| Message ID | 51889BF1.1000300@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, May 07, 2013 at 08:15 (+0200), Wang Shilong wrote: > If qgroup_rescan worker is in progress, we should ignore > the extent that has not been dealt with qgroup_rescan worker,just > let them dealt later otherwise we may get wrong qgroup accounting. > > However, we have checked this before find_all_roots() without spin_lock. > When doing qgroup accounting, we don't have to check it again, because > during this period,qgroup_rescan worker can deal with more extents and > qgroup_rescan_extent->objectid can only go larger, so here the check > is unnecessary. > > Just remove this check, so that we don't need hold qgroup_rescan_lock > when doing qgroup accounting. NAK. After a discussion on that lock the last thing in this thread I see is ... On Wed, May 01, 2013 at 13:57 (+0200), Jan Schmidt wrote: > Now I see what you mean. The second check is only required when we start > a rescan operation after the initial check in btrfs_qgroup_account_ref. Please continue on that argument, your commit message doesn't explain at all why we should be safe to remove this check. -Jan > Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com> > --- > fs/btrfs/qgroup.c | 9 --------- > 1 files changed, 0 insertions(+), 9 deletions(-) > > diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c > index d059d86..2710784 100644 > --- a/fs/btrfs/qgroup.c > +++ b/fs/btrfs/qgroup.c > @@ -1445,15 +1445,7 @@ 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; > @@ -1492,7 +1484,6 @@ 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); > > return ret; > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hello Jan, > On Tue, May 07, 2013 at 08:15 (+0200), Wang Shilong wrote: >> If qgroup_rescan worker is in progress, we should ignore >> the extent that has not been dealt with qgroup_rescan worker,just >> let them dealt later otherwise we may get wrong qgroup accounting. >> >> However, we have checked this before find_all_roots() without spin_lock. >> When doing qgroup accounting, we don't have to check it again, because >> during this period,qgroup_rescan worker can deal with more extents and >> qgroup_rescan_extent->objectid can only go larger, so here the check >> is unnecessary. >> >> Just remove this check, so that we don't need hold qgroup_rescan_lock >> when doing qgroup accounting. > > NAK. > > After a discussion on that lock the last thing in this thread I see is ... > > On Wed, May 01, 2013 at 13:57 (+0200), Jan Schmidt wrote: >> Now I see what you mean. The second check is only required when we start >> a rescan operation after the initial check in btrfs_qgroup_account_ref. > > Please continue on that argument, your commit message doesn't explain at all why > we should be safe to remove this check. You are right! Thanks, Wang > > -Jan > >> Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com> >> --- >> fs/btrfs/qgroup.c | 9 --------- >> 1 files changed, 0 insertions(+), 9 deletions(-) >> >> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c >> index d059d86..2710784 100644 >> --- a/fs/btrfs/qgroup.c >> +++ b/fs/btrfs/qgroup.c >> @@ -1445,15 +1445,7 @@ 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; >> @@ -1492,7 +1484,6 @@ 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); >> >> return ret; >> > > -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c index d059d86..2710784 100644 --- a/fs/btrfs/qgroup.c +++ b/fs/btrfs/qgroup.c @@ -1445,15 +1445,7 @@ 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; @@ -1492,7 +1484,6 @@ 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); return ret;
If qgroup_rescan worker is in progress, we should ignore the extent that has not been dealt with qgroup_rescan worker,just let them dealt later otherwise we may get wrong qgroup accounting. However, we have checked this before find_all_roots() without spin_lock. When doing qgroup accounting, we don't have to check it again, because during this period,qgroup_rescan worker can deal with more extents and qgroup_rescan_extent->objectid can only go larger, so here the check is unnecessary. Just remove this check, so that we don't need hold qgroup_rescan_lock when doing qgroup accounting. Signed-off-by: Wang Shilong <wangsl-fnst@cn.fujitsu.com> --- fs/btrfs/qgroup.c | 9 --------- 1 files changed, 0 insertions(+), 9 deletions(-)