[PATCH 3.16 037/245] btrfs: struct-funcs, constify readers

Ben Hutchings
2020-04-23T23:06:56Z

From: Jeff Mahoney <jeffm@suse.com>

commit 1cbb1f454e5321e47fc1e6b233066c7ccc979d15 upstream.

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>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/ctree.h | 128 +++++++++++++++++++++-------------------
fs/btrfs/extent_io.c | 24 ++++----
fs/btrfs/extent_io.h | 19 +++---
fs/btrfs/struct-funcs.c | 9 +--
4 files changed, 91 insertions(+), 89 deletions(-)

--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2138,7 +2138,7 @@ struct btrfs_ioctl_defrag_range_args {
#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;
};
@@ -2169,18 +2169,19 @@ static inline void btrfs_init_map_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); \
@@ -2192,7 +2193,8 @@ 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)); \
@@ -2203,7 +2205,8 @@ static inline void btrfs_set_##name(stru
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); \
@@ -2218,9 +2221,9 @@ static inline void btrfs_set_token_##nam
}

#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; \
} \
@@ -2232,7 +2235,7 @@ static inline void btrfs_set_##name(stru
}

#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); \
} \
@@ -2558,7 +2561,7 @@ static inline unsigned long btrfs_node_k
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,
@@ -2587,28 +2590,28 @@ static inline struct btrfs_item *btrfs_i
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);
@@ -2644,8 +2647,8 @@ BTRFS_SETGET_STACK_FUNCS(stack_dir_name_
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);
@@ -2653,7 +2656,7 @@ static inline void btrfs_dir_item_key(st

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);
}
@@ -2665,8 +2668,8 @@ BTRFS_SETGET_FUNCS(free_space_bitmaps, s
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);
@@ -2674,7 +2677,7 @@ static inline void btrfs_free_space_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);
}
@@ -2701,25 +2704,25 @@ static inline void btrfs_cpu_key_to_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);
@@ -2752,7 +2755,7 @@ BTRFS_SETGET_STACK_FUNCS(stack_header_nr
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;
}
@@ -2771,7 +2774,7 @@ static inline int btrfs_clear_header_fla
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;
@@ -2791,12 +2794,12 @@ static inline unsigned long btrfs_header
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;
}
@@ -2830,12 +2833,12 @@ BTRFS_SETGET_STACK_FUNCS(root_stransid,
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;
}
@@ -2892,51 +2895,51 @@ BTRFS_SETGET_STACK_FUNCS(backup_num_devi
/* 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));

@@ -2954,7 +2957,7 @@ btrfs_disk_balance_args_to_cpu(struct bt

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));

@@ -3022,7 +3025,7 @@ BTRFS_SETGET_STACK_FUNCS(super_magic, st
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);
/*
@@ -3041,8 +3044,8 @@ static inline unsigned long btrfs_leaf_d
* 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_root *root,
- struct extent_buffer *leaf)
+static inline unsigned int leaf_data_end(const struct btrfs_root *root,
+ const struct extent_buffer *leaf)
{
u32 nr = btrfs_header_nritems(leaf);

@@ -3067,7 +3070,7 @@ BTRFS_SETGET_STACK_FUNCS(stack_file_exte
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;
}
@@ -3101,8 +3104,9 @@ BTRFS_SETGET_FUNCS(file_extent_other_enc
* 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;
}
@@ -3110,9 +3114,9 @@ static inline u32 btrfs_file_extent_inli
/* 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;

@@ -3134,8 +3138,8 @@ static inline u32 btrfs_file_extent_inli

/* 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;
--- a/fs/btrfs/extent_io.c
+++ b/fs/btrfs/extent_io.c
@@ -5111,9 +5111,8 @@ unlock_exit:
return ret;
}

-void read_extent_buffer(struct extent_buffer *eb, void *dstv,
- unsigned long start,
- unsigned long len)
+void read_extent_buffer(const struct extent_buffer *eb, void *dstv,
+ unsigned long start, unsigned long len)
{
size_t cur;
size_t offset;
@@ -5142,9 +5141,9 @@ void read_extent_buffer(struct extent_bu
}
}

