[amir73il:fan_pre_modify 25/29] fs/namespace.c:491:5: warning: no previous prototype for function '__sb_mnt_want_write_file'

[kernel test robot <lkp@intel.com>]

tree:   https://github.com/amir73il/linux fan_pre_modify
head:   98a5f0e208bb7b3378da3912e93c51bc400b65cf
commit: d6522cc6094a6e54cfd1c352c24cc534deb67ff2 [25/29] fanotify: introduce FAN_PRE_ATTRIB permission event
config: hexagon-randconfig-r024-20230129 (https://download.01.org/0day-ci/archive/20230129/202301290718.bNi98Wyy-lkp@intel.com/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 4196ca3278f78c6e19246e54ab0ecb364e37d66a)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # https://github.com/amir73il/linux/commit/d6522cc6094a6e54cfd1c352c24cc534deb67ff2
        git remote add amir73il https://github.com/amir73il/linux
        git fetch --no-tags amir73il fan_pre_modify
        git checkout d6522cc6094a6e54cfd1c352c24cc534deb67ff2
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash

If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from fs/namespace.c:11:
   In file included from include/linux/syscalls.h:88:
   In file included from include/trace/syscall.h:7:
   In file included from include/linux/trace_events.h:9:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:547:31: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __raw_readb(PCI_IOBASE + addr);
                             ~~~~~~~~~~ ^
   include/asm-generic/io.h:560:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le16_to_cpu((__le16 __force)__raw_readw(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:37:51: note: expanded from macro '__le16_to_cpu'
   #define __le16_to_cpu(x) ((__force __u16)(__le16)(x))
                                                     ^
   In file included from fs/namespace.c:11:
   In file included from include/linux/syscalls.h:88:
   In file included from include/trace/syscall.h:7:
   In file included from include/linux/trace_events.h:9:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:573:61: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           val = __le32_to_cpu((__le32 __force)__raw_readl(PCI_IOBASE + addr));
                                                           ~~~~~~~~~~ ^
   include/uapi/linux/byteorder/little_endian.h:35:51: note: expanded from macro '__le32_to_cpu'
   #define __le32_to_cpu(x) ((__force __u32)(__le32)(x))
                                                     ^
   In file included from fs/namespace.c:11:
   In file included from include/linux/syscalls.h:88:
   In file included from include/trace/syscall.h:7:
   In file included from include/linux/trace_events.h:9:
   In file included from include/linux/hardirq.h:11:
   In file included from ./arch/hexagon/include/generated/asm/hardirq.h:1:
   In file included from include/asm-generic/hardirq.h:17:
   In file included from include/linux/irq.h:20:
   In file included from include/linux/io.h:13:
   In file included from arch/hexagon/include/asm/io.h:334:
   include/asm-generic/io.h:584:33: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writeb(value, PCI_IOBASE + addr);
                               ~~~~~~~~~~ ^
   include/asm-generic/io.h:594:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writew((u16 __force)cpu_to_le16(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
   include/asm-generic/io.h:604:59: warning: performing pointer arithmetic on a null pointer has undefined behavior [-Wnull-pointer-arithmetic]
           __raw_writel((u32 __force)cpu_to_le32(value), PCI_IOBASE + addr);
                                                         ~~~~~~~~~~ ^
>> fs/namespace.c:491:5: warning: no previous prototype for function '__sb_mnt_want_write_file' [-Wmissing-prototypes]
   int __sb_mnt_want_write_file(struct file *file)
       ^
   fs/namespace.c:491:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int __sb_mnt_want_write_file(struct file *file)
   ^
   static 
   7 warnings generated.


vim +/__sb_mnt_want_write_file +491 fs/namespace.c

   481	
   482	/**
   483	 * __sb_mnt_want_write_file - get write access to a file's mount and sb
   484	 * @file: the file who's mount on which to take a write
   485	 *
   486	 * This is like mnt_want_write, but if the file is already open for writing it
   487	 * skips incrementing mnt_writers (since the open file already has a reference)
   488	 * and instead only does the freeze protection and the check for emergency r/o
   489	 * remounts.  This must be paired with mnt_drop_write_file.
   490	 */
 > 491	int __sb_mnt_want_write_file(struct file *file)
   492	{
   493		int ret;
   494	
   495		sb_start_write(file_inode(file)->i_sb);
   496		ret = __mnt_want_write_file(file);
   497		if (ret)
   498			sb_end_write(file_inode(file)->i_sb);
   499		return ret;
   500	}
   501	

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