btrfs: add little-endian optimized key helpers
The CPU and on-disk keys are mapped to two different structures because
of the endianness. There's an intermediate buffer used to do the
conversion, but this is not necessary when CPU and on-disk endianness
match.
Add optimized versions of helpers that take disk_key and use the buffer
directly for CPU keys or drop the intermediate buffer and conversion.
This saves a lot of stack space accross many functions and removes about
6K of generated binary code:
text data bss dec hex filename
1090439 17468 14912 1122819 112203 pre/btrfs.ko
1084613 17456 14912 1116981 110b35 post/btrfs.ko
Delta: -5826
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 91a6c2b..9138c40 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -1895,6 +1895,52 @@ BTRFS_SETGET_STACK_FUNCS(disk_key_objectid, struct btrfs_disk_key,
BTRFS_SETGET_STACK_FUNCS(disk_key_offset, struct btrfs_disk_key, offset, 64);
BTRFS_SETGET_STACK_FUNCS(disk_key_type, struct btrfs_disk_key, type, 8);
+#ifdef __LITTLE_ENDIAN
+
+/*
+ * Optimized helpers for little-endian architectures where CPU and on-disk
+ * structures have the same endianness and we can skip conversions.
+ */
+
+static inline void btrfs_disk_key_to_cpu(struct btrfs_key *cpu_key,
+ const struct btrfs_disk_key *disk_key)
+{
+ memcpy(cpu_key, disk_key, sizeof(struct btrfs_key));
+}
+
+static inline void btrfs_cpu_key_to_disk(struct btrfs_disk_key *disk_key,
+ const struct btrfs_key *cpu_key)
+{
+ memcpy(disk_key, cpu_key, sizeof(struct btrfs_key));
+}
+
+static inline void btrfs_node_key_to_cpu(const struct extent_buffer *eb,
+ struct btrfs_key *cpu_key, int nr)
+{
+ struct btrfs_disk_key *disk_key = (struct btrfs_disk_key *)cpu_key;
+
+ btrfs_node_key(eb, disk_key, nr);
+}
+
+static inline void btrfs_item_key_to_cpu(const struct extent_buffer *eb,
+ struct btrfs_key *cpu_key, int nr)
+{
+ struct btrfs_disk_key *disk_key = (struct btrfs_disk_key *)cpu_key;
+
+ btrfs_item_key(eb, disk_key, nr);
+}
+
+static inline void btrfs_dir_item_key_to_cpu(const struct extent_buffer *eb,
+ const struct btrfs_dir_item *item,
+ struct btrfs_key *cpu_key)
+{
+ struct btrfs_disk_key *disk_key = (struct btrfs_disk_key *)cpu_key;
+
+ btrfs_dir_item_key(eb, item, disk_key);
+}
+
+#else
+
static inline void btrfs_disk_key_to_cpu(struct btrfs_key *cpu,
const struct btrfs_disk_key *disk)
{
@@ -1936,6 +1982,8 @@ static inline void btrfs_dir_item_key_to_cpu(const struct extent_buffer *eb,
btrfs_disk_key_to_cpu(key, &disk_key);
}
+#endif
+
/* struct btrfs_header */
BTRFS_SETGET_HEADER_FUNCS(header_bytenr, struct btrfs_header, bytenr, 64);
BTRFS_SETGET_HEADER_FUNCS(header_generation, struct btrfs_header,