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btrfs: add little-endian optimized key helpers

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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>
This commit is contained in:
David Sterba 2020-06-08 16:06:07 +02:00
parent 5958253cf6
commit ce6ef5abe6
2 changed files with 65 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

17
fs/btrfs/ctree.c
View File

@ -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

48
fs/btrfs/ctree.h
View File

@ -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,