bcachefs: Invalidate buckets when writing to alloc btree

Prep work for persistent alloc information. Refactoring also lets us
make free_inc much smaller, which means a lot fewer buckets stranded on
freelists.
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/alloc.h

@@ -9,6 +9,8 @@ struct bch_dev;
 struct bch_fs;
 struct bch_devs_List;
 
+#define ALLOC_SCAN_BATCH(ca)		((ca)->mi.nbuckets >> 9)
+
 const char *bch2_alloc_invalid(const struct bch_fs *, struct bkey_s_c);
 void bch2_alloc_to_text(struct bch_fs *, char *, size_t, struct bkey_s_c);
 

fs/bcachefs/bcachefs.h

@@ -270,6 +270,10 @@ do {									\
 		"Store the journal sequence number in the version "	\
 		"number of every btree key, and verify that btree "	\
 		"update ordering is preserved during recovery")		\
+	BCH_DEBUG_PARAM(test_alloc_startup,				\
+		"Force allocator startup to use the slowpath where it"	\
+		"can't find enough free buckets without invalidating"	\
+		"cached data")
 
 #define BCH_DEBUG_PARAMS_ALL() BCH_DEBUG_PARAMS_ALWAYS() BCH_DEBUG_PARAMS_DEBUG()
 
@@ -403,7 +407,6 @@ struct bch_dev {
 	alloc_fifo		free[RESERVE_NR];
 	alloc_fifo		free_inc;
 	spinlock_t		freelist_lock;
-	size_t			nr_invalidated;
 
 	u8			open_buckets_partial[OPEN_BUCKETS_COUNT];
 	unsigned		open_buckets_partial_nr;
@@ -415,8 +418,6 @@ struct bch_dev {
 
 	size_t			inc_gen_needs_gc;
 	size_t			inc_gen_really_needs_gc;
-	u64			allocator_journal_seq_flush;
-	bool			allocator_invalidating_data;
 	bool			allocator_blocked;
 
 	alloc_heap		alloc_heap;

fs/bcachefs/btree_update_interior.c

@@ -1145,7 +1145,8 @@ static void bch2_btree_set_root(struct btree_update *as, struct btree *b,
 	struct btree *old;
 
 	trace_btree_set_root(c, b);
-	BUG_ON(!b->written);
+	BUG_ON(!b->written &&
+	       !test_bit(BCH_FS_HOLD_BTREE_WRITES, &c->flags));
 
 	old = btree_node_root(c, b);
 

fs/bcachefs/buckets.c

@@ -405,7 +405,7 @@ static void bch2_dev_usage_update(struct bch_fs *c, struct bch_dev *ca,
 	_old;							\
 })
 
-bool bch2_invalidate_bucket(struct bch_fs *c, struct bch_dev *ca,
+void bch2_invalidate_bucket(struct bch_fs *c, struct bch_dev *ca,
 			    size_t b, struct bucket_mark *old)
 {
 	struct bucket *g;
@@ -416,8 +416,7 @@ bool bch2_invalidate_bucket(struct bch_fs *c, struct bch_dev *ca,
 	g = bucket(ca, b);
 
 	*old = bucket_data_cmpxchg(c, ca, g, new, ({
-		if (!is_available_bucket(new))
-			return false;
+		BUG_ON(!is_available_bucket(new));
 
 		new.owned_by_allocator	= 1;
 		new.data_type		= 0;
@@ -429,7 +428,6 @@ bool bch2_invalidate_bucket(struct bch_fs *c, struct bch_dev *ca,
 	if (!old->owned_by_allocator && old->cached_sectors)
 		trace_invalidate(ca, bucket_to_sector(ca, b),
 				 old->cached_sectors);
-	return true;
 }
 
 void bch2_mark_alloc_bucket(struct bch_fs *c, struct bch_dev *ca,
@@ -822,7 +820,8 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 	/* XXX: these should be tunable */
 	size_t reserve_none	= max_t(size_t, 4, ca->mi.nbuckets >> 9);
 	size_t copygc_reserve	= max_t(size_t, 16, ca->mi.nbuckets >> 7);
-	size_t free_inc_reserve = copygc_reserve / 2;
+	size_t free_inc_nr	= max(max_t(size_t, 16, ca->mi.nbuckets >> 12),
+				      btree_reserve);
 	bool resize = ca->buckets != NULL,
 	     start_copygc = ca->copygc_thread != NULL;
 	int ret = -ENOMEM;
@@ -845,8 +844,8 @@ int bch2_dev_buckets_resize(struct bch_fs *c, struct bch_dev *ca, u64 nbuckets)
 	    !init_fifo(&free[RESERVE_MOVINGGC],
 		       copygc_reserve, GFP_KERNEL) ||
 	    !init_fifo(&free[RESERVE_NONE], reserve_none, GFP_KERNEL) ||
-	    !init_fifo(&free_inc,	free_inc_reserve, GFP_KERNEL) ||
-	    !init_heap(&alloc_heap,	free_inc_reserve, GFP_KERNEL) ||
+	    !init_fifo(&free_inc,	free_inc_nr, GFP_KERNEL) ||
+	    !init_heap(&alloc_heap,	ALLOC_SCAN_BATCH(ca) << 1, GFP_KERNEL) ||
 	    !init_heap(&copygc_heap,	copygc_reserve, GFP_KERNEL))
 		goto err;
 

fs/bcachefs/buckets.h

@@ -205,7 +205,7 @@ static inline bool bucket_needs_journal_commit(struct bucket_mark m,
 
 void bch2_bucket_seq_cleanup(struct bch_fs *);
 
-bool bch2_invalidate_bucket(struct bch_fs *, struct bch_dev *,
+void bch2_invalidate_bucket(struct bch_fs *, struct bch_dev *,
 			    size_t, struct bucket_mark *);
 void bch2_mark_alloc_bucket(struct bch_fs *, struct bch_dev *,
 			    size_t, bool, struct gc_pos, unsigned);