bcachefs: Fsck for reflink refcounts

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>

fs/bcachefs/bcachefs.h

@@ -391,6 +391,14 @@ struct gc_pos {
 	unsigned		level;
 };
 
+struct reflink_gc {
+	u64		offset;
+	u32		size;
+	u32		refcount;
+};
+
+typedef GENRADIX(struct reflink_gc) reflink_gc_table;
+
 struct io_count {
 	u64			sectors[2][BCH_DATA_NR];
 };
@@ -806,6 +814,9 @@ mempool_t		bio_bounce_pages;
 
 	/* REFLINK */
 	u64			reflink_hint;
+	reflink_gc_table	reflink_gc_table;
+	size_t			reflink_gc_nr;
+	size_t			reflink_gc_idx;
 
 	/* VFS IO PATH - fs-io.c */
 	struct bio_set		writepage_bioset;

fs/bcachefs/btree_gc.c

@@ -23,6 +23,7 @@
 #include "keylist.h"
 #include "move.h"
 #include "recovery.h"
+#include "reflink.h"
 #include "replicas.h"
 #include "super-io.h"
 #include "trace.h"
@@ -1285,6 +1286,201 @@ static int bch2_gc_start(struct bch_fs *c,
 	return 0;
 }
 
+static int bch2_gc_reflink_done_initial_fn(struct bch_fs *c, struct bkey_s_c k)
+{
+	struct reflink_gc *r;
+	const __le64 *refcount = bkey_refcount_c(k);
+	char buf[200];
+	int ret = 0;
+
+	if (!refcount)
+		return 0;
+
+	r = genradix_ptr(&c->reflink_gc_table, c->reflink_gc_idx++);
+	if (!r)
+		return -ENOMEM;
+
+	if (!r ||
+	    r->offset != k.k->p.offset ||
+	    r->size != k.k->size) {
+		bch_err(c, "unexpected inconsistency walking reflink table at gc finish");
+		return -EINVAL;
+	}
+
+	if (fsck_err_on(r->refcount != le64_to_cpu(*refcount), c,
+			"reflink key has wrong refcount:\n"
+			"  %s\n"
+			"  should be %u",
+			(bch2_bkey_val_to_text(&PBUF(buf), c, k), buf),
+			r->refcount)) {
+		struct bkey_i *new;
+
+		new = kmalloc(bkey_bytes(k.k), GFP_KERNEL);
+		if (!new) {
+			ret = -ENOMEM;
+			goto fsck_err;
+		}
+
+		bkey_reassemble(new, k);
+
+		if (!r->refcount) {
+			new->k.type = KEY_TYPE_deleted;
+			new->k.size = 0;
+		} else {
+			*bkey_refcount(new) = cpu_to_le64(r->refcount);
+		}
+
+		ret = bch2_journal_key_insert(c, BTREE_ID_reflink, 0, new);
+		if (ret)
+			kfree(new);
+	}
+fsck_err:
+	return ret;
+}
+
+static int bch2_gc_reflink_done(struct bch_fs *c, bool initial,
+				bool metadata_only)
+{
+	struct btree_trans trans;
+	struct btree_iter *iter;
+	struct bkey_s_c k;
+	struct reflink_gc *r;
+	size_t idx = 0;
+	char buf[200];
+	int ret = 0;
+
+	if (metadata_only)
+		return 0;
+
+	if (initial) {
+		c->reflink_gc_idx = 0;
+
+		ret = bch2_btree_and_journal_walk(c, BTREE_ID_reflink,
+				bch2_gc_reflink_done_initial_fn);
+		goto out;
+	}
+
+	bch2_trans_init(&trans, c, 0, 0);
+
+	for_each_btree_key(&trans, iter, BTREE_ID_reflink, POS_MIN,
+			   BTREE_ITER_PREFETCH, k, ret) {
+		const __le64 *refcount = bkey_refcount_c(k);
+
+		if (!refcount)
+			continue;
+
+		r = genradix_ptr(&c->reflink_gc_table, idx);
+		if (!r ||
+		    r->offset != k.k->p.offset ||
