xfs: make mem_to_page available outside of xfs_buf.c

Rename the function to kmem_to_page and move it to kmem.h together
with our kmem_large allocator that may either return kmalloced or
vmalloc pages.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/kmem.h

@@ -124,4 +124,12 @@ kmem_zone_zalloc(kmem_zone_t *zone, xfs_km_flags_t flags)
 	return kmem_zone_alloc(zone, flags | KM_ZERO);
 }
 
+static inline struct page *
+kmem_to_page(void *addr)
+{
+	if (is_vmalloc_addr(addr))
+		return vmalloc_to_page(addr);
+	return virt_to_page(addr);
+}
+
 #endif /* __XFS_SUPPORT_KMEM_H__ */

fs/xfs/xfs_buf.c

@@ -934,17 +934,6 @@ xfs_buf_set_empty(
 	bp->b_maps[0].bm_len = bp->b_length;
 }
 
-static inline struct page *
-mem_to_page(
-	void			*addr)
-{
-	if ((!is_vmalloc_addr(addr))) {
-		return virt_to_page(addr);
-	} else {
-		return vmalloc_to_page(addr);
-	}
-}
-
 int
 xfs_buf_associate_memory(
 	xfs_buf_t		*bp,
@@ -977,7 +966,7 @@ xfs_buf_associate_memory(
 	bp->b_offset = offset;
 
 	for (i = 0; i < bp->b_page_count; i++) {
-		bp->b_pages[i] = mem_to_page((void *)pageaddr);
+		bp->b_pages[i] = kmem_to_page((void *)pageaddr);
 		pageaddr += PAGE_SIZE;
 	}