On Tue 10-01-17 15:29:43, Ross Zwisler wrote:
> 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.zwis...@linux.intel.com>
> Reported-by: Arnd Bergmann <a...@arndb.de>
> Cc: Jan Kara <j...@suse.cz>
> Cc: Christoph Hellwig <h...@lst.de>
Looks good. I agree that DAX without FS_IOMAP does not make sense. You can
add:
Reviewed-by: Jan Kara <j...@suse.cz>
Honza
> ---
> fs/Kconfig | 1 +
> fs/dax.c | 2 --
> fs/ext2/Kconfig | 1 -
> fs/ext4/Kconfig | 1 -
> 4 files changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/fs/Kconfig b/fs/Kconfig
> index c2a377c..83eab52 100644
> --- a/fs/Kconfig
> +++ b/fs/Kconfig
> @@ -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,
> diff --git a/fs/dax.c b/fs/dax.c
> index 5c74f60..083b950 100644
> --- a/fs/dax.c
> +++ b/fs/dax.c
> @@ -969,7 +969,6 @@ 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);
> @@ -1407,4 +1406,3 @@ 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 */
> diff --git a/fs/ext2/Kconfig b/fs/ext2/Kconfig
> index 36bea5a..c634874e 100644
> --- a/fs/ext2/Kconfig
> +++ b/fs/ext2/Kconfig
> @@ -1,6 +1,5 @@
> 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.
>
> diff --git a/fs/ext4/Kconfig b/fs/ext4/Kconfig
> index 7b90691..e38039f 100644
> --- a/fs/ext4/Kconfig
> +++ b/fs/ext4/Kconfig
> @@ -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.
>
> --
> 2.7.4
>
--
Jan Kara <j...@suse.com>
SUSE Labs, CR
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