On 2018/07/02 20:00, Nikolay Borisov wrote:
> Commit 5d23515be669 ("btrfs: Move qgroup rescan on quota enable to
> btrfs_quota_enable") not only resulted in an easier to follow code but
> it also introduced a subtle bug. It changed the timing when the initial
> transaction rescan was happening - before the commit it would happen
> after transaction commit had occured but after the commit it might happen
> before the transaction was committed. This results in failure to
> correctly rescan the quota since there could be data which is still not
> committed on disk.
>
> This patch aims to fix this by movign the transaction creation/commit
> inside btrfs_quota_enable, which allows to schedule the quota commit
> after the transaction has been committed.
>
> Fixes: 5d23515be669 ("btrfs: Move qgroup rescan on quota enable to btrfs_quota_enable")
> Link: https://marc.info/?l=linux-btrfs&m=152999289017582
> Reported-by: Misono Tomohiro <misono.tomohiro@xxxxxxxxxxxxxx>
> Reviewed-by: Misono Tomohiro <misono.tomohiro@xxxxxxxxxxxxxx>
> Signed-off-by: Nikolay Borisov <nborisov@xxxxxxxx>
> ---
> fs/btrfs/ioctl.c | 15 ++-------------
> fs/btrfs/qgroup.c | 38 +++++++++++++++++++++++++++++++-------
> fs/btrfs/qgroup.h | 6 ++----
> 3 files changed, 35 insertions(+), 24 deletions(-)
>
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index a399750b9e41..316fb1af15e2 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -5135,9 +5135,7 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
> struct inode *inode = file_inode(file);
> struct btrfs_fs_info *fs_info = btrfs_sb(inode->i_sb);
> struct btrfs_ioctl_quota_ctl_args *sa;
> - struct btrfs_trans_handle *trans = NULL;
> int ret;
> - int err;
>
> if (!capable(CAP_SYS_ADMIN))
> return -EPERM;
> @@ -5153,28 +5151,19 @@ static long btrfs_ioctl_quota_ctl(struct file *file, void __user *arg)
> }
>
> down_write(&fs_info->subvol_sem);
> - trans = btrfs_start_transaction(fs_info->tree_root, 2);
> - if (IS_ERR(trans)) {
> - ret = PTR_ERR(trans);
> - goto out;
> - }
>
> switch (sa->cmd) {
> case BTRFS_QUOTA_CTL_ENABLE:
> - ret = btrfs_quota_enable(trans, fs_info);
> + ret = btrfs_quota_enable(fs_info);
> break;
> case BTRFS_QUOTA_CTL_DISABLE:
> - ret = btrfs_quota_disable(trans, fs_info);
> + ret = btrfs_quota_disable(fs_info);
> break;
> default:
> ret = -EINVAL;
> break;
> }
>
> - err = btrfs_commit_transaction(trans);
> - if (err && !ret)
> - ret = err;
> -out:
> kfree(sa);
> up_write(&fs_info->subvol_sem);
> drop_write:
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index c25dc47210a3..1012c7138633 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -875,8 +875,7 @@ static int btrfs_clean_quota_tree(struct btrfs_trans_handle *trans,
> return ret;
> }
>
> -int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> - struct btrfs_fs_info *fs_info)
> +int btrfs_quota_enable(struct btrfs_fs_info *fs_info)
> {
> struct btrfs_root *quota_root;
> struct btrfs_root *tree_root = fs_info->tree_root;
> @@ -886,6 +885,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> struct btrfs_key key;
> struct btrfs_key found_key;
> struct btrfs_qgroup *qgroup = NULL;
> + struct btrfs_trans_handle *trans = NULL;
> int ret = 0;
> int slot;
>
> @@ -893,6 +893,12 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> if (fs_info->quota_root)
> goto out;
>
> + trans = btrfs_start_transaction(tree_root, 2);
> + if (IS_ERR(trans)) {
> + ret = PTR_ERR(trans);
> + goto out;
> + }
> +
fs_info->qgroup_ulist = ulist_alloc(GFP_KERNEL);
> if (!fs_info->qgroup_ulist) {
> ret = -ENOMEM;
> @@ -987,6 +993,11 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> fs_info->quota_root = quota_root;
> set_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
> spin_unlock(&fs_info->qgroup_lock);
> +
> + ret = btrfs_commit_transaction(trans);
> + if (ret)
> + goto out_free_path;
> +
I realized that some error paths also need to finish transaction (continue to below).
