Hi Christoph,

I love your patch! Yet something to improve:

[auto build test ERROR on axboe-block/for-next]
[also build test ERROR on linus/master v5.15-rc2 next-20210920]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Christoph-Hellwig/nvdimm-pmem-fix-creating-the-dax-group/20210920-162804
base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
config: riscv-buildonly-randconfig-r006-20210920 (attached as .config)
compiler: riscv64-linux-gcc (GCC) 11.2.0
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/0day-ci/linux/commit/1a16d0f32f70bcd159a9f8cf32794f4024e8711e
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Christoph-Hellwig/nvdimm-pmem-fix-creating-the-dax-group/20210920-162804
        git checkout 1a16d0f32f70bcd159a9f8cf32794f4024e8711e
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.2.0 make.cross ARCH=riscv 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <redacted>

All errors (new ones prefixed by >>):

   drivers/dax/super.c:375:6: error: no previous prototype for 'run_dax' [-Werror=missing-prototypes]
     375 | void run_dax(struct dax_device *dax_dev)
         |      ^~~~~~~

quoted

drivers/dax/super.c:70:27: error: 'dax_get_by_host' defined but not used [-Werror=unused-function]

      70 | static struct dax_device *dax_get_by_host(const char *host)
         |                           ^~~~~~~~~~~~~~~
   cc1: all warnings being treated as errors


vim +/dax_get_by_host +70 drivers/dax/super.c

1b7646014e0d838b Christoph Hellwig 2021-08-26  65  
1b7646014e0d838b Christoph Hellwig 2021-08-26  66  /**
1b7646014e0d838b Christoph Hellwig 2021-08-26  67   * dax_get_by_host() - temporary lookup mechanism for filesystem-dax
1b7646014e0d838b Christoph Hellwig 2021-08-26  68   * @host: alternate name for the device registered by a dax driver
1b7646014e0d838b Christoph Hellwig 2021-08-26  69   */
1b7646014e0d838b Christoph Hellwig 2021-08-26 @70  static struct dax_device *dax_get_by_host(const char *host)
1b7646014e0d838b Christoph Hellwig 2021-08-26  71  {
1b7646014e0d838b Christoph Hellwig 2021-08-26  72  	struct dax_device *dax_dev, *found = NULL;
1b7646014e0d838b Christoph Hellwig 2021-08-26  73  	int hash, id;
1b7646014e0d838b Christoph Hellwig 2021-08-26  74  
1b7646014e0d838b Christoph Hellwig 2021-08-26  75  	if (!host)
1b7646014e0d838b Christoph Hellwig 2021-08-26  76  		return NULL;
1b7646014e0d838b Christoph Hellwig 2021-08-26  77  
1b7646014e0d838b Christoph Hellwig 2021-08-26  78  	hash = dax_host_hash(host);
1b7646014e0d838b Christoph Hellwig 2021-08-26  79  
1b7646014e0d838b Christoph Hellwig 2021-08-26  80  	id = dax_read_lock();
1b7646014e0d838b Christoph Hellwig 2021-08-26  81  	spin_lock(&dax_host_lock);
1b7646014e0d838b Christoph Hellwig 2021-08-26  82  	hlist_for_each_entry(dax_dev, &dax_host_list[hash], list) {
1b7646014e0d838b Christoph Hellwig 2021-08-26  83  		if (!dax_alive(dax_dev)
1b7646014e0d838b Christoph Hellwig 2021-08-26  84  				|| strcmp(host, dax_dev->host) != 0)
1b7646014e0d838b Christoph Hellwig 2021-08-26  85  			continue;
1b7646014e0d838b Christoph Hellwig 2021-08-26  86  
1b7646014e0d838b Christoph Hellwig 2021-08-26  87  		if (igrab(&dax_dev->inode))
1b7646014e0d838b Christoph Hellwig 2021-08-26  88  			found = dax_dev;
1b7646014e0d838b Christoph Hellwig 2021-08-26  89  		break;
1b7646014e0d838b Christoph Hellwig 2021-08-26  90  	}
1b7646014e0d838b Christoph Hellwig 2021-08-26  91  	spin_unlock(&dax_host_lock);
1b7646014e0d838b Christoph Hellwig 2021-08-26  92  	dax_read_unlock(id);
1b7646014e0d838b Christoph Hellwig 2021-08-26  93  
1b7646014e0d838b Christoph Hellwig 2021-08-26  94  	return found;
1b7646014e0d838b Christoph Hellwig 2021-08-26  95  }
1b7646014e0d838b Christoph Hellwig 2021-08-26  96  

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