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124 lines
2.8 KiB
C
124 lines
2.8 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "bcachefs.h"
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#include "nocow_locking.h"
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#include "util.h"
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#include <linux/closure.h>
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bool bch2_bucket_nocow_is_locked(struct bucket_nocow_lock_table *t, struct bpos bucket)
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{
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u64 dev_bucket = bucket_to_u64(bucket);
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struct nocow_lock_bucket *l = bucket_nocow_lock(t, dev_bucket);
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unsigned i;
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for (i = 0; i < ARRAY_SIZE(l->b); i++)
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if (l->b[i] == dev_bucket && atomic_read(&l->l[i]))
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return true;
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return false;
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}
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#define sign(v) (v < 0 ? -1 : v > 0 ? 1 : 0)
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void bch2_bucket_nocow_unlock(struct bucket_nocow_lock_table *t, struct bpos bucket, int flags)
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{
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u64 dev_bucket = bucket_to_u64(bucket);
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struct nocow_lock_bucket *l = bucket_nocow_lock(t, dev_bucket);
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int lock_val = flags ? 1 : -1;
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unsigned i;
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for (i = 0; i < ARRAY_SIZE(l->b); i++)
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if (l->b[i] == dev_bucket) {
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BUG_ON(sign(atomic_read(&l->l[i])) != lock_val);
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if (!atomic_sub_return(lock_val, &l->l[i]))
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closure_wake_up(&l->wait);
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return;
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}
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BUG();
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}
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bool __bch2_bucket_nocow_trylock(struct nocow_lock_bucket *l,
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u64 dev_bucket, int flags)
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{
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int v, lock_val = flags ? 1 : -1;
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unsigned i;
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spin_lock(&l->lock);
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for (i = 0; i < ARRAY_SIZE(l->b); i++)
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if (l->b[i] == dev_bucket)
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goto got_entry;
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for (i = 0; i < ARRAY_SIZE(l->b); i++)
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if (!atomic_read(&l->l[i])) {
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l->b[i] = dev_bucket;
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goto take_lock;
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}
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fail:
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spin_unlock(&l->lock);
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return false;
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got_entry:
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v = atomic_read(&l->l[i]);
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if (lock_val > 0 ? v < 0 : v > 0)
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goto fail;
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take_lock:
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atomic_add(lock_val, &l->l[i]);
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spin_unlock(&l->lock);
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return true;
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}
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void __bch2_bucket_nocow_lock(struct bucket_nocow_lock_table *t,
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struct nocow_lock_bucket *l,
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u64 dev_bucket, int flags)
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{
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if (!__bch2_bucket_nocow_trylock(l, dev_bucket, flags)) {
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struct bch_fs *c = container_of(t, struct bch_fs, nocow_locks);
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u64 start_time = local_clock();
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__closure_wait_event(&l->wait, __bch2_bucket_nocow_trylock(l, dev_bucket, flags));
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bch2_time_stats_update(&c->times[BCH_TIME_nocow_lock_contended], start_time);
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}
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}
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void bch2_nocow_locks_to_text(struct printbuf *out, struct bucket_nocow_lock_table *t)
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{
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unsigned i, nr_zero = 0;
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struct nocow_lock_bucket *l;
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for (l = t->l; l < t->l + ARRAY_SIZE(t->l); l++) {
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unsigned v = 0;
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for (i = 0; i < ARRAY_SIZE(l->l); i++)
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v |= atomic_read(&l->l[i]);
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if (!v) {
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nr_zero++;
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continue;
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}
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if (nr_zero)
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prt_printf(out, "(%u empty entries)\n", nr_zero);
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nr_zero = 0;
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for (i = 0; i < ARRAY_SIZE(l->l); i++)
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if (atomic_read(&l->l[i]))
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prt_printf(out, "%llu: %i ", l->b[i], atomic_read(&l->l[i]));
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prt_newline(out);
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}
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if (nr_zero)
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prt_printf(out, "(%u empty entries)\n", nr_zero);
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}
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int bch2_fs_nocow_locking_init(struct bch_fs *c)
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{
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unsigned i;
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for (i = 0; i < ARRAY_SIZE(c->nocow_locks.l); i++)
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spin_lock_init(&c->nocow_locks.l[i].lock);
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return 0;
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}
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