tree a0328b4be5887a5782211566073d29edad3910c8
parent a121103c922847ba5010819a3f250f1f7fc84ab8
author Ross Zwisler <ross.zwisler@linux.intel.com> 1484086433 -0700
committer Ross Zwisler <ross.zwisler@linux.intel.com> 1484087115 -0700

dax: fix build warnings with FS_DAX and !FS_IOMAP

As reported by Arnd:

https://lkml.org/lkml/2017/1/10/756

Compiling with the following configuration:

  # CONFIG_EXT2_FS is not set
  # CONFIG_EXT4_FS is not set
  # CONFIG_XFS_FS is not set
  # CONFIG_FS_IOMAP depends on the above filesystems, as is not set
  CONFIG_FS_DAX=y

generates build warnings about unused functions in fs/dax.c:

fs/dax.c:878:12: warning: ‘dax_insert_mapping’ defined but not used [-Wunused-function]
 static int dax_insert_mapping(struct address_space *mapping,
            ^~~~~~~~~~~~~~~~~~
fs/dax.c:572:12: warning: ‘copy_user_dax’ defined but not used [-Wunused-function]
 static int copy_user_dax(struct block_device *bdev, sector_t sector, size_t size,
            ^~~~~~~~~~~~~
fs/dax.c:542:12: warning: ‘dax_load_hole’ defined but not used [-Wunused-function]
 static int dax_load_hole(struct address_space *mapping, void **entry,
            ^~~~~~~~~~~~~
fs/dax.c:312:14: warning: ‘grab_mapping_entry’ defined but not used [-Wunused-function]
 static void *grab_mapping_entry(struct address_space *mapping, pgoff_t index,
              ^~~~~~~~~~~~~~~~~~

Now that the struct buffer_head based DAX fault paths and I/O path have
been removed we really depend on iomap support being present for DAX.  Make
this explicit by selecting FS_IOMAP if we compile in DAX support.

This allows us to remove conditional selections of FS_IOMAP when FS_DAX was
present for ext2 and ext4, and to remove an #ifdef in fs/dax.c.

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>