From f5e60e8d7080d29739a4f056d5dbc28eafd4578e Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 25 Aug 2026 13:42:31 +0930 Subject: btrfs: qgroup: use atomic operations for btrfs_fs_info::qgroup_flags Currently we define btrfs_fs_info::qgroup_flags as u64, to match the on-disk qgroup status item's flag. But for now we have only 4 bits utilized for that flag, and since it's u64 we have no way to properly use the existing atomic bit operations (requires an unsigned long pointer). This results in a lot of non-atomic operations inside qgroup code. Some maybe fine as other locks are involved, but still it's not a good practice. Remove those non-atomic operations by: - Re-define btrfs_fs_info::qgroup_flags as unsigned long - Define BTRFS_QGROUP_STATUS_BIT_* and BTRFS_QGROUP_RUNTIME_BIT_* Instead of the old value define the bit number. - Use set_bit()/clear_bit()/test_bit() to replace open-coded bit operations - Add one extra check at qgroup status item read time To make sure the on-disk flag is still inside ULONG_MAX. Otherwise reject the status item and disable qgroup. - Get rid of unnecessary spinlock when checking a single bit Reviewed-by: Johannes Thumshirn Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba --- fs/btrfs/sysfs.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) (limited to 'fs/btrfs/sysfs.c') diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c index 39cb01ee441a..1df6340a7123 100644 --- a/fs/btrfs/sysfs.c +++ b/fs/btrfs/sysfs.c @@ -2359,9 +2359,7 @@ static ssize_t qgroup_enabled_show(struct kobject *qgroups_kobj, struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent); bool enabled; - spin_lock(&fs_info->qgroup_lock); - enabled = fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON; - spin_unlock(&fs_info->qgroup_lock); + enabled = test_bit(BTRFS_QGROUP_STATUS_BIT_ON, &fs_info->qgroup_flags); return sysfs_emit(buf, "%d\n", enabled); } @@ -2401,9 +2399,7 @@ static ssize_t qgroup_inconsistent_show(struct kobject *qgroups_kobj, struct btrfs_fs_info *fs_info = to_fs_info(qgroups_kobj->parent); bool inconsistent; - spin_lock(&fs_info->qgroup_lock); - inconsistent = (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT); - spin_unlock(&fs_info->qgroup_lock); + inconsistent = test_bit(BTRFS_QGROUP_STATUS_BIT_INCONSISTENT, &fs_info->qgroup_flags); return sysfs_emit(buf, "%d\n", inconsistent); } -- cgit v1.2.3