bcachefs: bch2_extent_trim_atomic()

Prep work for extents insert hook removal
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>

fs/bcachefs/extents.c

@@ -1298,6 +1298,17 @@ extent_insert_advance_pos(struct extent_insert_state *s, struct bkey_s_c k)
 	return __extent_insert_advance_pos(s, next_pos, k);
 }
 
+void bch2_extent_trim_atomic(struct bkey_i *k, struct btree_iter *iter)
+{
+	struct btree *b = iter->l[0].b;
+
+	BUG_ON(iter->uptodate > BTREE_ITER_NEED_PEEK);
+
+	bch2_cut_back(b->key.k.p, &k->k);
+
+	BUG_ON(bkey_cmp(bkey_start_pos(&k->k), b->data->min_key) < 0);
+}
+
 enum btree_insert_ret
 bch2_extent_can_insert(struct btree_insert *trans,
 		       struct btree_insert_entry *insert,
@@ -1311,6 +1322,9 @@ bch2_extent_can_insert(struct btree_insert *trans,
 	struct bkey_s_c k;
 	int sectors;
 
+	BUG_ON(trans->flags & BTREE_INSERT_ATOMIC &&
+	       !bch2_extent_is_atomic(&insert->k->k, insert->iter));
+
 	/*
 	 * We avoid creating whiteouts whenever possible when deleting, but
 	 * those optimizations mean we may potentially insert two whiteouts

fs/bcachefs/extents.h

@@ -62,6 +62,17 @@ int bch2_extent_pick_ptr(struct bch_fs *, struct bkey_s_c,
 			 struct bch_devs_mask *,
 			 struct extent_pick_ptr *);
 
+void bch2_extent_trim_atomic(struct bkey_i *, struct btree_iter *);
+
+static inline bool bch2_extent_is_atomic(struct bkey *k,
+					 struct btree_iter *iter)
+{
+	struct btree *b = iter->l[0].b;
+
+	return bkey_cmp(k->p, b->key.k.p) <= 0 &&
+		bkey_cmp(bkey_start_pos(k), b->data->min_key) >= 0;
+}
+
 enum btree_insert_ret
 bch2_extent_can_insert(struct btree_insert *, struct btree_insert_entry *,
 		       unsigned *);

fs/bcachefs/fs-io.c

@@ -6,6 +6,7 @@
 #include "buckets.h"
 #include "clock.h"
 #include "error.h"
+#include "extents.h"
 #include "fs.h"
 #include "fs-io.h"
 #include "fsck.h"
@@ -430,17 +431,22 @@ static int bchfs_write_index_update(struct bch_write_op *wop)
 	hook.need_inode_update	= false;
 
 	do {
-		/* XXX: inode->i_size locking */
-		k = bch2_keylist_front(keys);
-		if (min(k->k.p.offset << 9, op->new_i_size) >
-		    op->inode->ei_inode.bi_size)
-			hook.need_inode_update = true;
+		BKEY_PADDED(k) tmp;
 
-		/* optimization for fewer transaction restarts: */
 		ret = bch2_btree_iter_traverse(extent_iter);
 		if (ret)
 			goto err;
 
+		bkey_copy(&tmp.k, bch2_keylist_front(keys));
+		k = &tmp.k;
+
+		bch2_extent_trim_atomic(k, extent_iter);
+
+		/* XXX: inode->i_size locking */
+		if (min(k->k.p.offset << 9, op->new_i_size) >
+		    op->inode->ei_inode.bi_size)
+			hook.need_inode_update = true;
+
 		if (hook.need_inode_update) {
 			struct bkey_s_c inode;
 
@@ -515,8 +521,10 @@ static int bchfs_write_index_update(struct bch_write_op *wop)
 		if (hook.need_inode_update)
 			op->inode->ei_inode = hook.inode_u;
 
-		BUG_ON(bkey_cmp(extent_iter->pos, k->k.p) < 0);
-		bch2_keylist_pop_front(keys);
+		if (bkey_cmp(extent_iter->pos, bch2_keylist_front(keys)->k.p) < 0)
+			bch2_cut_front(extent_iter->pos, bch2_keylist_front(keys));
+		else
+			bch2_keylist_pop_front(keys);
 	} while (!bch2_keylist_empty(keys));
 
 	bch2_trans_exit(&trans);
@@ -2458,6 +2466,12 @@ static long bch2_fcollapse(struct bch_inode_info *inode,
 		bch2_cut_front(src->pos, &copy.k);
 		copy.k.k.p.offset -= len >> 9;
 
+		ret = bch2_btree_iter_traverse(dst);
+		if (ret)
+			goto btree_iter_err;
+
+		bch2_extent_trim_atomic(&copy.k, dst);
+
 		BUG_ON(bkey_cmp(dst->pos, bkey_start_pos(&copy.k.k)));
 
 		ret = bch2_disk_reservation_get(c, &disk_res, copy.k.k.size,