+		    r->size != k.k->size) {
+			bch_err(c, "unexpected inconsistency walking reflink table at gc finish");
+			ret = -EINVAL;
+			break;
+		}
+
+		if (fsck_err_on(r->refcount != le64_to_cpu(*refcount), c,
+				"reflink key has wrong refcount:\n"
+				"  %s\n"
+				"  should be %u",
+				(bch2_bkey_val_to_text(&PBUF(buf), c, k), buf),
+				r->refcount)) {
+			struct bkey_i *new;
+
+			new = kmalloc(bkey_bytes(k.k), GFP_KERNEL);
+			if (!new) {
+				ret = -ENOMEM;
+				break;
+			}
+
+			bkey_reassemble(new, k);
+
+			if (!r->refcount)
+				new->k.type = KEY_TYPE_deleted;
+			else
+				*bkey_refcount(new) = cpu_to_le64(r->refcount);
+
+			ret = __bch2_trans_do(&trans, NULL, NULL, 0,
+					__bch2_btree_insert(&trans, BTREE_ID_reflink, new));
+			kfree(new);
+
+			if (ret)
+				break;
+		}
+	}
+fsck_err:
+	bch2_trans_iter_put(&trans, iter);
+	bch2_trans_exit(&trans);
+out:
+	genradix_free(&c->reflink_gc_table);
+	c->reflink_gc_nr = 0;
+	return ret;
+}
+
+static int bch2_gc_reflink_start_initial_fn(struct bch_fs *c, struct bkey_s_c k)
+{
+
+	struct reflink_gc *r;
+	const __le64 *refcount = bkey_refcount_c(k);
+
+	if (!refcount)
+		return 0;
+
+	r = genradix_ptr_alloc(&c->reflink_gc_table, c->reflink_gc_nr++,
+			       GFP_KERNEL);
+	if (!r)
+		return -ENOMEM;
+
+	r->offset	= k.k->p.offset;
+	r->size		= k.k->size;
+	r->refcount	= 0;
+	return 0;
+}
+
+static int bch2_gc_reflink_start(struct bch_fs *c, bool initial,
+				 bool metadata_only)
+{
+	struct btree_trans trans;
+	struct btree_iter *iter;
+	struct bkey_s_c k;
+	struct reflink_gc *r;
+	int ret;
+
+	if (metadata_only)
+		return 0;
+
+	genradix_free(&c->reflink_gc_table);
+	c->reflink_gc_nr = 0;
+
+	if (initial)
+		return bch2_btree_and_journal_walk(c, BTREE_ID_reflink,
+				bch2_gc_reflink_start_initial_fn);
+
+	bch2_trans_init(&trans, c, 0, 0);
+
+	for_each_btree_key(&trans, iter, BTREE_ID_reflink, POS_MIN,
+			   BTREE_ITER_PREFETCH, k, ret) {
+		const __le64 *refcount = bkey_refcount_c(k);
+
+		if (!refcount)
+			continue;
+
+		r = genradix_ptr_alloc(&c->reflink_gc_table, c->reflink_gc_nr++,
+				       GFP_KERNEL);
+		if (!r) {
+			ret = -ENOMEM;
+			break;
+		}
+
+		r->offset	= k.k->p.offset;
+		r->size		= k.k->size;
+		r->refcount	= 0;
+	}
+	bch2_trans_iter_put(&trans, iter);
+
+	bch2_trans_exit(&trans);
+	return 0;
+}
+
 /**
  * bch2_gc - walk _all_ references to buckets, and recompute them:
  *
@@ -1319,7 +1515,8 @@ int bch2_gc(struct bch_fs *c, bool initial, bool metadata_only)
 	closure_wait_event(&c->btree_interior_update_wait,
 			   !bch2_btree_interior_updates_nr_pending(c));
 again:
-	ret = bch2_gc_start(c, metadata_only);
+	ret   = bch2_gc_start(c, metadata_only) ?:
+		bch2_gc_reflink_start(c, initial, metadata_only);
 	if (ret)
 		goto out;
 
