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btrfs: qgroup: fix quota disable during rescan 

There's a race condition that leads to a NULL pointer dereference if you
disable quotas while a quota rescan is running.  To fix this, we just need
to wait for the quota rescan worker to actually exit before tearing down
the quota structures.

Signed-off-by: Justin Maggard <jmaggard@netgear.com>
Signed-off-by: Chris Mason <clm@fb.com>
hifive-unleashed-5.1
Justin Maggard 2015-11-06 10:36:42 -08:00 committed by Chris Mason
parent 036a9348dc
commit 967ef5131e
1 changed files with 2 additions and 1 deletions
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3
fs/btrfs/qgroup.c
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@ -993,9 +993,10 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans,
mutex_lock(&fs_info->qgroup_ioctl_lock);
if (!fs_info->quota_root)
goto out;
spin_lock(&fs_info->qgroup_lock);
fs_info->quota_enabled = 0;
fs_info->pending_quota_state = 0;
btrfs_qgroup_wait_for_completion(fs_info);
spin_lock(&fs_info->qgroup_lock);
quota_root = fs_info->quota_root;
fs_info->quota_root = NULL;
fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_ON;