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Btrfs: fix 64 bit divide problem 

This fixes a regression introduced by commit cdcb725c05 ("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>
This commit is contained in:
Josef Bacik 2011-08-20 08:29:51 -04:00 committed by Linus Torvalds
parent c063d8a60f
commit 6719db6a23
1 changed files with 7 additions and 5 deletions
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12
fs/btrfs/extent-tree.c
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@ -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);