* [PATCH] bcachefs: Fix discard path journal flushing
@ 2025-01-29 20:48 Kent Overstreet
0 siblings, 0 replies; only message in thread
From: Kent Overstreet @ 2025-01-29 20:48 UTC (permalink / raw)
To: linux-bcachefs; +Cc: Kent Overstreet
The discard path is supposed to issue journal flushes when there's too
many buckets empty buckets that need a journal commit before they can be
written to again, but at some point this code seems to have been lost.
Bring it back with a new optimization to make sure we don't issue too
many journal flushes: the journal now tracks the sequence number of the
most recent flush in progress, which the discard path uses when deciding
which buckets need a journal flush.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
---
fs/bcachefs/alloc_background.c | 48 ++++++++++++-----------
fs/bcachefs/alloc_foreground.c | 10 +++--
fs/bcachefs/alloc_types.h | 1 +
fs/bcachefs/buckets_waiting_for_journal.c | 12 +++---
fs/bcachefs/buckets_waiting_for_journal.h | 4 +-
fs/bcachefs/journal.c | 1 +
fs/bcachefs/journal_types.h | 1 +
fs/bcachefs/trace.h | 14 ++++++-
8 files changed, 56 insertions(+), 35 deletions(-)
diff --git a/fs/bcachefs/alloc_background.c b/fs/bcachefs/alloc_background.c
index fc2ef33b67b3..4103dae26239 100644
--- a/fs/bcachefs/alloc_background.c
+++ b/fs/bcachefs/alloc_background.c
@@ -1803,7 +1803,6 @@ struct discard_buckets_state {
u64 open;
u64 need_journal_commit;
u64 discarded;
- u64 need_journal_commit_this_dev;
};
static int bch2_discard_one_bucket(struct btree_trans *trans,
@@ -1827,11 +1826,11 @@ static int bch2_discard_one_bucket(struct btree_trans *trans,
goto out;
}
- if (bch2_bucket_needs_journal_commit(&c->buckets_waiting_for_journal,
- c->journal.flushed_seq_ondisk,
- pos.inode, pos.offset)) {
- s->need_journal_commit++;
- s->need_journal_commit_this_dev++;
+ u64 seq_ready = bch2_bucket_journal_seq_ready(&c->buckets_waiting_for_journal,
+ pos.inode, pos.offset);
+ if (seq_ready > c->journal.flushed_seq_ondisk) {
+ if (seq_ready > c->journal.flushing_seq)
+ s->need_journal_commit++;
goto out;
}
@@ -1865,23 +1864,24 @@ static int bch2_discard_one_bucket(struct btree_trans *trans,
discard_locked = true;
}
- if (!bkey_eq(*discard_pos_done, iter.pos) &&
- ca->mi.discard && !c->opts.nochanges) {
- /*
- * This works without any other locks because this is the only
- * thread that removes items from the need_discard tree
- */
- bch2_trans_unlock_long(trans);
- blkdev_issue_discard(ca->disk_sb.bdev,
- k.k->p.offset * ca->mi.bucket_size,
- ca->mi.bucket_size,
- GFP_KERNEL);
- *discard_pos_done = iter.pos;
+ if (!bkey_eq(*discard_pos_done, iter.pos)) {
s->discarded++;
+ *discard_pos_done = iter.pos;
- ret = bch2_trans_relock_notrace(trans);
- if (ret)
- goto out;
+ if (ca->mi.discard && !c->opts.nochanges) {
+ /*
+ * This works without any other locks because this is the only
+ * thread that removes items from the need_discard tree
+ */
+ bch2_trans_unlock_long(trans);
+ blkdev_issue_discard(ca->disk_sb.bdev,
+ k.k->p.offset * ca->mi.bucket_size,
