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bcachefs: Kill JOURNAL_NEED_WRITE

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This replaces the journal flag JOURNAL_NEED_WRITE with per-journal buf
state - more explicit, and solving a race in the old code that would
lead to entries being opened and written unnecessarily.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
This commit is contained in:
Kent Overstreet 2022-02-25 10:28:20 -05:00 committed by Kent Overstreet
parent 506bac7e59
commit fbec3b8800
3 changed files with 54 additions and 31 deletions
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63
fs/bcachefs/journal.c
View File

@ -86,6 +86,7 @@ static void bch2_journal_buf_init(struct journal *j)
buf->noflush = false;
buf->must_flush = false;
buf->separate_flush = false;
buf->flush_time = 0;
memset(buf->data, 0, sizeof(*buf->data));
buf->data->seq = cpu_to_le64(journal_cur_seq(j));
@ -152,11 +153,6 @@ static bool __journal_entry_close(struct journal *j)
return true;
}
if (!test_bit(JOURNAL_NEED_WRITE, &j->flags)) {
set_bit(JOURNAL_NEED_WRITE, &j->flags);
j->need_write_time = local_clock();
}
new.cur_entry_offset = JOURNAL_ENTRY_CLOSED_VAL;
new.idx++;
@ -205,7 +201,6 @@ static bool __journal_entry_close(struct journal *j)
bch2_journal_buf_init(j);
cancel_delayed_work(&j->write_work);
clear_bit(JOURNAL_NEED_WRITE, &j->flags);
bch2_journal_space_available(j);
@ -216,15 +211,16 @@ static bool __journal_entry_close(struct journal *j)
static bool journal_entry_want_write(struct journal *j)
{
union journal_res_state s = READ_ONCE(j->reservations);
struct journal_buf *buf = journal_cur_buf(j);
bool ret = false;
/*
* Don't close it yet if we already have a write in flight, but do set
* NEED_WRITE:
*/
if (s.idx != s.unwritten_idx)
set_bit(JOURNAL_NEED_WRITE, &j->flags);
else
if (!buf->flush_time) {
buf->flush_time = local_clock() ?: 1;
buf->expires = jiffies;
}
/* Don't close it yet if we already have a write in flight: */
if (s.idx == s.unwritten_idx)
ret = __journal_entry_close(j);
return ret;
@ -278,6 +274,8 @@ static int journal_entry_open(struct journal *j)
*/
BUG_ON(buf->data->u64s);
buf->expires = jiffies +
msecs_to_jiffies(c->opts.journal_flush_delay);
buf->u64s_reserved = j->entry_u64s_reserved;
buf->disk_sectors = j->cur_entry_sectors;
buf->sectors = min(buf->disk_sectors, buf->buf_size >> 9);
@ -337,8 +335,19 @@ static void journal_quiesce(struct journal *j)
static void journal_write_work(struct work_struct *work)
{
struct journal *j = container_of(work, struct journal, write_work.work);
struct bch_fs *c = container_of(j, struct bch_fs, journal);
struct journal_buf *buf;
long delta;
journal_entry_close(j);
spin_lock(&j->lock);
buf = journal_cur_buf(j);
delta = buf->expires - jiffies;
if (delta > 0)
mod_delayed_work(c->io_complete_wq, &j->write_work, delta);
else
__journal_entry_close(j);
spin_unlock(&j->lock);
}
static int __journal_res_get(struct journal *j, struct journal_res *res,
@ -591,7 +600,11 @@ recheck_need_open:
seq = res.seq;
buf = j->buf + (seq & JOURNAL_BUF_MASK);
buf->must_flush = true;
set_bit(JOURNAL_NEED_WRITE, &j->flags);
if (!buf->flush_time) {
buf->flush_time = local_clock() ?: 1;
buf->expires = jiffies;
}
if (parent && !closure_wait(&buf->wait, parent))
BUG();
@ -657,7 +670,11 @@ int bch2_journal_meta(struct journal *j)
buf = j->buf + (res.seq & JOURNAL_BUF_MASK);
buf->must_flush = true;
set_bit(JOURNAL_NEED_WRITE, &j->flags);
if (!buf->flush_time) {
buf->flush_time = local_clock() ?: 1;
buf->expires = jiffies;
}
bch2_journal_res_put(j, &res);
@ -1233,12 +1250,22 @@ void __bch2_journal_debug_to_text(struct printbuf *out, struct journal *j)
pr_buf(out, "unwritten entry:\tidx %u refcount %u sectors %u\n",
i, journal_state_count(s, i), j->buf[i].sectors);
pr_indent_push(out, 2);
pr_buf(out, "refcount %u", journal_state_count(s, i));
pr_newline(out);
pr_buf(out, "sectors %u", j->buf[i].sectors);
pr_newline(out);
pr_buf(out, "expires %li ms", jiffies_to_msecs(j->buf[i].expires - jiffies));
pr_newline(out);
pr_indent_pop(out, 2);
}
pr_buf(out,
"need write:\t\t%i\n"
"replay done:\t\t%i\n",
test_bit(JOURNAL_NEED_WRITE, &j->flags),
test_bit(JOURNAL_REPLAY_DONE, &j->flags));
pr_buf(out, "space:\n");

12
fs/bcachefs/journal_io.c
View File

@ -1403,13 +1403,15 @@ static void journal_write_done(struct closure *cl)
closure_wake_up(&w->wait);
journal_wake(j);
if (test_bit(JOURNAL_NEED_WRITE, &j->flags))
mod_delayed_work(c->io_complete_wq, &j->write_work, 0);
spin_unlock(&j->lock);
if (new.unwritten_idx == new.idx) {
struct journal_buf *buf = journal_cur_buf(j);
long delta = buf->expires - jiffies;
if (new.unwritten_idx != new.idx &&
!journal_state_count(new, new.unwritten_idx))
mod_delayed_work(c->io_complete_wq, &j->write_work, max(0L, delta));
} else if (!journal_state_count(new, new.unwritten_idx))
closure_call(&j->io, bch2_journal_write, c->io_complete_wq, NULL);
spin_unlock(&j->lock);
}
static void journal_write_endio(struct bio *bio)

10
fs/bcachefs/journal_types.h
View File

@ -25,6 +25,8 @@ struct journal_buf {
struct closure_waitlist wait;
u64 last_seq; /* copy of data->last_seq */
unsigned long expires;
u64 flush_time;
unsigned buf_size; /* size in bytes of @data */
unsigned sectors; /* maximum size for current entry */
@ -139,16 +141,9 @@ enum journal_space_from {
journal_space_nr,
};
/*
* JOURNAL_NEED_WRITE - current (pending) journal entry should be written ASAP,
* either because something's waiting on the write to complete or because it's
* been dirty too long and the timer's expired.
*/
enum {
JOURNAL_REPLAY_DONE,
JOURNAL_STARTED,
JOURNAL_NEED_WRITE,
JOURNAL_MAY_GET_UNRESERVED,
JOURNAL_MAY_SKIP_FLUSH,
};
@ -266,7 +261,6 @@ struct journal {
unsigned long last_flush_write;
u64 res_get_blocked_start;
u64 need_write_time;
u64 write_start_time;
u64 nr_flush_writes;