@@ -1381,7 +1578,8 @@ out:
 		bch2_journal_block(&c->journal);
 
 		percpu_down_write(&c->mark_lock);
-		ret = bch2_gc_done(c, initial, metadata_only);
+		ret   = bch2_gc_reflink_done(c, initial, metadata_only) ?:
+			bch2_gc_done(c, initial, metadata_only);
 
 		bch2_journal_unblock(&c->journal);
 	} else {

fs/bcachefs/buckets.c

@@ -14,6 +14,7 @@
 #include "ec.h"
 #include "error.h"
 #include "movinggc.h"
+#include "reflink.h"
 #include "replicas.h"
 #include "trace.h"
 
@@ -1076,6 +1077,124 @@ static int bch2_mark_stripe(struct bch_fs *c,
 	return 0;
 }
 
+static int __reflink_p_frag_references(struct bkey_s_c_reflink_p p,
+				       u64 p_start, u64 p_end,
+				       u64 v_start, u64 v_end)
+{
+	if (p_start == p_end)
+		return false;
+
+	p_start	+= le64_to_cpu(p.v->idx);
+	p_end	+= le64_to_cpu(p.v->idx);
+
+	if (p_end <= v_start)
+		return false;
+	if (p_start >= v_end)
+		return false;
+	return true;
+}
+
+static int reflink_p_frag_references(struct bkey_s_c_reflink_p p,
+				     u64 start, u64 end,
+				     struct bkey_s_c k)
+{
+	return __reflink_p_frag_references(p, start, end,
+					   bkey_start_offset(k.k),
+					   k.k->p.offset);
+}
+
+static int __bch2_mark_reflink_p(struct bch_fs *c,
+			struct bkey_s_c_reflink_p p,
+			u64 idx, unsigned sectors,
+			unsigned front_frag,
+			unsigned back_frag,
+			unsigned flags,
+			size_t *r_idx)
+{
+	struct reflink_gc *r;
+	int add = !(flags & BTREE_TRIGGER_OVERWRITE) ? 1 : -1;
+	int frags_referenced;
+
+	while (1) {
+		if (*r_idx >= c->reflink_gc_nr)
+			goto not_found;
+		r = genradix_ptr(&c->reflink_gc_table, *r_idx);
+		BUG_ON(!r);
+
+		if (r->offset > idx)
+			break;
+		(*r_idx)++;
+	}
+
+	frags_referenced =
+		__reflink_p_frag_references(p, 0, front_frag,
+					    r->offset - r->size, r->offset) +
+		__reflink_p_frag_references(p, back_frag, p.k->size,
+					    r->offset - r->size, r->offset);
+
+	if (frags_referenced == 2) {
+		BUG_ON(!(flags & BTREE_TRIGGER_OVERWRITE_SPLIT));
+		add = -add;
+	} else if (frags_referenced == 1) {
+		BUG_ON(!(flags & BTREE_TRIGGER_OVERWRITE));
+		add = 0;
+	}
+
+	BUG_ON((s64) r->refcount + add < 0);
+
+	r->refcount += add;
+	return min_t(u64, sectors, r->offset - idx);
+not_found:
+	bch2_fs_inconsistent(c,
+		"%llu:%llu len %u points to nonexistent indirect extent %llu",
+		p.k->p.inode, p.k->p.offset, p.k->size, idx);
+	bch2_inconsistent_error(c);
+	return -EIO;
+}
+
+static int bch2_mark_reflink_p(struct bch_fs *c,
+			       struct bkey_s_c_reflink_p p, unsigned offset,
+			       s64 sectors, unsigned flags)
+{
+	u64 idx = le64_to_cpu(p.v->idx) + offset;
+	struct reflink_gc *ref;
+	size_t l, r, m;
+	unsigned front_frag, back_frag;
+	s64 ret = 0;
+
+	if (sectors < 0)
+		sectors = -sectors;
+
+	BUG_ON(offset + sectors > p.k->size);
+
+	front_frag = offset;
+	back_frag = offset + sectors;
+
+	l = 0;
+	r = c->reflink_gc_nr;
+	while (l < r) {
+		m = l + (r - l) / 2;
+
+		ref = genradix_ptr(&c->reflink_gc_table, m);
+		if (ref->offset <= idx)
+			l = m + 1;
+		else
+			r = m;
+	}
+
+	while (sectors) {
+		ret = __bch2_mark_reflink_p(c, p, idx, sectors,
+				front_frag, back_frag, flags, &l);
+		if (ret < 0)
+			return ret;
+
+		idx	+= ret;
+		sectors	-= ret;
+	}
+
+	return 0;
+}
+
 static int bch2_mark_key_locked(struct bch_fs *c,
 		   struct bkey_s_c old,
 		   struct bkey_s_c new,
@@ -1131,6 +1250,10 @@ static int bch2_mark_key_locked(struct bch_fs *c,
 		fs_usage->persistent_reserved[replicas - 1]	+= sectors;
 		break;
 	}
+	case KEY_TYPE_reflink_p:
+		ret = bch2_mark_reflink_p(c, bkey_s_c_to_reflink_p(k),
+					  offset, sectors, flags);
+		break;
 	}
 
