linux-kernel - [PATCH][linux-next] pnfs/blocklayout: Use do

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Date:	Fri, 19 Sep 2014 13:30:46 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	LKML <linux-kernel@...r.kernel.org>, linux-nfs@...r.kernel.org
Cc:	Trond Myklebust <trond.myklebust@...marydata.com>,
	Christoph Hellwig <hch@...radead.org>
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 <rostedt@...dmis.org>
---
 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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