tjh.dev / kernel
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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>

authored by

Josef Bacik and committed by
Linus Torvalds 6719db6a c063d8a6

+7 -5
+7 -5
fs/btrfs/extent-tree.c
··· 6735 6735 struct btrfs_fs_devices *fs_devices = root->fs_info->fs_devices; 6736 6736 struct btrfs_device *device; 6737 6737 u64 min_free; 6738 + u64 dev_min = 1; 6739 + u64 dev_nr = 0; 6738 6740 int index; 6739 - int dev_nr = 0; 6740 - int dev_min = 1; 6741 6741 int full = 0; 6742 6742 int ret = 0; 6743 6743 ··· 6796 6796 index = get_block_group_index(block_group); 6797 6797 if (index == 0) { 6798 6798 dev_min = 4; 6799 - min_free /= 2; 6799 + /* Divide by 2 */ 6800 + min_free >>= 1; 6800 6801 } else if (index == 1) { 6801 6802 dev_min = 2; 6802 6803 } else if (index == 2) { 6803 - min_free *= 2; 6804 + /* Multiply by 2 */ 6805 + min_free <<= 1; 6804 6806 } else if (index == 3) { 6805 6807 dev_min = fs_devices->rw_devices; 6806 - min_free /= dev_min; 6808 + do_div(min_free, dev_min); 6807 6809 } 6808 6810 6809 6811 mutex_lock(&root->fs_info->chunk_mutex);