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btrfs: struct-funcs, constify readers
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We have reader helpers for most of the on-disk structures that use
an extent_buffer and pointer as offset into the buffer that are
read-only.  We should mark them as const and, in turn, allow consumers
of these interfaces to mark the buffers const as well.

No impact on code, but serves as documentation that a buffer is intended
not to be modified.

Signed-off-by: Jeff Mahoney <jeffm@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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Jeff Mahoney authored and David Sterba committed Aug 16, 2017
1 parent 23d1f73 commit 1cbb1f4
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Showing 4 changed files with 91 additions and 89 deletions.
128 changes: 66 additions & 62 deletions fs/btrfs/ctree.h
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Original file line number Diff line number Diff line change
Expand Up @@ -1434,7 +1434,7 @@ do { \
#define BTRFS_INODE_ROOT_ITEM_INIT (1 << 31)

struct btrfs_map_token {
struct extent_buffer *eb;
const struct extent_buffer *eb;
char *kaddr;
unsigned long offset;
};
Expand Down Expand Up @@ -1468,18 +1468,19 @@ static inline void btrfs_init_map_token (struct btrfs_map_token *token)
sizeof(((type *)0)->member)))

#define DECLARE_BTRFS_SETGET_BITS(bits) \
u##bits btrfs_get_token_##bits(struct extent_buffer *eb, void *ptr, \
unsigned long off, \
struct btrfs_map_token *token); \
void btrfs_set_token_##bits(struct extent_buffer *eb, void *ptr, \
u##bits btrfs_get_token_##bits(const struct extent_buffer *eb, \
const void *ptr, unsigned long off, \
struct btrfs_map_token *token); \
void btrfs_set_token_##bits(struct extent_buffer *eb, const void *ptr, \
unsigned long off, u##bits val, \
struct btrfs_map_token *token); \
static inline u##bits btrfs_get_##bits(struct extent_buffer *eb, void *ptr, \
static inline u##bits btrfs_get_##bits(const struct extent_buffer *eb, \
const void *ptr, \
unsigned long off) \
{ \
return btrfs_get_token_##bits(eb, ptr, off, NULL); \
} \
static inline void btrfs_set_##bits(struct extent_buffer *eb, void *ptr, \
static inline void btrfs_set_##bits(struct extent_buffer *eb, void *ptr,\
unsigned long off, u##bits val) \
{ \
btrfs_set_token_##bits(eb, ptr, off, val, NULL); \
Expand All @@ -1491,7 +1492,8 @@ DECLARE_BTRFS_SETGET_BITS(32)
DECLARE_BTRFS_SETGET_BITS(64)

#define BTRFS_SETGET_FUNCS(name, type, member, bits) \
static inline u##bits btrfs_##name(struct extent_buffer *eb, type *s) \
static inline u##bits btrfs_##name(const struct extent_buffer *eb, \
const type *s) \
{ \
BUILD_BUG_ON(sizeof(u##bits) != sizeof(((type *)0))->member); \
return btrfs_get_##bits(eb, s, offsetof(type, member)); \
Expand All @@ -1502,7 +1504,8 @@ static inline void btrfs_set_##name(struct extent_buffer *eb, type *s, \
BUILD_BUG_ON(sizeof(u##bits) != sizeof(((type *)0))->member); \
btrfs_set_##bits(eb, s, offsetof(type, member), val); \
} \
static inline u##bits btrfs_token_##name(struct extent_buffer *eb, type *s, \
static inline u##bits btrfs_token_##name(const struct extent_buffer *eb,\
const type *s, \
struct btrfs_map_token *token) \
{ \
BUILD_BUG_ON(sizeof(u##bits) != sizeof(((type *)0))->member); \
Expand All @@ -1517,9 +1520,9 @@ static inline void btrfs_set_token_##name(struct extent_buffer *eb, \
}

#define BTRFS_SETGET_HEADER_FUNCS(name, type, member, bits) \
static inline u##bits btrfs_##name(struct extent_buffer *eb) \
static inline u##bits btrfs_##name(const struct extent_buffer *eb) \
{ \
type *p = page_address(eb->pages[0]); \
const type *p = page_address(eb->pages[0]); \
u##bits res = le##bits##_to_cpu(p->member); \
return res; \
} \
Expand All @@ -1531,7 +1534,7 @@ static inline void btrfs_set_##name(struct extent_buffer *eb, \
}

