[PATCH][linux-next] pnfs/blocklayout: Use do_div for 64 bit divide operations

From: Steven Rostedt
Date: Fri Sep 19 2014 - 13:30:51 EST



Commit 5c83746a0cf2 "pnfs/blocklayout: in-kernel GETDEVICEINFO XDR parsing"
added some open coded 64 bit divisions which caused the following
error on 32 bit builds:

fs/built-in.o: In function `bl_map_stripe':
fs/nfs/blocklayout/dev.c:153: undefined reference to `__udivdi3'
fs/nfs/blocklayout/dev.c:154: undefined reference to `__umoddi3'
fs/nfs/blocklayout/dev.c:168: undefined reference to `__udivdi3'

Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
---
fs/nfs/blocklayout/dev.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/blocklayout/dev.c b/fs/nfs/blocklayout/dev.c
index 00f159da06ee..05d32e2175db 100644
--- a/fs/nfs/blocklayout/dev.c
+++ b/fs/nfs/blocklayout/dev.c
@@ -150,10 +150,18 @@ 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;
+ u64 chunk_tmp;
+ int chunk_idx;
u64 disk_offset;

+ chunk = offset;
+ /* chunk = offset / dev->chunk_size */
+ do_div(chunk, dev->chunk_size);
+ chunk_tmp = chunk;
+ /* chunk_idx = chunk % dev->nr_children) */
+ chunk_idx = do_div(chunk_tmp, dev->nr_children);
+
if (chunk_idx > dev->nr_children) {
dprintk("%s: invalid chunk idx %d (%lld/%lld)\n",
__func__, chunk_idx, offset, dev->chunk_size);
@@ -165,7 +173,9 @@ 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 = offset;
+ /* disk_offset = offset / dev->nr_children */
+ do_div(disk_offset, dev->nr_children);

child = &dev->children[chunk_idx];
child->map(child, disk_offset, map);
--
1.8.1.4

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