3P(alloctree, ==, NULL);
return;
}
ASSERT3P(alloctree, !=, NULL);
- ASSERT3P(*freetree, !=, NULL);
- ASSERT3P(*freed_tree, !=, NULL);
+ ASSERT3P(msp->ms_freeingtree, !=, NULL);
+ ASSERT3P(msp->ms_freedtree, !=, NULL);
/*
* Normally, we don't want to process a metaslab if there
* is being forced to condense we need to let it through.
*/
if (range_tree_space(alloctree) == 0 &&
- range_tree_space(*freetree) == 0 &&
+ range_tree_space(msp->ms_freeingtree) == 0 &&
!msp->ms_condense_wanted)
return;
/*
* The only state that can actually be changing concurrently with
* metaslab_sync() is the metaslab's ms_tree. No other thread can
- * be modifying this txg's alloctree, freetree, freed_tree, or
+ * be modifying this txg's alloctree, freeingtree, freedtree, or
* space_map_phys_t. Therefore, we only hold ms_lock to satify
* space map ASSERTs. We drop it whenever we call into the DMU,
* because the DMU can call down to us (e.g. via zio_free()) at
metaslab_condense(msp, txg, tx);
} else {
space_map_write(msp->ms_sm, alloctree, SM_ALLOC, tx);
- space_map_write(msp->ms_sm, *freetree, SM_FREE, tx);
+ space_map_write(msp->ms_sm, msp->ms_freeingtree, SM_FREE, tx);
}
if (msp->ms_loaded) {
* to accurately reflect all free space even if some space
* is not yet available for allocation (i.e. deferred).
*/
- space_map_histogram_add(msp->ms_sm, *freed_tree, tx);
+ space_map_histogram_add(msp->ms_sm, msp->ms_freedtree, tx);
/*
* Add back any deferred free space that has not been
* then we will lose some accuracy but will correct it the next
* time we load the space map.
*/
- space_map_histogram_add(msp->ms_sm, *freetree, tx);
+ space_map_histogram_add(msp->ms_sm, msp->ms_freeingtree, tx);
metaslab_group_histogram_add(mg, msp);
metaslab_group_histogram_verify(mg);
/*
* For sync pass 1, we avoid traversing this txg's free range tree
- * and instead will just swap the pointers for freetree and
- * freed_tree. We can safely do this since the freed_tree is
+ * and instead will just swap the pointers for freeingtree and
+ * freedtree. We can safely do this since the freed_tree is
* guaranteed to be empty on the initial pass.
*/
if (spa_sync_pass(spa) == 1) {
- range_tree_swap(freetree, freed_tree);
+ range_tree_swap(&msp->ms_freeingtree, &msp->ms_freedtree);
} else {
- range_tree_vacate(*freetree, range_tree_add, *freed_tree);
+ range_tree_vacate(msp->ms_freeingtree,
+ range_tree_add, msp->ms_freedtree);
}
range_tree_vacate(alloctree, NULL, NULL);
ASSERT0(range_tree_space(msp->ms_alloctree[txg & TXG_MASK]));
ASSERT0(range_tree_space(msp->ms_alloctree[TXG_CLEAN(txg) & TXG_MASK]));
- ASSERT0(range_tree_space(msp->ms_freetree[txg & TXG_MASK]));
+ ASSERT0(range_tree_space(msp->ms_freeingtree));
mutex_exit(&msp->ms_lock);
metaslab_group_t *mg = msp->ms_group;
vdev_t *vd = mg->mg_vd;
spa_t *spa = vd->vdev_spa;
- range_tree_t **freed_tree;
range_tree_t **defer_tree;
int64_t alloc_delta, defer_delta;
uint64_t free_space;
/*
* If this metaslab is just becoming available, initialize its
- * alloctrees, freetrees, and defertree and add its capacity to
- * the vdev.
+ * range trees and add its capacity to the vdev.
*/
- if (msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK] == NULL) {
+ if (msp->ms_freedtree == NULL) {
for (t = 0; t < TXG_SIZE; t++) {
ASSERT(msp->ms_alloctree[t] == NULL);
- ASSERT(msp->ms_freetree[t] == NULL);
msp->ms_alloctree[t] = range_tree_create(NULL, msp,
&msp->ms_lock);
- msp->ms_freetree[t] = range_tree_create(NULL, msp,
- &msp->ms_lock);
}
+ ASSERT3P(msp->ms_freeingtree, ==, NULL);
+ msp->ms_freeingtree = range_tree_create(NULL, msp,
+ &msp->ms_lock);
+
+ ASSERT3P(msp->ms_freedtree, ==, NULL);
+ msp->ms_freedtree = range_tree_create(NULL, msp,
+ &msp->ms_lock);
+
for (t = 0; t < TXG_DEFER_SIZE; t++) {
ASSERT(msp->ms_defertree[t] == NULL);
vdev_space_update(vd, 0, 0, msp->ms_size);
}
- freed_tree = &msp->ms_freetree[TXG_CLEAN(txg) & TXG_MASK];
defer_tree = &msp->ms_defertree[txg % TXG_DEFER_SIZE];
free_space = metaslab_class_get_space(spa_normal_class(spa)) -
defer_delta = 0;
alloc_delta = space_map_alloc_delta(msp->ms_sm);
if (defer_allowed) {
- defer_delta = range_tree_space(*freed_tree) -
+ defer_delta = range_tree_space(msp->ms_freedtree) -
range_tree_space(*defer_tree);
} else {
defer_delta -= range_tree_space(*defer_tree);
vdev_space_update(vd, alloc_delta + defer_delta, defer_delta, 0);
- ASSERT0(range_tree_space(msp->ms_alloctree[txg & TXG_MASK]));
- ASSERT0(range_tree_space(msp->ms_freetree[txg & TXG_MASK]));
-
/*
* If there's a metaslab_load() in progress, wait for it to complete
* so that we have a consistent view of the in-core space map.
range_tree_vacate(*defer_tree,
msp->ms_loaded ? range_tree_add : NULL, msp->ms_tree);
if (defer_allowed) {
- range_tree_swap(freed_tree, defer_tree);
+ range_tree_swap(&msp->ms_freedtree, defer_tree);
} else {
- range_tree_vacate(*freed_tree,
+ range_tree_vacate(msp->ms_freedtree,
msp->ms_loaded ? range_tree_add : NULL, msp->ms_tree);
}
range_tree_add(msp->ms_tree, offset, size);
msp->ms_max_size = metaslab_block_maxsize(msp);
} else {
- if (range_tree_space(msp->ms_freetree[txg & TXG_MASK]) == 0)
+ VERIFY3U(txg, ==, spa->spa_syncing_txg);
+ if (range_tree_space(msp->ms_freeingtree) == 0)
vdev_dirty(vd, VDD_METASLAB, msp, txg);
- range_tree_add(msp->ms_freetree[txg & TXG_MASK],
- offset, size);
+ range_tree_add(msp->ms_freeingtree, offset, size);
}
mutex_exit(&msp->ms_lock);
if (msp->ms_loaded)
range_tree_verify(msp->ms_tree, offset, size);
- for (j = 0; j < TXG_SIZE; j++)
- range_tree_verify(msp->ms_freetree[j], offset, size);
+ range_tree_verify(msp->ms_freeingtree, offset, size);
+ range_tree_verify(msp->ms_freedtree, offset, size);
for (j = 0; j < TXG_DEFER_SIZE; j++)
range_tree_verify(msp->ms_defertree[j], offset, size);
}
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