Hi Miklos,

I love your patch! Yet something to improve:

[auto build test ERROR on fuse/for-next]
[cannot apply to v4.20-rc7 next-20181219]
[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: x86_64-allmodconfig (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=x86_64 

All error/warnings (new ones prefixed by >>):

>> fs/ext2/inode.c:959:54: warning: incorrect type in argument 3 (different base types)
   fs/ext2/inode.c:959:54:    expected struct dax_device *dax_dev
   fs/ext2/inode.c:959:54:    got struct writeback_control *wbc
>> fs/ext2/inode.c:958:43: error: not enough arguments for function dax_writeback_mapping_range
   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:87:5: note: expected 'struct dax_device *' but argument is of type 'struct writeback_control *'
    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:87:5: note: declared here
    int dax_writeback_mapping_range(struct address_space *mapping,
        ^~~~~~~~~~~~~~~~~~~~~~~~~~~
   fs/ext2/inode.c:960:1: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^
   cc1: some warnings being treated as errors
--
   include/linux/slab.h:332:43: warning: dubious: x & !y
   include/linux/slab.h:332:43: warning: dubious: x & !y
   include/linux/slab.h:332:43: warning: dubious: x & !y
   include/linux/slab.h:332:43: warning: dubious: x & !y
>> fs/fuse/file.c:3793:5: warning: symbol 'fuse_dax_reclaim_dmap_locked' was not declared. Should it be static?
>> fs/fuse/file.c:3825:25: warning: symbol 'fuse_dax_reclaim_first_mapping_locked' was not declared. Should it be static?
>> fs/fuse/file.c:3862:25: warning: symbol 'fuse_dax_reclaim_first_mapping' was not declared. Should it be static?
>> fs/fuse/file.c:3901:5: warning: symbol 'fuse_dax_free_one_mapping_locked' was not declared. Should it be static?
>> fs/fuse/file.c:3946:5: warning: symbol 'fuse_dax_free_one_mapping' was not declared. Should it be static?
>> fs/fuse/file.c:3967:5: warning: symbol 'fuse_dax_free_memory' was not declared. Should it be static?

vim +958 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 958 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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