Hello Jan,
On 10/24/2013 11:36 PM, Jan Schmidt wrote:
On Thu, October 24, 2013 at 16:49 (+0200), Wang Shilong wrote:
Hello Jan,
btrfs_dec_ref() queued a delayed ref for owner of a tree block. The qgroup
tracking is based on delayed refs. The owner of a tree block is set when a
tree block is allocated, it is never updated.
When you allocate a tree block and then remove the subvolume that did the
allocation, the qgroup accounting for that removal is correct. However, the
removal was accounted again for each subvolume deletion that also referenced
the tree block, because accounting was erroneously based on the owner.
Instead of queueing delayed refs for the non-existent owner, we now
queue delayed refs for the root being removed. This fixes the qgroup
accounting.
Thanks for tracking this, i apply your patch, and using the flowing patch,
found the problem still exist, the test script like the following:
Reproduced. Gives more negative numbers due to accounting triggered by the
cleaner thread, that's the common part here. I still believe that the fix I sent
is correct, it's probably not complete. Looking into it.
I really wait cleaner thread to finish work, and i use btrfs-debug-tree
to confirm
all the fs tree have been deleted.
But using btrfs qgroup show, i still get negative numers, also root
subvolume's
exclusive is wrong.. Statices are like following.
0/5 13090816 471040
0/257 13078528 0
0/259 13078528 0
0/260 13078528 0
0/261 13078528 0
.........................
........................
.......................
0/350 13078528 0
0/351 13078528 0
0/352 13078528 0
0/353 13078528 0
0/354 13078528 0
0/355 13078528 0
0/356 13078528 0
0/357 13078528 0
0/358 12619776 -155648
Thanks,
Wang
Thanks,
-Jan
#!/bin/sh
for i in $(seq 1000)
do
dd if=/dev/zero
of=<mnt>/$i""aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa bs=10K
count=1
done
btrfs sub snapshot <mnt> <mnt>/1
for i in $(seq 100)
do
btrfs sub snapshot <mnt>/$i <mnt>/$(($i+1))
done
for i in $(seq 101)
do
btrfs sub delete <mnt>/$i
done
Thanks,
Wang
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