bcache: Add bch_btree_keys_u64s_remaining()

Helper function to explicitly check how much space is free in a btree node

Signed-off-by: Kent Overstreet <kmo@daterainc.com>

3 files changed, 31 insertions, 13 deletions

diff --git a/drivers/md/bcache/bset.h b/drivers/md/bcache/bset.h
index 87da828477f3..4fc40fd719de 100644
--- a/drivers/md/bcache/bset.h
+++ b/drivers/md/bcache/bset.h
@@ -260,6 +260,21 @@ static inline bool btree_keys_expensive_checks(struct btree_keys *b)
 #define set_blocks(i, block_bytes)                              \
         __set_blocks(i, (i)->keys, block_bytes)
 
+static inline size_t bch_btree_keys_u64s_remaining(struct btree_keys *b)
+{
+        struct bset_tree *t = bset_tree_last(b);
+
+        BUG_ON((PAGE_SIZE << b->page_order) <
+               (bset_byte_offset(b, t->data) + set_bytes(t->data)));
+
+        if (!b->last_set_unwritten)
+                return 0;
+
+        return ((PAGE_SIZE << b->page_order) -
+                (bset_byte_offset(b, t->data) + set_bytes(t->data))) /
+                sizeof(u64);
+}
+
 static inline struct bset *bset_next_set(struct btree_keys *b,
                                          unsigned block_bytes)
 {
diff --git a/drivers/md/bcache/btree.c b/drivers/md/bcache/btree.c
index 5d7dee8bb850..2c90003ff4ce 100644
--- a/drivers/md/bcache/btree.c
+++ b/drivers/md/bcache/btree.c
@@ -179,14 +179,6 @@ static inline struct bset *write_block(struct btree *b)
         return ((void *) btree_bset_first(b)) + b->written * block_bytes(b->c);
 }
 
-static inline bool should_split(struct btree *b)
-{
-        struct bset *i = write_block(b);
-        return b->written >= btree_blocks(b) ||
-                (b->written + __set_blocks(i, i->keys + 15, block_bytes(b->c))
-                 > btree_blocks(b));
-}
-
 /* Btree key manipulation */
 
 void bkey_put(struct cache_set *c, struct bkey *k)
@@ -2026,6 +2018,19 @@ merged:
         return true;
 }
 
+static size_t insert_u64s_remaining(struct btree *b)
+{
+        ssize_t ret = bch_btree_keys_u64s_remaining(&b->keys);
+
+        /*
+         * Might land in the middle of an existing extent and have to split it
+         */
+        if (b->keys.ops->is_extents)
+                ret -= KEY_MAX_U64S;
+
+        return max(ret, 0L);
+}
+
 static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
                                   struct keylist *insert_keys,
                                   struct bkey *replace_key)
@@ -2034,12 +2039,9 @@ static bool bch_btree_insert_keys(struct btree *b, struct btree_op *op,
         int oldsize = bch_count_data(b);
 
         while (!bch_keylist_empty(insert_keys)) {
-                struct bset *i = write_block(b);
                 struct bkey *k = insert_keys->keys;
 
-                if (b->written +
-                    __set_blocks(i, i->keys + bkey_u64s(k),
-                                 block_bytes(b->c)) > btree_blocks(b))
+                if (bkey_u64s(k) > insert_u64s_remaining(b))
                         break;
 
                 if (bkey_cmp(k, &b->key) <= 0) {
@@ -2203,7 +2205,7 @@ static int bch_btree_insert_node(struct btree *b, struct btree_op *op,
 {
         BUG_ON(b->level && replace_key);
 
-        if (should_split(b)) {
+        if (bch_keylist_nkeys(insert_keys) > insert_u64s_remaining(b)) {
                 if (current->bio_list) {
                         op->lock = b->c->root->level + 1;
                         return -EAGAIN;
diff --git a/include/uapi/linux/bcache.h b/include/uapi/linux/bcache.h
index ae66311be82f..22b6ad31c706 100644
--- a/include/uapi/linux/bcache.h
+++ b/include/uapi/linux/bcache.h
@@ -39,6 +39,7 @@ static inline void SET_##name(struct bkey *k, unsigned i, __u64 v)	\
 }
 
 #define KEY_SIZE_BITS           16
+#define KEY_MAX_U64S            8
 
 KEY_FIELD(KEY_PTRS,     high, 60, 3)
 KEY_FIELD(HEADER_SIZE,  high, 58, 2)