> If qgroup tracking is out of sync, a rescan operation can be started. It
> iterates the complete extent tree and recalculates all qgroup tracking data.
> This is an expensive operation and should not be used unless required.
>
> A filesystem under rescan can still be umounted. The rescan continues on the
> next mount. Status information is provided with a separate ioctl while a
> rescan operation is in progress.
>
> Signed-off-by: Jan Schmidt <list.bt...@jan-o-sch.net>
Now it looks good to me.
Reviewed-by: Wang Shilong <wangsl-f...@cn.fujitsu.com>
Thanks,
Wang
> ---
> fs/btrfs/ctree.h | 17 ++-
> fs/btrfs/disk-io.c | 5 +
> fs/btrfs/ioctl.c | 83 ++++++++++--
> fs/btrfs/qgroup.c | 318
> ++++++++++++++++++++++++++++++++++++++++++--
> include/uapi/linux/btrfs.h | 12 ++-
> 5 files changed, 400 insertions(+), 35 deletions(-)
>
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 412c306..e4f28a6 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -1021,9 +1021,9 @@ struct btrfs_block_group_item {
> */
> #define BTRFS_QGROUP_STATUS_FLAG_ON (1ULL << 0)
> /*
> - * SCANNING is set during the initialization phase
> + * RESCAN is set during the initialization phase
> */
> -#define BTRFS_QGROUP_STATUS_FLAG_SCANNING (1ULL << 1)
> +#define BTRFS_QGROUP_STATUS_FLAG_RESCAN (1ULL << 1)
> /*
> * Some qgroup entries are known to be out of date,
> * either because the configuration has changed in a way that
> @@ -1052,7 +1052,7 @@ struct btrfs_qgroup_status_item {
> * only used during scanning to record the progress
> * of the scan. It contains a logical address
> */
> - __le64 scan;
> + __le64 rescan;
> } __attribute__ ((__packed__));
>
> struct btrfs_qgroup_info_item {
> @@ -1603,6 +1603,11 @@ struct btrfs_fs_info {
> /* used by btrfs_qgroup_record_ref for an efficient tree traversal */
> u64 qgroup_seq;
>
> + /* qgroup rescan items */
> + struct mutex qgroup_rescan_lock; /* protects the progress item */
> + struct btrfs_key qgroup_rescan_progress;
> + struct btrfs_workers qgroup_rescan_workers;
> +
> /* filesystem state */
> unsigned long fs_state;
>
> @@ -2888,8 +2893,8 @@ BTRFS_SETGET_FUNCS(qgroup_status_version, struct
> btrfs_qgroup_status_item,
> version, 64);
> BTRFS_SETGET_FUNCS(qgroup_status_flags, struct btrfs_qgroup_status_item,
> flags, 64);
> -BTRFS_SETGET_FUNCS(qgroup_status_scan, struct btrfs_qgroup_status_item,
> - scan, 64);
> +BTRFS_SETGET_FUNCS(qgroup_status_rescan, struct btrfs_qgroup_status_item,
> + rescan, 64);
>
> /* btrfs_qgroup_info_item */
> BTRFS_SETGET_FUNCS(qgroup_info_generation, struct btrfs_qgroup_info_item,
> @@ -3834,7 +3839,7 @@ 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_rescan(struct btrfs_fs_info *fs_info);
> +int btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info);
> int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
> struct btrfs_fs_info *fs_info, u64 src, u64 dst);
> int btrfs_del_qgroup_relation(struct btrfs_trans_handle *trans,
> diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c
> index 7717363..63e9348 100644
> --- a/fs/btrfs/disk-io.c
> +++ b/fs/btrfs/disk-io.c
