[PATCH v2] pnfs/blocklayout: Fix a 64-bit division/remainder issue in bl_map_stripe

Trond Myklebust
2014-09-18T21:15:53Z

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'

Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
---
v2: Include the calculation of disk_offset.

fs/nfs/blocklayout/dev.c | 9 ++++++---
1 file 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);
--
1.9.3