145 lines · c
1// SPDX-License-Identifier: GPL-2.02 3#include "bcachefs.h"4#include "bkey_methods.h"5#include "nocow_locking.h"6#include "util.h"7 8#include <linux/closure.h>9 10bool bch2_bucket_nocow_is_locked(struct bucket_nocow_lock_table *t, struct bpos bucket)11{12 u64 dev_bucket = bucket_to_u64(bucket);13 struct nocow_lock_bucket *l = bucket_nocow_lock(t, dev_bucket);14 unsigned i;15 16 for (i = 0; i < ARRAY_SIZE(l->b); i++)17 if (l->b[i] == dev_bucket && atomic_read(&l->l[i]))18 return true;19 return false;20}21 22#define sign(v) (v < 0 ? -1 : v > 0 ? 1 : 0)23 24void bch2_bucket_nocow_unlock(struct bucket_nocow_lock_table *t, struct bpos bucket, int flags)25{26 u64 dev_bucket = bucket_to_u64(bucket);27 struct nocow_lock_bucket *l = bucket_nocow_lock(t, dev_bucket);28 int lock_val = flags ? 1 : -1;29 unsigned i;30 31 for (i = 0; i < ARRAY_SIZE(l->b); i++)32 if (l->b[i] == dev_bucket) {33 int v = atomic_sub_return(lock_val, &l->l[i]);34 35 BUG_ON(v && sign(v) != lock_val);36 if (!v)37 closure_wake_up(&l->wait);38 return;39 }40 41 BUG();42}43 44bool __bch2_bucket_nocow_trylock(struct nocow_lock_bucket *l,45 u64 dev_bucket, int flags)46{47 int v, lock_val = flags ? 1 : -1;48 unsigned i;49 50 spin_lock(&l->lock);51 52 for (i = 0; i < ARRAY_SIZE(l->b); i++)53 if (l->b[i] == dev_bucket)54 goto got_entry;55 56 for (i = 0; i < ARRAY_SIZE(l->b); i++)57 if (!atomic_read(&l->l[i])) {58 l->b[i] = dev_bucket;59 goto take_lock;60 }61fail:62 spin_unlock(&l->lock);63 return false;64got_entry:65 v = atomic_read(&l->l[i]);66 if (lock_val > 0 ? v < 0 : v > 0)67 goto fail;68take_lock:69 v = atomic_read(&l->l[i]);70 /* Overflow? */71 if (v && sign(v + lock_val) != sign(v))72 goto fail;73 74 atomic_add(lock_val, &l->l[i]);75 spin_unlock(&l->lock);76 return true;77}78 79void __bch2_bucket_nocow_lock(struct bucket_nocow_lock_table *t,80 struct nocow_lock_bucket *l,81 u64 dev_bucket, int flags)82{83 if (!__bch2_bucket_nocow_trylock(l, dev_bucket, flags)) {84 struct bch_fs *c = container_of(t, struct bch_fs, nocow_locks);85 u64 start_time = local_clock();86 87 __closure_wait_event(&l->wait, __bch2_bucket_nocow_trylock(l, dev_bucket, flags));88 bch2_time_stats_update(&c->times[BCH_TIME_nocow_lock_contended], start_time);89 }90}91 92void bch2_nocow_locks_to_text(struct printbuf *out, struct bucket_nocow_lock_table *t)93 94{95 unsigned i, nr_zero = 0;96 struct nocow_lock_bucket *l;97 98 for (l = t->l; l < t->l + ARRAY_SIZE(t->l); l++) {99 unsigned v = 0;100 101 for (i = 0; i < ARRAY_SIZE(l->l); i++)102 v |= atomic_read(&l->l[i]);103 104 if (!v) {105 nr_zero++;106 continue;107 }108 109 if (nr_zero)110 prt_printf(out, "(%u empty entries)\n", nr_zero);111 nr_zero = 0;112 113 for (i = 0; i < ARRAY_SIZE(l->l); i++) {114 int v = atomic_read(&l->l[i]);115 if (v) {116 bch2_bpos_to_text(out, u64_to_bucket(l->b[i]));117 prt_printf(out, ": %s %u ", v < 0 ? "copy" : "update", abs(v));118 }119 }120 prt_newline(out);121 }122 123 if (nr_zero)124 prt_printf(out, "(%u empty entries)\n", nr_zero);125}126 127void bch2_fs_nocow_locking_exit(struct bch_fs *c)128{129 struct bucket_nocow_lock_table *t = &c->nocow_locks;130 131 for (struct nocow_lock_bucket *l = t->l; l < t->l + ARRAY_SIZE(t->l); l++)132 for (unsigned j = 0; j < ARRAY_SIZE(l->l); j++)133 BUG_ON(atomic_read(&l->l[j]));134}135 136int bch2_fs_nocow_locking_init(struct bch_fs *c)137{138 struct bucket_nocow_lock_table *t = &c->nocow_locks;139 140 for (struct nocow_lock_bucket *l = t->l; l < t->l + ARRAY_SIZE(t->l); l++)141 spin_lock_init(&l->lock);142 143 return 0;144}145