On Tue, 2016-04-12 at 23:01 -0400, Matthew Wilcox wrote:
> On Tue, Apr 12, 2016 at 02:39:29PM -0600, Toshi Kani wrote:
> >
> > To support DAX pmd mappings with unmodified applications,
> > filesystems need to align an mmap address by the pmd size.
> >
> > @@ -708,6 +708,9 @@ const struct file_operations ext4_file_operations =
> > {
> > .open = ext4_file_open,
> > .release = ext4_release_file,
> > .fsync = ext4_sync_file,
> > +#ifdef CONFIG_FS_DAX
> > + .get_unmapped_area = dax_get_unmapped_area,
> > +#endif
> > .splice_read = generic_file_splice_read,
> > .splice_write = iter_file_splice_write,
> > .fallocate = ext4_fallocate,
>
> Could you do something like:
>
> #ifdef CONFIG_FS_DAX
> struct page *read_dax_sector(struct block_device *bdev, sector_t n);
> +unsigned long dax_get_unmapped_area(struct file *filp, unsigned long
> addr,
> + unsigned long len, unsigned long pgoff, unsigned long
> flags);
> #else
> static inline struct page *read_dax_sector(struct block_device *bdev,
> sector_t n)
> {
> return ERR_PTR(-ENXIO);
> }
> +#define dax_get_unmapped_area NULL
> #endif
>
> in patch 1/5. Then there's no need for the ifdefs in each filesystem.
I thought about it, but I do not think we can use an inline function to an
entry point.
Thanks,
-Toshi
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