> @@ -2010,6 +2010,7 @@ static void btrfs_stop_all_workers(struct btrfs_fs_info
> *fs_info)
> btrfs_stop_workers(&fs_info->caching_workers);
> btrfs_stop_workers(&fs_info->readahead_workers);
> btrfs_stop_workers(&fs_info->flush_workers);
> + btrfs_stop_workers(&fs_info->qgroup_rescan_workers);
> }
>
> /* helper to cleanup tree roots */
> @@ -2301,6 +2302,7 @@ int open_ctree(struct super_block *sb,
> fs_info->qgroup_seq = 1;
> fs_info->quota_enabled = 0;
> fs_info->pending_quota_state = 0;
> + mutex_init(&fs_info->qgroup_rescan_lock);
>
> btrfs_init_free_cluster(&fs_info->meta_alloc_cluster);
> btrfs_init_free_cluster(&fs_info->data_alloc_cluster);
> @@ -2529,6 +2531,8 @@ int open_ctree(struct super_block *sb,
> btrfs_init_workers(&fs_info->readahead_workers, "readahead",
> fs_info->thread_pool_size,
> &fs_info->generic_worker);
> + btrfs_init_workers(&fs_info->qgroup_rescan_workers, "qgroup-rescan", 1,
> + &fs_info->generic_worker);
>
> /*
> * endios are largely parallel and should have a very
> @@ -2563,6 +2567,7 @@ int open_ctree(struct super_block *sb,
> ret |= btrfs_start_workers(&fs_info->caching_workers);
> ret |= btrfs_start_workers(&fs_info->readahead_workers);
> ret |= btrfs_start_workers(&fs_info->flush_workers);
> + ret |= btrfs_start_workers(&fs_info->qgroup_rescan_workers);
> if (ret) {
> err = -ENOMEM;
> goto fail_sb_buffer;
> diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
> index d0af96a..5e93bb8 100644
> --- a/fs/btrfs/ioctl.c
> +++ b/fs/btrfs/ioctl.c
> @@ -3701,12 +3701,10 @@ static long btrfs_ioctl_quota_ctl(struct file *file,
> void __user *arg)
> }
>
> down_write(&root->fs_info->subvol_sem);
> - if (sa->cmd != BTRFS_QUOTA_CTL_RESCAN) {
> - trans = btrfs_start_transaction(root->fs_info->tree_root, 2);
> - if (IS_ERR(trans)) {
> - ret = PTR_ERR(trans);
> - goto out;
> - }
> + trans = btrfs_start_transaction(root->fs_info->tree_root, 2);
> + if (IS_ERR(trans)) {
> + ret = PTR_ERR(trans);
> + goto out;
> }
>
> switch (sa->cmd) {
> @@ -3716,9 +3714,6 @@ static long btrfs_ioctl_quota_ctl(struct file *file,
> void __user *arg)
> case BTRFS_QUOTA_CTL_DISABLE:
> ret = btrfs_quota_disable(trans, root->fs_info);
> break;
> - case BTRFS_QUOTA_CTL_RESCAN:
> - ret = btrfs_quota_rescan(root->fs_info);
> - break;
> default:
> ret = -EINVAL;
> break;
> @@ -3727,11 +3722,9 @@ static long btrfs_ioctl_quota_ctl(struct file *file,
> void __user *arg)
> if (copy_to_user(arg, sa, sizeof(*sa)))
> ret = -EFAULT;
>
> - if (trans) {
> - err = btrfs_commit_transaction(trans, root->fs_info->tree_root);
> - if (err && !ret)
> - ret = err;
> - }
> + err = btrfs_commit_transaction(trans, root->fs_info->tree_root);
> + if (err && !ret)
> + ret = err;
> out:
> kfree(sa);
> up_write(&root->fs_info->subvol_sem);
> @@ -3886,6 +3879,64 @@ drop_write:
> return ret;
> }
>
> +static long btrfs_ioctl_quota_rescan(struct file *file, void __user *arg)
> +{
> + struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
> + struct btrfs_ioctl_quota_rescan_args *qsa;
> + int ret;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> +
> + ret = mnt_want_write_file(file);
> + if (ret)
> + return ret;
