From fa25625f536ab4ea569b66dca7831a91d13432e8 Mon Sep 17 00:00:00 2001 From: Qu Wenruo Date: Tue, 10 Sep 2024 15:21:04 +0930 Subject: [PATCH] btrfs: qgroup: set a more sane default value for subtree drop threshold BugLink: https://bugs.launchpad.net/bugs/2097575 commit 5f9062a48db260fd6b53d86ecfb4d5dc59266316 upstream. Since commit 011b46c30476 ("btrfs: skip subtree scan if it's too high to avoid low stall in btrfs_commit_transaction()"), btrfs qgroup can automatically skip large subtree scan at the cost of marking qgroup inconsistent. It's designed to address the final performance problem of snapshot drop with qgroup enabled, but to be safe the default value is BTRFS_MAX_LEVEL, requiring a user space daemon to set a different value to make it work. I'd say it's not a good idea to rely on user space tool to set this default value, especially when some operations (snapshot dropping) can be triggered immediately after mount, leaving a very small window to that that sysfs interface. So instead of disabling this new feature by default, enable it with a low threshold (3), so that large subvolume tree drop at mount time won't cause huge qgroup workload. CC: stable@vger.kernel.org # 6.1 Signed-off-by: Qu Wenruo Reviewed-by: David Sterba Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman Signed-off-by: Manuel Diewald Signed-off-by: Stefan Bader --- fs/btrfs/disk-io.c | 2 +- fs/btrfs/qgroup.c | 2 +- fs/btrfs/qgroup.h | 2 ++ 3 files changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index b7aa04c15984..c1eb42ff1910 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1967,7 +1967,7 @@ static void btrfs_init_qgroup(struct btrfs_fs_info *fs_info) fs_info->qgroup_seq = 1; fs_info->qgroup_ulist = NULL; fs_info->qgroup_rescan_running = false; - fs_info->qgroup_drop_subtree_thres = BTRFS_MAX_LEVEL; + fs_info->qgroup_drop_subtree_thres = BTRFS_QGROUP_DROP_SUBTREE_THRES_DEFAULT; mutex_init(&fs_info->qgroup_rescan_lock); } diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index ec2202b4bb17..b8cc28dc7c3a 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -1422,7 +1422,7 @@ int btrfs_quota_disable(struct btrfs_fs_info *fs_info) fs_info->quota_root = NULL; fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_ON; fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE; - fs_info->qgroup_drop_subtree_thres = BTRFS_MAX_LEVEL; + fs_info->qgroup_drop_subtree_thres = BTRFS_QGROUP_DROP_SUBTREE_THRES_DEFAULT; spin_unlock(&fs_info->qgroup_lock); btrfs_free_qgroup_config(fs_info); diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h index 45a7d8920d03..d46eba5b61d3 100644 --- a/fs/btrfs/qgroup.h +++ b/fs/btrfs/qgroup.h @@ -111,6 +111,8 @@ #define BTRFS_QGROUP_RUNTIME_FLAG_CANCEL_RESCAN (1ULL << 63) #define BTRFS_QGROUP_RUNTIME_FLAG_NO_ACCOUNTING (1ULL << 62) +#define BTRFS_QGROUP_DROP_SUBTREE_THRES_DEFAULT (3) + /* * Record a dirty extent, and info qgroup to update quota on it * TODO: Use kmem cache to alloc it.