#define BTRFS_SETGET_STACK_FUNCS(name, type, member, bits) \
static inline u##bits btrfs_##name(type *s) \
static inline u##bits btrfs_##name(const type *s) \
{ \
return le##bits##_to_cpu(s->member); \
} \
Expand Down Expand Up @@ -1856,7 +1859,7 @@ static inline unsigned long btrfs_node_key_ptr_offset(int nr)
sizeof(struct btrfs_key_ptr) * nr;
}

void btrfs_node_key(struct extent_buffer *eb,
void btrfs_node_key(const struct extent_buffer *eb,
struct btrfs_disk_key *disk_key, int nr);

static inline void btrfs_set_node_key(struct extent_buffer *eb,
Expand Down Expand Up @@ -1885,28 +1888,28 @@ static inline struct btrfs_item *btrfs_item_nr(int nr)
return (struct btrfs_item *)btrfs_item_nr_offset(nr);
}

static inline u32 btrfs_item_end(struct extent_buffer *eb,
static inline u32 btrfs_item_end(const struct extent_buffer *eb,
struct btrfs_item *item)
{
return btrfs_item_offset(eb, item) + btrfs_item_size(eb, item);
}

static inline u32 btrfs_item_end_nr(struct extent_buffer *eb, int nr)
static inline u32 btrfs_item_end_nr(const struct extent_buffer *eb, int nr)
{
return btrfs_item_end(eb, btrfs_item_nr(nr));
}

static inline u32 btrfs_item_offset_nr(struct extent_buffer *eb, int nr)
static inline u32 btrfs_item_offset_nr(const struct extent_buffer *eb, int nr)
{
return btrfs_item_offset(eb, btrfs_item_nr(nr));
}

static inline u32 btrfs_item_size_nr(struct extent_buffer *eb, int nr)
static inline u32 btrfs_item_size_nr(const struct extent_buffer *eb, int nr)
{
return btrfs_item_size(eb, btrfs_item_nr(nr));
}

static inline void btrfs_item_key(struct extent_buffer *eb,
static inline void btrfs_item_key(const struct extent_buffer *eb,
struct btrfs_disk_key *disk_key, int nr)
{
struct btrfs_item *item = btrfs_item_nr(nr);
Expand Down Expand Up @@ -1942,16 +1945,16 @@ BTRFS_SETGET_STACK_FUNCS(stack_dir_name_len, struct btrfs_dir_item,
BTRFS_SETGET_STACK_FUNCS(stack_dir_transid, struct btrfs_dir_item,
transid, 64);

static inline void btrfs_dir_item_key(struct extent_buffer *eb,
struct btrfs_dir_item *item,
static inline void btrfs_dir_item_key(const struct extent_buffer *eb,
const struct btrfs_dir_item *item,
struct btrfs_disk_key *key)
{
read_eb_member(eb, item, struct btrfs_dir_item, location, key);
}

static inline void btrfs_set_dir_item_key(struct extent_buffer *eb,
struct btrfs_dir_item *item,
struct btrfs_disk_key *key)
const struct btrfs_disk_key *key)
{
write_eb_member(eb, item, struct btrfs_dir_item, location, key);
}
Expand All @@ -1963,16 +1966,16 @@ BTRFS_SETGET_FUNCS(free_space_bitmaps, struct btrfs_free_space_header,
BTRFS_SETGET_FUNCS(free_space_generation, struct btrfs_free_space_header,
generation, 64);

static inline void btrfs_free_space_key(struct extent_buffer *eb,
struct btrfs_free_space_header *h,
static inline void btrfs_free_space_key(const struct extent_buffer *eb,
const struct btrfs_free_space_header *h,
struct btrfs_disk_key *key)
{
read_eb_member(eb, h, struct btrfs_free_space_header, location, key);
}

static inline void btrfs_set_free_space_key(struct extent_buffer *eb,
struct btrfs_free_space_header *h,
struct btrfs_disk_key *key)
const struct btrfs_disk_key *key)
{
write_eb_member(eb, h, struct btrfs_free_space_header, location, key);
}
Expand All @@ -1999,25 +2002,25 @@ static inline void btrfs_cpu_key_to_disk(struct btrfs_disk_key *disk,
disk->objectid = cpu_to_le64(cpu->objectid);
}

static inline void btrfs_node_key_to_cpu(struct extent_buffer *eb,
struct btrfs_key *key, int nr)
static inline void btrfs_node_key_to_cpu(const struct extent_buffer *eb,
struct btrfs_key *key, int nr)
{
struct btrfs_disk_key disk_key;
btrfs_node_key(eb, &disk_key, nr);
btrfs_disk_key_to_cpu(key, &disk_key);
}