+ ca->mi.bucket_size,
+ GFP_KERNEL);
+ ret = bch2_trans_relock_notrace(trans);
+ if (ret)
+ goto out;
+ }
}
SET_BCH_ALLOC_V4_NEED_DISCARD(&a->v, false);
@@ -1929,6 +1929,10 @@ static void bch2_do_discards_work(struct work_struct *work)
POS(ca->dev_idx, U64_MAX), 0, k,
bch2_discard_one_bucket(trans, ca, &iter, &discard_pos_done, &s, false)));
+ /* XXX ratelimit journal flushes */
+ if (s.need_journal_commit > dev_buckets_available(ca, BCH_WATERMARK_normal))
+ bch2_journal_flush_async(&c->journal, NULL);
+
trace_discard_buckets(c, s.seen, s.open, s.need_journal_commit, s.discarded,
bch2_err_str(ret));
@@ -2024,7 +2028,7 @@ static void bch2_do_discards_fast_work(struct work_struct *work)
break;
}
- trace_discard_buckets(c, s.seen, s.open, s.need_journal_commit, s.discarded, bch2_err_str(ret));
+ trace_discard_buckets_fast(c, s.seen, s.open, s.need_journal_commit, s.discarded, bch2_err_str(ret));
bch2_trans_put(trans);
percpu_ref_put(&ca->io_ref);
diff --git a/fs/bcachefs/alloc_foreground.c b/fs/bcachefs/alloc_foreground.c
index ecd14962ab01..1759c15a7745 100644
--- a/fs/bcachefs/alloc_foreground.c
+++ b/fs/bcachefs/alloc_foreground.c
@@ -188,8 +188,12 @@ static inline bool may_alloc_bucket(struct bch_fs *c,
return false;
}
- if (bch2_bucket_needs_journal_commit(&c->buckets_waiting_for_journal,
- c->journal.flushed_seq_ondisk, bucket.inode, bucket.offset)) {
+ u64 journal_seq_ready =
+ bch2_bucket_journal_seq_ready(&c->buckets_waiting_for_journal,
+ bucket.inode, bucket.offset);
+ if (journal_seq_ready > c->journal.flushed_seq_ondisk) {
+ if (journal_seq_ready > c->journal.flushing_seq)
+ s->need_journal_commit++;
s->skipped_need_journal_commit++;
return false;
}
@@ -553,7 +557,7 @@ static struct open_bucket *bch2_bucket_alloc_trans(struct btree_trans *trans,
? bch2_bucket_alloc_freelist(trans, ca, watermark, &s, cl)
: bch2_bucket_alloc_early(trans, ca, watermark, &s, cl);
- if (s.skipped_need_journal_commit * 2 > avail)
+ if (s.need_journal_commit * 2 > avail)
bch2_journal_flush_async(&c->journal, NULL);
if (!ob && s.btree_bitmap != BTREE_BITMAP_ANY) {
diff --git a/fs/bcachefs/alloc_types.h b/fs/bcachefs/alloc_types.h
index 9bbb28e90b93..4aa8ee026cb8 100644
--- a/fs/bcachefs/alloc_types.h
+++ b/fs/bcachefs/alloc_types.h
@@ -18,6 +18,7 @@ struct bucket_alloc_state {
u64 buckets_seen;
u64 skipped_open;
u64 skipped_need_journal_commit;
+ u64 need_journal_commit;
u64 skipped_nocow;
u64 skipped_nouse;
u64 skipped_mi_btree_bitmap;
diff --git a/fs/bcachefs/buckets_waiting_for_journal.c b/fs/bcachefs/buckets_waiting_for_journal.c
index f9fb150eda70..c8a488e6b7b8 100644
--- a/fs/bcachefs/buckets_waiting_for_journal.c
+++ b/fs/bcachefs/buckets_waiting_for_journal.c
@@ -22,23 +22,21 @@ static void bucket_table_init(struct buckets_waiting_for_journal_table *t, size_
memset(t->d, 0, sizeof(t->d[0]) << t->bits);
}
-bool bch2_bucket_needs_journal_commit(struct buckets_waiting_for_journal *b,
- u64 flushed_seq,
- unsigned dev, u64 bucket)
+u64 bch2_bucket_journal_seq_ready(struct buckets_waiting_for_journal *b,
