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 * Some qgroup entries are known to be out of date,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.
Thanks,
-Jan
> Thanks,
> Wang
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