[PATCH] btrfs: use the correct const function attribute for btrfs_get_num_csums

[David Sterba <dsterba@suse.com>]

The build robot reports

compiler: h8300-linux-gcc (GCC) 9.3.0
   In file included from fs/btrfs/tests/extent-map-tests.c:8:
>> fs/btrfs/tests/../ctree.h:2166:8: warning: type qualifiers ignored on function return type [-Wignored-qualifiers]
    2166 | size_t __const btrfs_get_num_csums(void);
         |        ^~~~~~~

The function attribute for const does not follow the expected scheme and
in this case is confused with a const type qualifier.

Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/ctree.c | 2 +-
 fs/btrfs/ctree.h | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 70e49d8d4f6c..cd1cd673bc0b 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -68,7 +68,7 @@ const char *btrfs_super_csum_driver(u16 csum_type)
 		btrfs_csums[csum_type].name;
 }
 
-size_t __const btrfs_get_num_csums(void)
+size_t __attribute_const__ btrfs_get_num_csums(void)
 {
 	return ARRAY_SIZE(btrfs_csums);
 }
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 9c7e466f27a9..729b5b80014a 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -2262,7 +2262,7 @@ BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
 int btrfs_super_csum_size(const struct btrfs_super_block *s);
 const char *btrfs_super_csum_name(u16 csum_type);
 const char *btrfs_super_csum_driver(u16 csum_type);
-size_t __const btrfs_get_num_csums(void);
+size_t __attribute_const__ btrfs_get_num_csums(void);
 
 
 /*
-- 
2.25.0