Commit 6affb9d7 authored Jan 24, 2017 by Ross Zwisler Committed by Linus Torvalds Jan 24, 2017

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.

Link: http://lkml.kernel.org/r/1484087383-29478-1-git-send-email-ross.zwisler@linux.intel.com


Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 8310d48b

fs/Kconfig

+1 −0

Original line number	Diff line number	Diff line
		@@ -38,6 +38,7 @@ config FS_DAX
		bool "Direct Access (DAX) support"
		depends on MMU
		depends on !(ARM \|\| MIPS \|\| SPARC)
		select FS_IOMAP
		help
		Direct Access (DAX) can be used on memory-backed block devices.
		If the block device supports DAX and the filesystem supports DAX,

fs/dax.c

+0 −2

Original line number	Diff line number	Diff line
		@@ -990,7 +990,6 @@ int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
		}
		EXPORT_SYMBOL_GPL(__dax_zero_page_range);

		#ifdef CONFIG_FS_IOMAP
		static sector_t dax_iomap_sector(struct iomap *iomap, loff_t pos)
		{
		return iomap->blkno + (((pos & PAGE_MASK) - iomap->offset) >> 9);
		@@ -1428,4 +1427,3 @@ int dax_iomap_pmd_fault(struct vm_area_struct *vma, unsigned long address,
		}
		EXPORT_SYMBOL_GPL(dax_iomap_pmd_fault);
		#endif /* CONFIG_FS_DAX_PMD */
		#endif /* CONFIG_FS_IOMAP */

fs/ext2/Kconfig

+0 −1

Original line number	Diff line number	Diff line
		config EXT2_FS
		tristate "Second extended fs support"
		select FS_IOMAP if FS_DAX
		help
		Ext2 is a standard Linux file system for hard disks.

fs/ext4/Kconfig

+0 −1

Original line number	Diff line number	Diff line
		@@ -37,7 +37,6 @@ config EXT4_FS
		select CRC16
		select CRYPTO
		select CRYPTO_CRC32C
		select FS_IOMAP if FS_DAX
		help
		This is the next generation of the ext3 filesystem.

Admin message