Hi Jan,
> Hi Wang,
>
> On 01.05.2013 09:29, Wang Shilong wrote:
>> Hello Jan,
>>
>>> 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.btrfs@xxxxxxxxxxxxx>
>>> ---
>>> 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 * Some qgroup entries are known to be out of date,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);
>>
>>
>> Why do you hold qgroup_rescan_lock when doing qgroup accounting here?
>> I can understand that we hold qgroup_rescan_lock when we update qgroup_flag(at first in qgroup_account_ref()),
>> However, is it necessary that we hold qgroup_rescan_lock when we are doing qgroup
>> accounting step1,2,3??
>>
>> Or am i missing something here?
>
> We need the lock for the check added above. This check needs the mutex
> lock, while the three accounting steps need a spin lock (which was not
> modified by my patch). We cannot call mutex_unlock while holding a spin
> lock, because mutex_unlock might schedule.
Yeah, but do we need check that again? Considering we check:
"fs_info->qgroup_rescan_progress.objectid <= node->bytenr" before find_all_roots()
is called, if we can continue, that means "objected > node->bytenr". The point is that is it
possible that "objected <= node-bytenr" after find_all_roots() when we are doing qgroup
accounting.
Here i think group_rescan_progress.objectid can only go larger, so it is not necessary to check it
again when we are doing qgroup accounting steps thus we can save qgroup_rescan_lock usage here.
What do you think of this, please correct me if i am wrong.
Thanks,
Wang
>
> Thanks,
> -Jan
>
>> Thanks,
>> Wang
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