> +
> + qsa = memdup_user(arg, sizeof(*qsa));
> + if (IS_ERR(qsa)) {
> + ret = PTR_ERR(qsa);
> + goto drop_write;
> + }
> +
> + if (qsa->flags) {
> + ret = -EINVAL;
> + goto out;
> + }
> +
> + ret = btrfs_qgroup_rescan(root->fs_info);
> +
> +out:
> + kfree(qsa);
> +drop_write:
> + mnt_drop_write_file(file);
> + return ret;
> +}
> +
> +static long btrfs_ioctl_quota_rescan_status(struct file *file, void __user
> *arg)
> +{
> + struct btrfs_root *root = BTRFS_I(fdentry(file)->d_inode)->root;
> + struct btrfs_ioctl_quota_rescan_args *qsa;
> + int ret = 0;
> +
> + if (!capable(CAP_SYS_ADMIN))
> + return -EPERM;
> +
> + qsa = kzalloc(sizeof(*qsa), GFP_NOFS);
> + if (!qsa)
> + return -ENOMEM;
> +
> + if (root->fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
> + qsa->flags = 1;
> + qsa->progress = root->fs_info->qgroup_rescan_progress.objectid;
> + }
> +
> + if (copy_to_user(arg, qsa, sizeof(*qsa)))
> + ret = -EFAULT;
> +
> + kfree(qsa);
> + return ret;
> +}
> +
> static long btrfs_ioctl_set_received_subvol(struct file *file,
> void __user *arg)
> {
> @@ -4124,6 +4175,10 @@ long btrfs_ioctl(struct file *file, unsigned int
> return btrfs_ioctl_qgroup_create(file, argp);
> case BTRFS_IOC_QGROUP_LIMIT:
> return btrfs_ioctl_qgroup_limit(file, argp);
> + case BTRFS_IOC_QUOTA_RESCAN:
> + return btrfs_ioctl_quota_rescan(file, argp);
> + case BTRFS_IOC_QUOTA_RESCAN_STATUS:
> + return btrfs_ioctl_quota_rescan_status(file, argp);
> case BTRFS_IOC_DEV_REPLACE:
> return btrfs_ioctl_dev_replace(root, argp);
> case BTRFS_IOC_GET_FSLABEL:
> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
> index c50e5a5..664d457 100644
> --- a/fs/btrfs/qgroup.c
> +++ b/fs/btrfs/qgroup.c
> @@ -31,13 +31,13 @@
> #include "locking.h"
> #include "ulist.h"
> #include "backref.h"
> +#include "extent_io.h"
>
> /* TODO XXX FIXME
> * - subvol delete -> delete when ref goes to 0? delete limits also?
> * - reorganize keys
> * - compressed
> * - sync
> - * - rescan
> * - copy also limits on subvol creation
> * - limit
> * - caches fuer ulists
> @@ -98,6 +98,14 @@ struct btrfs_qgroup_list {
> struct btrfs_qgroup *member;
> };
>
> +struct qgroup_rescan {
> + struct btrfs_work work;
> + struct btrfs_fs_info *fs_info;
> +};
> +
> +static void qgroup_rescan_start(struct btrfs_fs_info *fs_info,
> + struct qgroup_rescan *qscan);
> +
> /* must be called with qgroup_ioctl_lock held */
> static struct btrfs_qgroup *find_qgroup_rb(struct btrfs_fs_info *fs_info,
> u64 qgroupid)
> @@ -298,7 +306,20 @@ int btrfs_read_qgroup_config(struct btrfs_fs_info
> *fs_info)
> }
> fs_info->qgroup_flags = btrfs_qgroup_status_flags(l,
> ptr);
> - /* FIXME read scan element */
> + fs_info->qgroup_rescan_progress.objectid =
> + btrfs_qgroup_status_rescan(l, ptr);
> + if (fs_info->qgroup_flags &
> + BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
> + struct qgroup_rescan *qscan =
> + kmalloc(sizeof(*qscan), GFP_NOFS);
> + if (!qscan) {
> + ret = -ENOMEM;
> + goto out;
> + }
> + fs_info->qgroup_rescan_progress.type = 0;
> + fs_info->qgroup_rescan_progress.offset = 0;
> + qgroup_rescan_start(fs_info, qscan);
> + }