> ret = qgroup_rescan_init(fs_info, 0, 1);
> if (!ret) {
> qgroup_rescan_zero_tracking(fs_info);
> @@ -1011,15 +1022,22 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> return ret;
> }
>
> -int btrfs_quota_disable(struct btrfs_trans_handle *trans,
> - struct btrfs_fs_info *fs_info)
> +int btrfs_quota_disable(struct btrfs_fs_info *fs_info)
> {
> struct btrfs_root *quota_root;
> + struct btrfs_trans_handle *trans = NULL;
> int ret = 0;
>
> mutex_lock(&fs_info->qgroup_ioctl_lock);
> if (!fs_info->quota_root)
> goto out;
> +
> + trans = btrfs_start_transaction(fs_info->tree_root, 2);
> + if (IS_ERR(trans)) {
> + ret = PTR_ERR(trans);
> + goto out;
> + }
> +
> clear_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags);
> btrfs_qgroup_wait_for_completion(fs_info, false);
> spin_lock(&fs_info->qgroup_lock);
> @@ -1031,12 +1049,16 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans,
> btrfs_free_qgroup_config(fs_info);
>
> ret = btrfs_clean_quota_tree(trans, quota_root);
> - if (ret)
> + if (ret) {
> + btrfs_abort_transaction(trans, ret);
And btrfs_end_transaction() is needed here and below.
Thanks,
Misono
> goto out;
> + }
>
> ret = btrfs_del_root(trans, fs_info, "a_root->root_key);
> - if (ret)
> + if (ret) {
> + btrfs_abort_transaction(trans, ret);
> goto out;
> + }
>
> list_del("a_root->dirty_list);
>
> @@ -1048,6 +1070,8 @@ int btrfs_quota_disable(struct btrfs_trans_handle *trans,
> free_extent_buffer(quota_root->node);
> free_extent_buffer(quota_root->commit_root);
> kfree(quota_root);
> +
> + ret = btrfs_commit_transaction(trans);
> out:
> mutex_unlock(&fs_info->qgroup_ioctl_lock);
> return ret;
> @@ -3070,7 +3094,7 @@ static int __btrfs_qgroup_release_data(struct inode *inode,
> if (free && reserved)
> return qgroup_free_reserved_data(inode, reserved, start, len);
> extent_changeset_init(&changeset);
> - ret = clear_record_extent_bits(&BTRFS_I(inode)->io_tree, start,
> + ret = clear_record_extent_bits(&BTRFS_I(inode)->io_tree, start,
> start + len -1, EXTENT_QGROUP_RESERVED, &changeset);
> if (ret < 0)
> goto out;
> diff --git a/fs/btrfs/qgroup.h b/fs/btrfs/qgroup.h
> index d60dd06445ce..bec7c9b17a8e 100644
> --- a/fs/btrfs/qgroup.h
> +++ b/fs/btrfs/qgroup.h
> @@ -141,10 +141,8 @@ struct btrfs_qgroup {
> #define QGROUP_RELEASE (1<<1)
> #define QGROUP_FREE (1<<2)
>
> -int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> - struct btrfs_fs_info *fs_info);
> -int btrfs_quota_disable(struct btrfs_trans_handle *trans,
> - struct btrfs_fs_info *fs_info);
> +int btrfs_quota_enable(struct btrfs_fs_info *fs_info);
> +int btrfs_quota_disable(struct btrfs_fs_info *fs_info);
> int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
> void btrfs_qgroup_rescan_resume(struct btrfs_fs_info *fs_info);
> int btrfs_qgroup_wait_for_completion(struct btrfs_fs_info *fs_info,
>
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