-int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dstv,
- unsigned long start,
- unsigned long len)
+int read_extent_buffer_to_user(const struct extent_buffer *eb,
+ void __user *dstv,
+ unsigned long start, unsigned long len)
{
size_t cur;
size_t offset;
@@ -5179,10 +5178,10 @@ int read_extent_buffer_to_user(struct ex
return ret;
}

-int map_private_extent_buffer(struct extent_buffer *eb, unsigned long start,
- unsigned long min_len, char **map,
- unsigned long *map_start,
- unsigned long *map_len)
+int map_private_extent_buffer(const struct extent_buffer *eb,
+ unsigned long start, unsigned long min_len,
+ char **map, unsigned long *map_start,
+ unsigned long *map_len)
{
size_t offset = start & (PAGE_CACHE_SIZE - 1);
char *kaddr;
@@ -5217,9 +5216,8 @@ int map_private_extent_buffer(struct ext
return 0;
}

-int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
- unsigned long start,
- unsigned long len)
+int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
+ unsigned long start, unsigned long len)
{
size_t cur;
size_t offset;
--- a/fs/btrfs/extent_io.h
+++ b/fs/btrfs/extent_io.h
@@ -291,14 +291,13 @@ static inline void extent_buffer_get(str
atomic_inc(&eb->refs);
}

-int memcmp_extent_buffer(struct extent_buffer *eb, const void *ptrv,
- unsigned long start,
- unsigned long len);
-void read_extent_buffer(struct extent_buffer *eb, void *dst,
+int memcmp_extent_buffer(const struct extent_buffer *eb, const void *ptrv,
+ unsigned long start, unsigned long len);
+void read_extent_buffer(const struct extent_buffer *eb, void *dst,
unsigned long start,
unsigned long len);
-int read_extent_buffer_to_user(struct extent_buffer *eb, void __user *dst,
- unsigned long start,
+int read_extent_buffer_to_user(const struct extent_buffer *eb,
+ void __user *dst, unsigned long start,
unsigned long len);
void write_extent_buffer(struct extent_buffer *eb, const void *src,
unsigned long start, unsigned long len);
@@ -317,10 +316,10 @@ int set_extent_buffer_uptodate(struct ex
int clear_extent_buffer_uptodate(struct extent_buffer *eb);
int extent_buffer_uptodate(struct extent_buffer *eb);
int extent_buffer_under_io(struct extent_buffer *eb);
-int map_private_extent_buffer(struct extent_buffer *eb, unsigned long offset,
- unsigned long min_len, char **map,
- unsigned long *map_start,
- unsigned long *map_len);
+int map_private_extent_buffer(const struct extent_buffer *eb,
+ unsigned long offset, unsigned long min_len,
+ char **map, unsigned long *map_start,
+ unsigned long *map_len);
int extent_range_clear_dirty_for_io(struct inode *inode, u64 start, u64 end);
int extent_range_redirty_for_io(struct inode *inode, u64 start, u64 end);
int extent_clear_unlock_delalloc(struct inode *inode, u64 start, u64 end,
--- a/fs/btrfs/struct-funcs.c
+++ b/fs/btrfs/struct-funcs.c
@@ -50,8 +50,8 @@ static inline void put_unaligned_le8(u8
*/

#define DEFINE_BTRFS_SETGET_BITS(bits) \
-u##bits btrfs_get_token_##bits(struct extent_buffer *eb, void *ptr, \
- unsigned long off, \
+u##bits btrfs_get_token_##bits(const struct extent_buffer *eb, \
+ const void *ptr, unsigned long off, \
struct btrfs_map_token *token) \
{ \
unsigned long part_offset = (unsigned long)ptr; \
@@ -90,7 +90,8 @@ u##bits btrfs_get_token_##bits(struct ex
return res; \
} \
void btrfs_set_token_##bits(struct extent_buffer *eb, \
- void *ptr, unsigned long off, u##bits val, \
+ const void *ptr, unsigned long off, \
+ u##bits val, \
struct btrfs_map_token *token) \
{ \
unsigned long part_offset = (unsigned long)ptr; \
@@ -133,7 +134,7 @@ DEFINE_BTRFS_SETGET_BITS(16)
DEFINE_BTRFS_SETGET_BITS(32)
DEFINE_BTRFS_SETGET_BITS(64)

-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)
{
unsigned long ptr = btrfs_node_key_ptr_offset(nr);