Hi Josef and Mark,
I saw the commit message of 1152651a:
[btrfs: qgroup: account shared subtrees during snapshot delete]
that SUBTREE operation was introduced to account the quota number
in subvolume deleting.
But, I found it does not work well currently：
Create subvolume '/mnt/sub'
+ btrfs qgroup show -prce /mnt
qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 16.00KiB 16.00KiB 0.00B 0.00B --- ---
0/257 16.00KiB 16.00KiB 0.00B 0.00B --- ---
+ dd if=/dev/zero of=/mnt/sub/data bs=1024 count=100
100+0 records in
100+0 records out
102400 bytes (102 kB) copied, 0.000876526 s, 117 MB/s
+ sync
+ btrfs qgroup show -prce --raw /mnt
qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 16384 16384 0 0 --- ---
0/257 118784 118784 0 0 --- ---
+ btrfs sub snap /mnt/sub /mnt/snap
Create a snapshot of '/mnt/sub' in '/mnt/snap'
+ sync
+ btrfs qgroup show -prce --raw /mnt
qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 16384 16384 0 0 --- ---
0/257 118784 16384 0 0 --- ---
0/258 118784 16384 0 0 --- ---
+ btrfs sub delete /mnt/sub
Delete subvolume (no-commit): '/mnt/sub'
+ sync
+ btrfs qgroup show -prce --raw /mnt
qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 16384 16384 0 0 --- ---
0/257 118784 16384 0 0 --- ---
0/258 118784 16384 0 0 --- ---
---------------------------------------------------------------------------
<------- WAIT for cleaner
[root@atest-guest linux_btrfs]# btrfs qgroup show -prce /mnt
qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 16.00KiB 16.00KiB 0.00B 0.00B --- ---
0/257 100.00KiB 0.00B 0.00B 0.00B --- --- <------- the data size was
not cleaned from qgroup.
0/258 116.00KiB 116.00KiB 0.00B 0.00B --- --- <------- but the excl in
the snapshot qgroup is increased to 116KB by SUBTREE operation
My question is:
(1), SUBTREE is not working well.
(2), why we need a rule-breaker in qgroup operations SUBTREE to do
this work?
We can do it via the delayed-ref routine like the other qgroup
operations.
with my patch here applied and 1152651a reverted, I got the result:
qgroupid rfer excl max_rfer max_excl parent child
-------- ---- ---- -------- -------- ------ -----
0/5 16.00KiB 16.00KiB 0.00B 0.00B --- ---
0/257 0.00B 0.00B 0.00B 0.00B --- --- <----------- data and tree block
both are cleaned
0/258 116.00KiB 116.00KiB 0.00B 0.00B --- --- <------ quota numbers in
snapshot qgroup is correct.
(1), quota is working well now in subvolume deleting.
(2), all operations are inserted by delayed-ref.
So, the conclusion seems like that:
(1), commit 1152651a was introducing a SUBTREE operation to account
the number in subvolume deleted.
(2). SUBTREE is not working well.
(3). we can solve the same problem in a better way without introducing
a new operation of SUBTREE.
To be honest, I am suspecting myself *very much*. I trust you guys and
believe there must be something I am missing.
Then I send this mail to ask your help.
Thanx in advance.
Yang
On 02/10/2015 06:24 PM, Dongsheng Yang wrote:
In function of __btrfs_mod_ref(), we are passing the no_quota=1
to process_func() anyway. It will make the numbers in qgroup be
wrong when deleting a subvolume. The data size in a deleted subvolume
will never be decressed from all related qgroups.
Signed-off-by: Dongsheng Yang <yangds.f...@cn.fujitsu.com>
---
fs/btrfs/extent-tree.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
index 652be74..f59809c 100644
--- a/fs/btrfs/extent-tree.c
+++ b/fs/btrfs/extent-tree.c
@@ -3056,6 +3056,7 @@ static int __btrfs_mod_ref(struct
btrfs_trans_handle *trans,
int i;
int level;
int ret = 0;
+ int no_quota = 0;
int (*process_func)(struct btrfs_trans_handle *, struct
btrfs_root *,
u64, u64, u64, u64, u64, u64, int);
@@ -3080,6 +3081,9 @@ static int __btrfs_mod_ref(struct
btrfs_trans_handle *trans,
else
parent = 0;
+ if (!root->fs_info->quota_enabled || !is_fstree(ref_root))
+ no_quota = 1;
+
for (i = 0; i < nritems; i++) {
if (level == 0) {
btrfs_item_key_to_cpu(buf, &key, i);
@@ -3098,7 +3102,7 @@ static int __btrfs_mod_ref(struct
btrfs_trans_handle *trans,
key.offset -= btrfs_file_extent_offset(buf, fi);
ret = process_func(trans, root, bytenr, num_bytes,
parent, ref_root, key.objectid,
- key.offset, 1);
+ key.offset, no_quota);
if (ret)
goto fail;
} else {
@@ -3106,7 +3110,7 @@ static int __btrfs_mod_ref(struct
btrfs_trans_handle *trans,
num_bytes = root->nodesize;
ret = process_func(trans, root, bytenr, num_bytes,
parent, ref_root, level - 1, 0,
- 1);
+ no_quota);
if (ret)
goto fail;
}
--
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