From ce6ef5abe68251cb60c4585df2cc73e218ec0dba Mon Sep 17 00:00:00 2001 From: David Sterba Date: Mon, 8 Jun 2020 16:06:07 +0200 Subject: [PATCH] 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 Reviewed-by: Nikolay Borisov Signed-off-by: David Sterba --- fs/btrfs/ctree.c | 17 +++++++++++++++++ fs/btrfs/ctree.h | 48 ++++++++++++++++++++++++++++++++++++++++++++++++ 2 files changed, 65 insertions(+) diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c index 82ab6e5a386d..70e49d8d4f6c 100644 --- a/fs/btrfs/ctree.c +++ b/fs/btrfs/ctree.c @@ -1501,6 +1501,22 @@ static int close_blocks(u64 blocknr, u64 other, u32 blocksize) return 0; } +#ifdef __LITTLE_ENDIAN + +/* + * Compare two keys, on little-endian the disk order is same as CPU order and + * we can avoid the conversion. + */ +static int comp_keys(const struct btrfs_disk_key *disk_key, + const struct btrfs_key *k2) +{ + const struct btrfs_key *k1 = (const struct btrfs_key *)disk_key; + + return btrfs_comp_cpu_keys(k1, k2); +} + +#else + /* * compare two keys in a memcmp fashion */ @@ -1513,6 +1529,7 @@ static int comp_keys(const struct btrfs_disk_key *disk, return btrfs_comp_cpu_keys(&k1, k2); } +#endif /* * same as comp_keys only with two btrfs_key's diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h index 91a6c2b34c60..9138c40be755 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,