pnfs/blocklayout: Fix a 64-bit division/remainder issue in bl_map_stripe

kbuild test robot reports:

   fs/built-in.o: In function `bl_map_stripe':
   >> :(.text+0x965b4): undefined reference to `__aeabi_uldivmod'
   >> :(.text+0x965cc): undefined reference to `__aeabi_uldivmod'
   >> :(.text+0x96604): undefined reference to `__aeabi_uldivmod'

Fixes: 5c83746a0cf2 (pnfs/blocklayout: in-kernel GETDEVICEINFO XDR parsing)
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>

1 files changed, 6 insertions, 3 deletions

diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c
index 00f159da06ee..5aed4f98df41 100644
--- a/fs/nfs/blocklayout/dev.c
+++ b/fs/nfs/blocklayout/dev.c
@@ -150,10 +150,13 @@ static bool bl_map_stripe(struct pnfs_block_dev *dev, u64 offset,
                 struct pnfs_block_dev_map *map)
 {
         struct pnfs_block_dev *child;
-        u64 chunk = (offset / dev->chunk_size);
-        int chunk_idx = chunk % dev->nr_children;
+        u64 chunk;
+        u32 chunk_idx;
         u64 disk_offset;
 
+        chunk = div_u64(offset, dev->chunk_size);
+        div_u64_rem(chunk, dev->nr_children, &chunk_idx);
+
         if (chunk_idx > dev->nr_children) {
                 dprintk("%s: invalid chunk idx %d (%lld/%lld)\n",
                         __func__, chunk_idx, offset, dev->chunk_size);
@@ -165,7 +168,7 @@ static bool bl_map_stripe(struct pnfs_block_dev *dev, u64 offset,
         offset = chunk * dev->chunk_size;
 
         /* disk offset of the stripe */
-        disk_offset = offset / dev->nr_children;
+        disk_offset = div_u64(offset, dev->nr_children);
 
         child = &dev->children[chunk_idx];
         child->map(child, disk_offset, map);