 	preempt_enable();
@@ -1693,35 +1816,6 @@ static int bch2_trans_mark_stripe(struct btree_trans *trans,
 	return ret;
 }
 
-static __le64 *bkey_refcount(struct bkey_i *k)
-{
-	switch (k->k.type) {
-	case KEY_TYPE_reflink_v:
-		return &bkey_i_to_reflink_v(k)->v.refcount;
-	case KEY_TYPE_indirect_inline_data:
-		return &bkey_i_to_indirect_inline_data(k)->v.refcount;
-	default:
-		return NULL;
-	}
-}
-
-static bool reflink_p_frag_references(struct bkey_s_c_reflink_p p,
-				      u64 start, u64 end,
-				      struct bkey_s_c k)
-{
-	if (start == end)
-		return false;
-
-	start	+= le64_to_cpu(p.v->idx);
-	end	+= le64_to_cpu(p.v->idx);
-
-	if (end <= bkey_start_offset(k.k))
-		return false;
-	if (start >= k.k->p.offset)
-		return false;
-	return true;
-}
-
 static int __bch2_trans_mark_reflink_p(struct btree_trans *trans,
 			struct bkey_s_c_reflink_p p,
 			u64 idx, unsigned sectors,

fs/bcachefs/reflink.c

@@ -151,7 +151,7 @@ static int bch2_make_extent_indirect(struct btree_trans *trans,
 
 	set_bkey_val_bytes(&r_v->k, sizeof(__le64) + bkey_val_bytes(&orig->k));
 
-	refcount	= (void *) &r_v->v;
+	refcount	= bkey_refcount(r_v);
 	*refcount	= 0;
 	memcpy(refcount + 1, &orig->v, bkey_val_bytes(&orig->k));
 

fs/bcachefs/reflink.h

@@ -34,6 +34,30 @@ void bch2_indirect_inline_data_to_text(struct printbuf *,
 	.val_to_text	= bch2_indirect_inline_data_to_text,	\
 }
 
+static inline const __le64 *bkey_refcount_c(struct bkey_s_c k)
+{
+	switch (k.k->type) {
+	case KEY_TYPE_reflink_v:
+		return &bkey_s_c_to_reflink_v(k).v->refcount;
+	case KEY_TYPE_indirect_inline_data:
+		return &bkey_s_c_to_indirect_inline_data(k).v->refcount;
+	default:
+		return NULL;
+	}
+}
+
+static inline __le64 *bkey_refcount(struct bkey_i *k)
+{
+	switch (k->k.type) {
+	case KEY_TYPE_reflink_v:
+		return &bkey_i_to_reflink_v(k)->v.refcount;
+	case KEY_TYPE_indirect_inline_data:
+		return &bkey_i_to_indirect_inline_data(k)->v.refcount;
+	default:
+		return NULL;
+	}
+}
+
 s64 bch2_remap_range(struct bch_fs *, struct bpos, struct bpos,
 		     u64, u64 *, u64, s64 *);