From 6719db6a23d4b7f1e5052eedae394135e3aef9c1 Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@redhat.com>
Date: Sat, 20 Aug 2011 08:29:51 -0400
Subject: [PATCH] Btrfs: fix 64 bit divide problem
This fixes a regression introduced by commit cdcb725c05fe ("Btrfs: check
if there is enough space for balancing smarter"). We can't do 64-bit
divides on 32-bit architectures.
In cases where we need to divide/multiply by 2 we should just left/right
shift respectively, and in cases where theres N number of devices use
do_div. Also make the counters u64 to match up with rw_devices.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Acked-and-tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---
fs/btrfs/extent-tree.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 80d6148f60ac..f5be06a2462f 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -6735,9 +6735,9 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices;
struct btrfs_device *device;
u64 min_free;
+ u64 dev_min = 1;
+ u64 dev_nr = 0;
int index;
- int dev_nr = 0;
- int dev_min = 1;
int full = 0;
int ret = 0;
@@ -6796,14 +6796,16 @@ int btrfs_can_relocate(struct btrfs_root *root, u64 bytenr)
index = get_block_group_index(block_group);
if (index == 0) {
dev_min = 4;
- min_free /= 2;
+ /* Divide by 2 */
+ min_free >>= 1;
} else if (index == 1) {
dev_min = 2;
} else if (index == 2) {
- min_free *= 2;
+ /* Multiply by 2 */
+ min_free <<= 1;
} else if (index == 3) {
dev_min = fs_devices->rw_devices;
- min_free /= dev_min;
+ do_div(min_free, dev_min);
}
mutex_lock(&root->fs_info->chunk_mutex);
--
2.20.1