> goto next1;
> }
>
> @@ -719,7 +740,8 @@ static int update_qgroup_status_item(struct
> btrfs_trans_handle *trans,
> ptr = btrfs_item_ptr(l, slot, struct btrfs_qgroup_status_item);
> btrfs_set_qgroup_status_flags(l, ptr, fs_info->qgroup_flags);
> btrfs_set_qgroup_status_generation(l, ptr, trans->transid);
> - /* XXX scan */
> + btrfs_set_qgroup_status_rescan(l, ptr,
> + fs_info->qgroup_rescan_progress.objectid);
>
> btrfs_mark_buffer_dirty(l);
>
> @@ -830,7 +852,7 @@ int btrfs_quota_enable(struct btrfs_trans_handle *trans,
> fs_info->qgroup_flags = BTRFS_QGROUP_STATUS_FLAG_ON |
> BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
> btrfs_set_qgroup_status_flags(leaf, ptr, fs_info->qgroup_flags);
> - btrfs_set_qgroup_status_scan(leaf, ptr, 0);
> + btrfs_set_qgroup_status_rescan(leaf, ptr, 0);
>
> btrfs_mark_buffer_dirty(leaf);
>
> @@ -944,10 +966,11 @@ out:
> return ret;
> }
>
> -int btrfs_quota_rescan(struct btrfs_fs_info *fs_info)
> +static void qgroup_dirty(struct btrfs_fs_info *fs_info,
> + struct btrfs_qgroup *qgroup)
> {
> - /* FIXME */
> - return 0;
> + if (list_empty(&qgroup->dirty))
> + list_add(&qgroup->dirty, &fs_info->dirty_qgroups);
> }
>
> int btrfs_add_qgroup_relation(struct btrfs_trans_handle *trans,
> @@ -1155,13 +1178,6 @@ out:
> return ret;
> }
>
> -static void qgroup_dirty(struct btrfs_fs_info *fs_info,
> - struct btrfs_qgroup *qgroup)
> -{
> - if (list_empty(&qgroup->dirty))
> - list_add(&qgroup->dirty, &fs_info->dirty_qgroups);
> -}
> -
> /*
> * btrfs_qgroup_record_ref is called when the ref is added or deleted. it
> puts
> * the modification into a list that's later used by btrfs_end_transaction to
> @@ -1388,6 +1404,15 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle
> *trans,
> BUG();
> }
>
> + mutex_lock(&fs_info->qgroup_rescan_lock);
> + if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
> + if (fs_info->qgroup_rescan_progress.objectid <= node->bytenr) {
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> + return 0;
> + }
> + }
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> +
> /*
> * the delayed ref sequence number we pass depends on the direction of
> * the operation. for add operations, we pass (node->seq - 1) to skip
> @@ -1401,7 +1426,15 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle
> *trans,
> if (ret < 0)
> return ret;
>
> + mutex_lock(&fs_info->qgroup_rescan_lock);
> spin_lock(&fs_info->qgroup_lock);
> + if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN) {
> + if (fs_info->qgroup_rescan_progress.objectid <= node->bytenr) {
> + ret = 0;
> + goto unlock;
> + }
> + }
> +
> quota_root = fs_info->quota_root;
> if (!quota_root)
> goto unlock;
> @@ -1443,6 +1476,7 @@ int btrfs_qgroup_account_ref(struct btrfs_trans_handle
> *trans,
>
> unlock:
> spin_unlock(&fs_info->qgroup_lock);
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> ulist_free(roots);
> ulist_free(tmp);
>
> @@ -1820,3 +1854,259 @@ void assert_qgroups_uptodate(struct
> btrfs_trans_handle *trans)
> trans->delayed_ref_elem.seq);
> BUG();
> }
> +
> +/*
> + * returns < 0 on error, 0 when more leafs are to be scanned.
