shmem: export shmem_kernel_file_setup

XFS wants to use this for it's internal in-memory data structures and
currently duplicates the functionality.  Export shmem_kernel_file_setup
to allow XFS to switch over to using the proper kernel API.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>

mm/shmem.c

@@ -4861,6 +4861,7 @@ struct file *shmem_kernel_file_setup(const char *name, loff_t size, unsigned lon
 {
 	return __shmem_file_setup(shm_mnt, name, size, flags, S_PRIVATE);
 }
+EXPORT_SYMBOL_GPL(shmem_kernel_file_setup);
 
 /**
  * shmem_file_setup - get an unlinked file living in tmpfs