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f5241e4127
Factor out the debug code for rw filesystem refs into a small library. In release mode an enumerated ref is a normal percpu refcount, but in debug mode all enumerated users of the ref get their own atomic_long_t ref - making it much easier to chase down refcount usage bugs for when a refcount has many users. For debugging, we have enumerated_ref_to_text(), which prints the current value of each different user. Additionally, in debug mode enumerated_ref_stop() has a 10 second timeout, after which it will dump outstanding refcounts. Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
144 lines
3.1 KiB
C
144 lines
3.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#include "bcachefs.h"
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#include "enumerated_ref.h"
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#include "util.h"
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#include <linux/completion.h>
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#ifdef ENUMERATED_REF_DEBUG
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void enumerated_ref_get(struct enumerated_ref *ref, unsigned idx)
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{
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BUG_ON(idx >= ref->nr);
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atomic_long_inc(&ref->refs[idx]);
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}
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bool __enumerated_ref_tryget(struct enumerated_ref *ref, unsigned idx)
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{
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BUG_ON(idx >= ref->nr);
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return atomic_long_inc_not_zero(&ref->refs[idx]);
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}
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bool enumerated_ref_tryget(struct enumerated_ref *ref, unsigned idx)
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{
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BUG_ON(idx >= ref->nr);
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return !ref->dying &&
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atomic_long_inc_not_zero(&ref->refs[idx]);
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}
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void enumerated_ref_put(struct enumerated_ref *ref, unsigned idx)
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{
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BUG_ON(idx >= ref->nr);
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long v = atomic_long_dec_return(&ref->refs[idx]);
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BUG_ON(v < 0);
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if (v)
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return;
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for (unsigned i = 0; i < ref->nr; i++)
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if (atomic_long_read(&ref->refs[i]))
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return;
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if (ref->stop_fn)
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ref->stop_fn(ref);
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complete(&ref->stop_complete);
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}
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#endif
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#ifndef ENUMERATED_REF_DEBUG
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static void enumerated_ref_kill_cb(struct percpu_ref *percpu_ref)
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{
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struct enumerated_ref *ref =
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container_of(percpu_ref, struct enumerated_ref, ref);
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if (ref->stop_fn)
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ref->stop_fn(ref);
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complete(&ref->stop_complete);
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}
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#endif
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void enumerated_ref_stop_async(struct enumerated_ref *ref)
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{
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reinit_completion(&ref->stop_complete);
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#ifndef ENUMERATED_REF_DEBUG
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percpu_ref_kill(&ref->ref);
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#else
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ref->dying = true;
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for (unsigned i = 0; i < ref->nr; i++)
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enumerated_ref_put(ref, i);
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#endif
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}
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void enumerated_ref_stop(struct enumerated_ref *ref,
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const char * const names[])
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{
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enumerated_ref_stop_async(ref);
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while (!wait_for_completion_timeout(&ref->stop_complete, HZ * 10)) {
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struct printbuf buf = PRINTBUF;
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prt_str(&buf, "Waited for 10 seconds to shutdown enumerated ref\n");
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prt_str(&buf, "Outstanding refs:\n");
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enumerated_ref_to_text(&buf, ref, names);
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printk(KERN_ERR "%s", buf.buf);
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printbuf_exit(&buf);
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}
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}
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void enumerated_ref_start(struct enumerated_ref *ref)
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{
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#ifndef ENUMERATED_REF_DEBUG
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percpu_ref_reinit(&ref->ref);
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#else
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ref->dying = false;
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for (unsigned i = 0; i < ref->nr; i++) {
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BUG_ON(atomic_long_read(&ref->refs[i]));
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atomic_long_inc(&ref->refs[i]);
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}
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#endif
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}
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void enumerated_ref_exit(struct enumerated_ref *ref)
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{
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#ifndef ENUMERATED_REF_DEBUG
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percpu_ref_exit(&ref->ref);
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#else
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kfree(ref->refs);
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ref->refs = NULL;
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ref->nr = 0;
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#endif
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}
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int enumerated_ref_init(struct enumerated_ref *ref, unsigned nr,
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void (*stop_fn)(struct enumerated_ref *))
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{
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init_completion(&ref->stop_complete);
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ref->stop_fn = stop_fn;
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#ifndef ENUMERATED_REF_DEBUG
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return percpu_ref_init(&ref->ref, enumerated_ref_kill_cb,
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PERCPU_REF_INIT_DEAD, GFP_KERNEL);
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#else
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ref->refs = kzalloc(sizeof(ref->refs[0]) * nr, GFP_KERNEL);
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if (!ref->refs)
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return -ENOMEM;
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ref->nr = nr;
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return 0;
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#endif
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}
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void enumerated_ref_to_text(struct printbuf *out,
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struct enumerated_ref *ref,
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const char * const names[])
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{
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#ifdef ENUMERATED_REF_DEBUG
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bch2_printbuf_tabstop_push(out, 32);
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for (unsigned i = 0; i < ref->nr; i++)
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prt_printf(out, "%s\t%li\n", names[i],
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atomic_long_read(&ref->refs[i]));
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#else
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prt_str(out, "(not in debug mode)\n");
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#endif
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}
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