• Arnd Bergmann's avatar
    btrfs: avoid link error with CONFIG_NO_AUTO_INLINE · 7e17916b
    Arnd Bergmann authored
    Note: this patch fixes a problem in a feature outside of btrfs ("kernel
    hacking: add a config option to disable compiler auto-inlining") and is
    applied ahead of time due to cross-subsystem dependencies.
    
    On 32-bit ARM with gcc-8, I see a link error with the addition of the
    CONFIG_NO_AUTO_INLINE option:
    
    fs/btrfs/super.o: In function `btrfs_statfs':
    super.c:(.text+0x67b8): undefined reference to `__aeabi_uldivmod'
    super.c:(.text+0x67fc): undefined reference to `__aeabi_uldivmod'
    super.c:(.text+0x6858): undefined reference to `__aeabi_uldivmod'
    super.c:(.text+0x6920): undefined reference to `__aeabi_uldivmod'
    super.c:(.text+0x693c): undefined reference to `__aeabi_uldivmod'
    fs/btrfs/super.o:super.c:(.text+0x6958): more undefined references to `__aeabi_uldivmod' follow
    
    So far this is the only file that shows the behavior, so I'd propose
    to just work around it by marking the functions as 'static inline'
    that normally get inlined here.
    
    The reference to __aeabi_uldivmod comes from a div_u64() which has an
    optimization for a constant division that uses a straight '/' operator
    when the result should be known to the compiler. My interpretation is
    that as we turn off inlining, gcc still expects the result to be constant
    but fails to use that constant value.
    
    Link: https://lkml.kernel.org/r/20181103153941.1881966-1-arnd@arndb.deReviewed-by: default avatarNikolay Borisov <nborisov@suse.com>
    Reviewed-by: default avatarChangbin Du <changbin.du@gmail.com>
    Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
    [ add the note ]
    Signed-off-by: default avatarDavid Sterba <dsterba@suse.com>
    7e17916b
super.c 65.5 KB