+ unsigned dev, u64 bucket)
{
struct buckets_waiting_for_journal_table *t;
u64 dev_bucket = (u64) dev << 56 | bucket;
- bool ret = false;
- unsigned i;
+ u64 ret = 0;
mutex_lock(&b->lock);
t = b->t;
- for (i = 0; i < ARRAY_SIZE(t->hash_seeds); i++) {
+ for (unsigned i = 0; i < ARRAY_SIZE(t->hash_seeds); i++) {
struct bucket_hashed *h = bucket_hash(t, i, dev_bucket);
if (h->dev_bucket == dev_bucket) {
- ret = h->journal_seq > flushed_seq;
+ ret = h->journal_seq;
break;
}
}
diff --git a/fs/bcachefs/buckets_waiting_for_journal.h b/fs/bcachefs/buckets_waiting_for_journal.h
index d2ae19cbe18c..365619ca44c8 100644
--- a/fs/bcachefs/buckets_waiting_for_journal.h
+++ b/fs/bcachefs/buckets_waiting_for_journal.h
@@ -4,8 +4,8 @@
#include "buckets_waiting_for_journal_types.h"
-bool bch2_bucket_needs_journal_commit(struct buckets_waiting_for_journal *,
- u64, unsigned, u64);
+u64 bch2_bucket_journal_seq_ready(struct buckets_waiting_for_journal *,
+ unsigned, u64);
int bch2_set_bucket_needs_journal_commit(struct buckets_waiting_for_journal *,
u64, unsigned, u64, u64);
diff --git a/fs/bcachefs/journal.c b/fs/bcachefs/journal.c
index cb2c3722f674..ee5cb8f7b5a7 100644
--- a/fs/bcachefs/journal.c
+++ b/fs/bcachefs/journal.c
@@ -783,6 +783,7 @@ int bch2_journal_flush_seq_async(struct journal *j, u64 seq,
}
buf->must_flush = true;
+ j->flushing_seq = max(j->flushing_seq, seq);
if (parent && !closure_wait(&buf->wait, parent))
BUG();
diff --git a/fs/bcachefs/journal_types.h b/fs/bcachefs/journal_types.h
index 3ba433a48eb8..a198a81d7478 100644
--- a/fs/bcachefs/journal_types.h
+++ b/fs/bcachefs/journal_types.h
@@ -237,6 +237,7 @@ struct journal {
/* seq, last_seq from the most recent journal entry successfully written */
u64 seq_ondisk;
u64 flushed_seq_ondisk;
+ u64 flushing_seq;
u64 last_seq_ondisk;
u64 err_seq;
u64 last_empty_seq;
diff --git a/fs/bcachefs/trace.h b/fs/bcachefs/trace.h
index 56a5a7fbc0fd..c1b51009edf6 100644
--- a/fs/bcachefs/trace.h
+++ b/fs/bcachefs/trace.h
@@ -727,7 +727,7 @@ DEFINE_EVENT(fs_str, bucket_alloc_fail,
TP_ARGS(c, str)
);
-TRACE_EVENT(discard_buckets,
+DECLARE_EVENT_CLASS(discard_buckets_class,
TP_PROTO(struct bch_fs *c, u64 seen, u64 open,
u64 need_journal_commit, u64 discarded, const char *err),
TP_ARGS(c, seen, open, need_journal_commit, discarded, err),
@@ -759,6 +759,18 @@ TRACE_EVENT(discard_buckets,
__entry->err)
);
+DEFINE_EVENT(discard_buckets_class, discard_buckets,
+ TP_PROTO(struct bch_fs *c, u64 seen, u64 open,
+ u64 need_journal_commit, u64 discarded, const char *err),
+ TP_ARGS(c, seen, open, need_journal_commit, discarded, err)
+);
+
+DEFINE_EVENT(discard_buckets_class, discard_buckets_fast,
+ TP_PROTO(struct bch_fs *c, u64 seen, u64 open,
+ u64 need_journal_commit, u64 discarded, const char *err),
+ TP_ARGS(c, seen, open, need_journal_commit, discarded, err)
+);
+
TRACE_EVENT(bucket_invalidate,
TP_PROTO(struct bch_fs *c, unsigned dev, u64 bucket, u32 sectors),
TP_ARGS(c, dev, bucket, sectors),
--
2.45.2
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