> + * returns 1 when done, 2 when done and FLAG_INCONSISTENT was cleared.
> + */
> +static int
> +qgroup_rescan_leaf(struct qgroup_rescan *qscan, struct btrfs_path *path,
> + struct btrfs_trans_handle *trans, struct ulist *tmp,
> + struct extent_buffer *scratch_leaf)
> +{
> + struct btrfs_key found;
> + struct btrfs_fs_info *fs_info = qscan->fs_info;
> + struct ulist *roots = NULL;
> + struct ulist_node *unode;
> + struct ulist_iterator uiter;
> + struct seq_list tree_mod_seq_elem = {};
> + u64 seq;
> + int slot;
> + int ret;
> +
> + path->leave_spinning = 1;
> + mutex_lock(&fs_info->qgroup_rescan_lock);
> + ret = btrfs_search_slot_for_read(fs_info->extent_root,
> + &fs_info->qgroup_rescan_progress,
> + path, 1, 0);
> +
> + pr_debug("current progress key (%llu %u %llu), search_slot ret %d\n",
> + (unsigned long long)fs_info->qgroup_rescan_progress.objectid,
> + fs_info->qgroup_rescan_progress.type,
> + (unsigned long long)fs_info->qgroup_rescan_progress.offset,
> + ret);
> +
> + if (ret) {
> + /*
> + * The rescan is about to end, we will not be scanning any
> + * further blocks. We cannot unset the RESCAN flag here, because
> + * we want to commit the transaction if everything went well.
> + * To make the live accounting work in this phase, we set our
> + * scan progress pointer such that every real extent objectid
> + * will be smaller.
> + */
> + fs_info->qgroup_rescan_progress.objectid = (u64)-1;
> + btrfs_release_path(path);
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> + return ret;
> + }
> +
> + btrfs_item_key_to_cpu(path->nodes[0], &found,
> + btrfs_header_nritems(path->nodes[0]) - 1);
> + fs_info->qgroup_rescan_progress.objectid = found.objectid + 1;
> +
> + btrfs_get_tree_mod_seq(fs_info, &tree_mod_seq_elem);
> + memcpy(scratch_leaf, path->nodes[0], sizeof(*scratch_leaf));
> + slot = path->slots[0];
> + btrfs_release_path(path);
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> +
> + for (; slot < btrfs_header_nritems(scratch_leaf); ++slot) {
> + btrfs_item_key_to_cpu(scratch_leaf, &found, slot);
> + if (found.type != BTRFS_EXTENT_ITEM_KEY)
> + continue;
> + ret = btrfs_find_all_roots(trans, fs_info, found.objectid,
> + tree_mod_seq_elem.seq, &roots);
> + if (ret < 0)
> + goto out;
> + spin_lock(&fs_info->qgroup_lock);
> + seq = fs_info->qgroup_seq;
> + fs_info->qgroup_seq += roots->nnodes + 1; /* max refcnt */
> +
> + ret = qgroup_account_ref_step1(fs_info, roots, tmp, seq);
> + if (ret) {
> + spin_unlock(&fs_info->qgroup_lock);
> + ulist_free(roots);
> + goto out;
> + }
> +
> + /*
> + * step2 of btrfs_qgroup_account_ref works from a single root,
> + * we're doing all at once here.