static inline void btrfs_item_key_to_cpu(struct extent_buffer *eb,
struct btrfs_key *key, int nr)
static inline void btrfs_item_key_to_cpu(const struct extent_buffer *eb,
struct btrfs_key *key, int nr)
{
struct btrfs_disk_key disk_key;
btrfs_item_key(eb, &disk_key, nr);
btrfs_disk_key_to_cpu(key, &disk_key);
}

static inline void btrfs_dir_item_key_to_cpu(struct extent_buffer *eb,
struct btrfs_dir_item *item,
struct btrfs_key *key)
static inline void btrfs_dir_item_key_to_cpu(const struct extent_buffer *eb,
const struct btrfs_dir_item *item,
struct btrfs_key *key)
{
struct btrfs_disk_key disk_key;
btrfs_dir_item_key(eb, item, &disk_key);
Expand Down Expand Up @@ -2049,7 +2052,7 @@ BTRFS_SETGET_STACK_FUNCS(stack_header_nritems, struct btrfs_header,
nritems, 32);
BTRFS_SETGET_STACK_FUNCS(stack_header_bytenr, struct btrfs_header, bytenr, 64);

static inline int btrfs_header_flag(struct extent_buffer *eb, u64 flag)
static inline int btrfs_header_flag(const struct extent_buffer *eb, u64 flag)
{
return (btrfs_header_flags(eb) & flag) == flag;
}
Expand All @@ -2068,7 +2071,7 @@ static inline int btrfs_clear_header_flag(struct extent_buffer *eb, u64 flag)
return (flags & flag) == flag;
}

static inline int btrfs_header_backref_rev(struct extent_buffer *eb)
static inline int btrfs_header_backref_rev(const struct extent_buffer *eb)
{
u64 flags = btrfs_header_flags(eb);
return flags >> BTRFS_BACKREF_REV_SHIFT;
Expand All @@ -2088,12 +2091,12 @@ static inline unsigned long btrfs_header_fsid(void)
return offsetof(struct btrfs_header, fsid);
}

static inline unsigned long btrfs_header_chunk_tree_uuid(struct extent_buffer *eb)
static inline unsigned long btrfs_header_chunk_tree_uuid(const struct extent_buffer *eb)
{
return offsetof(struct btrfs_header, chunk_tree_uuid);
}

static inline int btrfs_is_leaf(struct extent_buffer *eb)
static inline int btrfs_is_leaf(const struct extent_buffer *eb)
{
return btrfs_header_level(eb) == 0;
}
Expand Down Expand Up @@ -2127,12 +2130,12 @@ BTRFS_SETGET_STACK_FUNCS(root_stransid, struct btrfs_root_item,
BTRFS_SETGET_STACK_FUNCS(root_rtransid, struct btrfs_root_item,
rtransid, 64);

static inline bool btrfs_root_readonly(struct btrfs_root *root)
static inline bool btrfs_root_readonly(const struct btrfs_root *root)
{
return (root->root_item.flags & cpu_to_le64(BTRFS_ROOT_SUBVOL_RDONLY)) != 0;
}

static inline bool btrfs_root_dead(struct btrfs_root *root)
static inline bool btrfs_root_dead(const struct btrfs_root *root)
{
return (root->root_item.flags & cpu_to_le64(BTRFS_ROOT_SUBVOL_DEAD)) != 0;
}
Expand Down Expand Up @@ -2189,51 +2192,51 @@ BTRFS_SETGET_STACK_FUNCS(backup_num_devices, struct btrfs_root_backup,
/* struct btrfs_balance_item */
BTRFS_SETGET_FUNCS(balance_flags, struct btrfs_balance_item, flags, 64);

static inline void btrfs_balance_data(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
static inline void btrfs_balance_data(const struct extent_buffer *eb,
const struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
read_eb_member(eb, bi, struct btrfs_balance_item, data, ba);
}

static inline void btrfs_set_balance_data(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
struct btrfs_balance_item *bi,
const struct btrfs_disk_balance_args *ba)
{
write_eb_member(eb, bi, struct btrfs_balance_item, data, ba);
}

static inline void btrfs_balance_meta(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
static inline void btrfs_balance_meta(const struct extent_buffer *eb,
const struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
read_eb_member(eb, bi, struct btrfs_balance_item, meta, ba);
}

