1 files changed, 39 insertions, 6 deletions

diff --git a/fs/bcachefs/buckets.c b/fs/bcachefs/buckets.c
index d5ec4d727d0e..97151ec80c52 100644
--- a/fs/bcachefs/buckets.c
+++ b/fs/bcachefs/buckets.c
@@ -1176,8 +1176,10 @@ static int bch2_mark_reflink_p(struct bch_fs *c,
 	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);
 	struct reflink_gc *ref;
 	size_t l, r, m;
-	u64 idx = le64_to_cpu(p.v->idx);
-	unsigned sectors = p.k->size;
+	u64 idx = le64_to_cpu(p.v->idx) - le32_to_cpu(p.v->front_pad);
+	u64 sectors = (u64) le32_to_cpu(p.v->front_pad) +
+			    le32_to_cpu(p.v->back_pad) +
+			    p.k->size;
 	s64 ret = 0;
 
 	BUG_ON((flags & (BTREE_TRIGGER_INSERT|BTREE_TRIGGER_OVERWRITE)) ==
@@ -1753,12 +1755,33 @@ static int __bch2_trans_mark_reflink_p(struct btree_trans *trans,
 		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);
 		ret = -EIO;
 		goto err;
 	}
 
-	BUG_ON(!*refcount && (flags & BTREE_TRIGGER_OVERWRITE));
+	if (!*refcount && (flags & BTREE_TRIGGER_OVERWRITE)) {
+		bch2_fs_inconsistent(c,
+			"%llu:%llu len %u idx %llu indirect extent refcount underflow",
+			p.k->p.inode, p.k->p.offset, p.k->size, idx);
+		ret = -EIO;
+		goto err;
+	}
+
+	if (flags & BTREE_TRIGGER_INSERT) {
+		struct bch_reflink_p *v = (struct bch_reflink_p *) p.v;
+		u64 pad;
+
+		pad = max_t(s64, le32_to_cpu(v->front_pad),
+			    le64_to_cpu(v->idx) - bkey_start_offset(k.k));
+		BUG_ON(pad > U32_MAX);
+		v->front_pad = cpu_to_le32(pad);
+
+		pad = max_t(s64, le32_to_cpu(v->back_pad),
+			    k.k->p.offset - p.k->size - le64_to_cpu(v->idx));
+		BUG_ON(pad > U32_MAX);
+		v->back_pad = cpu_to_le32(pad);
+	}
+
 	le64_add_cpu(refcount, add);
 
 	if (!*refcount) {
@@ -1781,10 +1804,20 @@ static int bch2_trans_mark_reflink_p(struct btree_trans *trans,
 				     struct bkey_s_c k, unsigned flags)
 {
 	struct bkey_s_c_reflink_p p = bkey_s_c_to_reflink_p(k);
-	u64 idx = le64_to_cpu(p.v->idx);
-	unsigned sectors = p.k->size;
+	u64 idx, sectors;
 	s64 ret = 0;
 
+	if (flags & BTREE_TRIGGER_INSERT) {
+		struct bch_reflink_p *v = (struct bch_reflink_p *) p.v;
+
+		v->front_pad = v->back_pad = 0;
+	}
+
+	idx = le64_to_cpu(p.v->idx) - le32_to_cpu(p.v->front_pad);
+	sectors = (u64) le32_to_cpu(p.v->front_pad) +
+			le32_to_cpu(p.v->back_pad) +
+			p.k->size;
+
 	while (sectors) {
 		ret = __bch2_trans_mark_reflink_p(trans, p, idx, flags);
 		if (ret < 0)