> + */
> + ulist_reinit(tmp);
> + ULIST_ITER_INIT(&uiter);
> + while ((unode = ulist_next(roots, &uiter))) {
> + struct btrfs_qgroup *qg;
> +
> + qg = find_qgroup_rb(fs_info, unode->val);
> + if (!qg)
> + continue;
> +
> + ret = ulist_add(tmp, qg->qgroupid, (uintptr_t)qg,
> + GFP_ATOMIC);
> + if (ret < 0) {
> + spin_unlock(&fs_info->qgroup_lock);
> + ulist_free(roots);
> + goto out;
> + }
> + }
> +
> + /* this loop is similar to step 2 of btrfs_qgroup_account_ref */
> + ULIST_ITER_INIT(&uiter);
> + while ((unode = ulist_next(tmp, &uiter))) {
> + struct btrfs_qgroup *qg;
> + struct btrfs_qgroup_list *glist;
> +
> + qg = (struct btrfs_qgroup *)(uintptr_t) unode->aux;
> + qg->rfer += found.offset;
> + qg->rfer_cmpr += found.offset;
> + WARN_ON(qg->tag >= seq);
> + if (qg->refcnt - seq == roots->nnodes) {
> + qg->excl += found.offset;
> + qg->excl_cmpr += found.offset;
> + }
> + qgroup_dirty(fs_info, qg);
> +
> + list_for_each_entry(glist, &qg->groups, next_group) {
> + ret = ulist_add(tmp, glist->group->qgroupid,
> + (uintptr_t)glist->group,
> + GFP_ATOMIC);
> + if (ret < 0) {
> + spin_unlock(&fs_info->qgroup_lock);
> + ulist_free(roots);
> + goto out;
> + }
> + }
> + }
> +
> + spin_unlock(&fs_info->qgroup_lock);
> + ulist_free(roots);
> + ret = 0;
> + }
> +
> +out:
> + btrfs_put_tree_mod_seq(fs_info, &tree_mod_seq_elem);
> +
> + return ret;
> +}
> +
> +static void btrfs_qgroup_rescan_worker(struct btrfs_work *work)
> +{
> + struct qgroup_rescan *qscan = container_of(work, struct qgroup_rescan,
> + work);
> + struct btrfs_path *path;
> + struct btrfs_trans_handle *trans = NULL;
> + struct btrfs_fs_info *fs_info = qscan->fs_info;
> + struct ulist *tmp = NULL;
> + struct extent_buffer *scratch_leaf = NULL;
> + int err = -ENOMEM;
> +
> + path = btrfs_alloc_path();
> + if (!path)
> + goto out;
> + tmp = ulist_alloc(GFP_NOFS);
> + if (!tmp)
> + goto out;
> + scratch_leaf = kmalloc(sizeof(*scratch_leaf), GFP_NOFS);
> + if (!scratch_leaf)
> + goto out;
> +
> + err = 0;
> + while (!err) {
> + trans = btrfs_start_transaction(fs_info->fs_root, 0);
> + if (IS_ERR(trans)) {
> + err = PTR_ERR(trans);
> + break;
> + }
> + if (!fs_info->quota_enabled) {
> + err = -EINTR;
> + } else {
> + err = qgroup_rescan_leaf(qscan, path, trans,
> + tmp, scratch_leaf);
> + }
> + if (err > 0)
> + btrfs_commit_transaction(trans, fs_info->fs_root);
> + else
> + btrfs_end_transaction(trans, fs_info->fs_root);
> + }
> +
> +out:
> + kfree(scratch_leaf);
> + ulist_free(tmp);
> + btrfs_free_path(path);
> + kfree(qscan);
> +
> + mutex_lock(&fs_info->qgroup_rescan_lock);
> + fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_RESCAN;
> +
> + if (err == 2 &&
> + fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT) {
> + fs_info->qgroup_flags &= ~BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
> + } else if (err < 0) {
> + fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT;
> + }
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> +
> + if (err >= 0) {
> + pr_info("btrfs: qgroup scan completed%s\n",