static inline void btrfs_set_balance_meta(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
struct btrfs_balance_item *bi,
const struct btrfs_disk_balance_args *ba)
{
write_eb_member(eb, bi, struct btrfs_balance_item, meta, ba);
}

static inline void btrfs_balance_sys(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
static inline void btrfs_balance_sys(const struct extent_buffer *eb,
const struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
{
read_eb_member(eb, bi, struct btrfs_balance_item, sys, ba);
}

static inline void btrfs_set_balance_sys(struct extent_buffer *eb,
struct btrfs_balance_item *bi,
struct btrfs_disk_balance_args *ba)
struct btrfs_balance_item *bi,
const struct btrfs_disk_balance_args *ba)
{
write_eb_member(eb, bi, struct btrfs_balance_item, sys, ba);
}

static inline void
btrfs_disk_balance_args_to_cpu(struct btrfs_balance_args *cpu,
struct btrfs_disk_balance_args *disk)
const struct btrfs_disk_balance_args *disk)
{
memset(cpu, 0, sizeof(*cpu));

Expand All @@ -2253,7 +2256,7 @@ btrfs_disk_balance_args_to_cpu(struct btrfs_balance_args *cpu,

static inline void
btrfs_cpu_balance_args_to_disk(struct btrfs_disk_balance_args *disk,
struct btrfs_balance_args *cpu)
const struct btrfs_balance_args *cpu)
{
memset(disk, 0, sizeof(*disk));

Expand Down Expand Up @@ -2321,7 +2324,7 @@ BTRFS_SETGET_STACK_FUNCS(super_magic, struct btrfs_super_block, magic, 64);
BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
uuid_tree_generation, 64);

static inline int btrfs_super_csum_size(struct btrfs_super_block *s)
static inline int btrfs_super_csum_size(const struct btrfs_super_block *s)
{
u16 t = btrfs_super_csum_type(s);
/*
Expand All @@ -2336,8 +2339,8 @@ static inline int btrfs_super_csum_size(struct btrfs_super_block *s)
* this returns the address of the start of the last item,
* which is the stop of the leaf data stack
*/
static inline unsigned int leaf_data_end(struct btrfs_fs_info *fs_info,
struct extent_buffer *leaf)
static inline unsigned int leaf_data_end(const struct btrfs_fs_info *fs_info,
const struct extent_buffer *leaf)
{
u32 nr = btrfs_header_nritems(leaf);

Expand All @@ -2362,7 +2365,7 @@ BTRFS_SETGET_STACK_FUNCS(stack_file_extent_compression,
struct btrfs_file_extent_item, compression, 8);

static inline unsigned long
btrfs_file_extent_inline_start(struct btrfs_file_extent_item *e)
btrfs_file_extent_inline_start(const struct btrfs_file_extent_item *e)
{
return (unsigned long)e + BTRFS_FILE_EXTENT_INLINE_DATA_START;
}
Expand Down Expand Up @@ -2396,18 +2399,19 @@ BTRFS_SETGET_FUNCS(file_extent_other_encoding, struct btrfs_file_extent_item,
* size of any extent headers. If a file is compressed on disk, this is
* the compressed size
*/
static inline u32 btrfs_file_extent_inline_item_len(struct extent_buffer *eb,
struct btrfs_item *e)
static inline u32 btrfs_file_extent_inline_item_len(
const struct extent_buffer *eb,
struct btrfs_item *e)
{
return btrfs_item_size(eb, e) - BTRFS_FILE_EXTENT_INLINE_DATA_START;
}

/* this returns the number of file bytes represented by the inline item.
* If an item is compressed, this is the uncompressed size
*/
static inline u32 btrfs_file_extent_inline_len(struct extent_buffer *eb,
int slot,
struct btrfs_file_extent_item *fi)
static inline u32 btrfs_file_extent_inline_len(const struct extent_buffer *eb,
int slot,
const struct btrfs_file_extent_item *fi)
{
struct btrfs_map_token token;

Expand All @@ -2429,8 +2433,8 @@ static inline u32 btrfs_file_extent_inline_len(struct extent_buffer *eb,


/* btrfs_dev_stats_item */
static inline u64 btrfs_dev_stats_value(struct extent_buffer *eb,
struct btrfs_dev_stats_item *ptr,
static inline u64 btrfs_dev_stats_value(const struct extent_buffer *eb,
const struct btrfs_dev_stats_item *ptr,
int index)
{
u64 val;
Expand Down
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