Commit 6affb9d7 authored by Ross Zwisler's avatar Ross Zwisler Committed by Linus Torvalds

dax: fix build warnings with FS_DAX and !FS_IOMAP

As reported by Arnd:

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

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: default avatarRoss Zwisler <>
Reported-by: default avatarArnd Bergmann <>
Reviewed-by: default avatarChristoph Hellwig <>
Reviewed-by: default avatarJan Kara <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 8310d48b
......@@ -38,6 +38,7 @@ config FS_DAX
bool "Direct Access (DAX) support"
depends on MMU
depends on !(ARM || MIPS || SPARC)
select FS_IOMAP
Direct Access (DAX) can be used on memory-backed block devices.
If the block device supports DAX and the filesystem supports DAX,
......@@ -990,7 +990,6 @@ int __dax_zero_page_range(struct block_device *bdev, sector_t sector,
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,
#endif /* CONFIG_FS_DAX_PMD */
#endif /* CONFIG_FS_IOMAP */
config EXT2_FS
tristate "Second extended fs support"
select FS_IOMAP if FS_DAX
Ext2 is a standard Linux file system for hard disks.
......@@ -37,7 +37,6 @@ config EXT4_FS
select CRC16
select CRYPTO
select CRYPTO_CRC32C
select FS_IOMAP if FS_DAX
This is the next generation of the ext3 filesystem.
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