> + err == 2 ? " (inconsistency flag cleared)" : "");
> + } else {
> + pr_err("btrfs: qgroup scan failed with %d\n", err);
> + }
> +}
> +
> +static void
> +qgroup_rescan_start(struct btrfs_fs_info *fs_info, struct qgroup_rescan
> *qscan)
> +{
> + memset(&qscan->work, 0, sizeof(qscan->work));
> + qscan->work.func = btrfs_qgroup_rescan_worker;
> + qscan->fs_info = fs_info;
> +
> + pr_info("btrfs: qgroup scan started\n");
> + btrfs_queue_worker(&fs_info->qgroup_rescan_workers, &qscan->work);
> +}
> +
> +int
> +btrfs_qgroup_rescan(struct btrfs_fs_info *fs_info)
> +{
> + int ret = 0;
> + struct rb_node *n;
> + struct btrfs_qgroup *qgroup;
> + struct qgroup_rescan *qscan = kmalloc(sizeof(*qscan), GFP_NOFS);
> +
> + if (!qscan)
> + return -ENOMEM;
> +
> + mutex_lock(&fs_info->qgroup_rescan_lock);
> + spin_lock(&fs_info->qgroup_lock);
> + if (fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_RESCAN)
> + ret = -EINPROGRESS;
> + else if (!(fs_info->qgroup_flags & BTRFS_QGROUP_STATUS_FLAG_ON))
> + ret = -EINVAL;
> + if (ret) {
> + spin_unlock(&fs_info->qgroup_lock);
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> + kfree(qscan);
> + return ret;
> + }
> +
> + fs_info->qgroup_flags |= BTRFS_QGROUP_STATUS_FLAG_RESCAN;
> + memset(&fs_info->qgroup_rescan_progress, 0,
> + sizeof(fs_info->qgroup_rescan_progress));
> +
> + /* clear all current qgroup tracking information */
> + for (n = rb_first(&fs_info->qgroup_tree); n; n = rb_next(n)) {
> + qgroup = rb_entry(n, struct btrfs_qgroup, node);
> + qgroup->rfer = 0;
> + qgroup->rfer_cmpr = 0;
> + qgroup->excl = 0;
> + qgroup->excl_cmpr = 0;
> + }
> + spin_unlock(&fs_info->qgroup_lock);
> + mutex_unlock(&fs_info->qgroup_rescan_lock);
> +
> + qgroup_rescan_start(fs_info, qscan);
> +
> + return 0;
> +}
> diff --git a/include/uapi/linux/btrfs.h b/include/uapi/linux/btrfs.h
> index 5e39e85..5ef0df5 100644
> --- a/include/uapi/linux/btrfs.h
> +++ b/include/uapi/linux/btrfs.h
> @@ -376,12 +376,18 @@ struct btrfs_ioctl_get_dev_stats {
>
> #define BTRFS_QUOTA_CTL_ENABLE 1
> #define BTRFS_QUOTA_CTL_DISABLE 2
> -#define BTRFS_QUOTA_CTL_RESCAN 3
> +#define BTRFS_QUOTA_CTL_RESCAN__NOTUSED 3
> struct btrfs_ioctl_quota_ctl_args {
> __u64 cmd;
> __u64 status;
> };
>
> +struct btrfs_ioctl_quota_rescan_args {
> + __u64 flags;
> + __u64 progress;
> + __u64 reserved[6];
> +};
> +
> struct btrfs_ioctl_qgroup_assign_args {
> __u64 assign;
> __u64 src;
> @@ -520,6 +526,10 @@ struct btrfs_ioctl_send_args {
> struct btrfs_ioctl_qgroup_create_args)
> #define BTRFS_IOC_QGROUP_LIMIT _IOR(BTRFS_IOCTL_MAGIC, 43, \
> struct btrfs_ioctl_qgroup_limit_args)
> +#define BTRFS_IOC_QUOTA_RESCAN _IOW(BTRFS_IOCTL_MAGIC, 44, \
> + struct btrfs_ioctl_quota_rescan_args)
> +#define BTRFS_IOC_QUOTA_RESCAN_STATUS _IOR(BTRFS_IOCTL_MAGIC, 45, \
> + struct btrfs_ioctl_quota_rescan_args)
> #define BTRFS_IOC_GET_FSLABEL _IOR(BTRFS_IOCTL_MAGIC, 49, \
> char[BTRFS_LABEL_SIZE])
> #define BTRFS_IOC_SET_FSLABEL _IOW(BTRFS_IOCTL_MAGIC, 50, \
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