Hi Vivek,

I love your patch! Yet something to improve:

[auto build test ERROR on fuse/for-next]
[also build test ERROR on v4.20-rc6]
[cannot apply to next-20181210]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Vivek-Goyal/virtio-fs-shared-file-system-for-virtual-machines/20181211-103034
base:   https://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/fuse.git for-next
config: i386-randconfig-x006-201849 (attached as .config)
compiler: gcc-7 (Debian 7.3.0-1) 7.3.0
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   fs//ext2/inode.c: In function 'ext2_dax_writepages':
>> fs//ext2/inode.c:959:33: error: passing argument 3 of 'dax_writeback_mapping_range' from incompatible pointer type [-Werror=incompatible-pointer-types]
       mapping->host->i_sb->s_bdev, wbc);
                                    ^~~
   In file included from fs//ext2/inode.c:29:0:
   include/linux/dax.h:120:19: note: expected 'struct dax_device *' but argument is of type 'struct writeback_control *'
    static inline int dax_writeback_mapping_range(struct address_space *mapping,
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
>> fs//ext2/inode.c:958:9: error: too few arguments to function 'dax_writeback_mapping_range'
     return dax_writeback_mapping_range(mapping,
            ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   In file included from fs//ext2/inode.c:29:0:
   include/linux/dax.h:120:19: note: declared here
    static inline int dax_writeback_mapping_range(struct address_space *mapping,
                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   cc1: some warnings being treated as errors

vim +/dax_writeback_mapping_range +959 fs//ext2/inode.c

7f6d5b52 Ross Zwisler   2016-02-26  954  
fb094c90 Dan Williams   2017-12-21  955  static int
fb094c90 Dan Williams   2017-12-21  956  ext2_dax_writepages(struct address_space *mapping, struct writeback_control *wbc)
fb094c90 Dan Williams   2017-12-21  957  {
fb094c90 Dan Williams   2017-12-21 @958  	return dax_writeback_mapping_range(mapping,
fb094c90 Dan Williams   2017-12-21 @959  			mapping->host->i_sb->s_bdev, wbc);
^1da177e Linus Torvalds 2005-04-16  960  }
^1da177e Linus Torvalds 2005-04-16  961  

:::::: The code at line 959 was first introduced by commit
:::::: fb094c90748fbeba1063927eeb751add147b35b9 ext2, dax: introduce ext2_dax_aops

:::::: TO: Dan Williams <dan.j.williams@intel.com>
:::::: CC: Dan Williams <dan.j.williams@intel.com>

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