2014-09-19 17:30:48

by Steven Rostedt

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

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 <[email protected]>
---
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

2014-09-19 19:05:15

by Steven Rostedt

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

On Fri, 19 Sep 2014 14:39:10 -0400
Trond Myklebust <[email protected]> wrote:

> Thanks. I posted a similar bugfix on the linux-nfs mailing list
> yesterday. That hasn't been pushed to linux-next yet because Christoph
> wanted to run it through some QA tests first.

No problem. As long as it gets fixed before it breaks my test suite ;-)

-- Steve

2014-09-19 18:39:11

by Trond Myklebust

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

Hi Steven,

On Fri, Sep 19, 2014 at 1:30 PM, Steven Rostedt <[email protected]> wrote:
>
> 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 <[email protected]>
> ---
> 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
>

Thanks. I posted a similar bugfix on the linux-nfs mailing list
yesterday. That hasn't been pushed to linux-next yet because Christoph
wanted to run it through some QA tests first.

Cheers
Trond

--
Trond Myklebust

Linux NFS client maintainer, PrimaryData

[email protected]