On 09/21/2015 05:44 PM, Jan Kara wrote:
On Mon 21-09-15 17:16:49, Dongsheng Yang wrote:
On 09/21/2015 05:13 PM, Jan Kara wrote:
On Mon 21-09-15 12:35:01, Dongsheng Yang wrote:
On 09/18/2015 07:20 PM, Jan Kara wrote:
.... TBH, there is a little different with other filesystems. I did not
use the "disk" space, but the file space in ubifs quota, although dquot
means disk quota. Same with btrfs quota. If we use disk space for quota,
the most common problem from user is that: why I did not reach the limit
but I can not write any byte. COW in btrfs or out-place-updating in
ubifs makes this problem much worse.
So I choose file space here for ubifs.
OK, so these are really two separate questions. I understand your choice of
using file space as the amount of space to account for quota purposes and
I'm fine with that choice. Another thing is that regardless of how you
decide to do quota accounting, you must maintain i_blocks / i_bytes to
contain proper value because dquot_transfer() uses that information to update
quota usage when inode owner is changed.
But if we don't use i_blocks to get qsize, what we care only in
dquot_transter() is dquot->dq_dqb. That means, even if the i_blocks
is not correct in dquot_transfer() in ubifs, that's okey, because we
will never use this value, right?
dquot_transfer() will use the value - when file F changes owner from user A
to user B, then you need to decrement amount of space used by F from A's
quota usage and add that amount to B's quota usage. And the amount of space
is obtained via inode_get_bytes() which uses i_blocks and i_bytes. See
__dquot_transfer() in fs/quota/dquot.c for details.
Yes, I see it. But if ubifs doesn't use i_blocks and i_bytes to stand
for quota size, as I mentioned I want to use i_size. Then we will never
use i_blocks. So we only need a to transfer dquot->dq_dqb values. That
means, even the i_blocks in dquot_transfer() is not correct, we don't
care it. we only need to make sure values in dquot_dq_dqb are
transfered, such as dquot->dq_dqb->curspace for user B is equal with
i_size.
I think you are missing one thing:
Assume user A has files F1 (1MB) F2 (2MB) F3 (3MB).
User B has one file G1 (4MB).
So user A uses 6 MB in total (stored in dquot for user A in dqb_curspace
field). User B uses 4MB.
Now you do "chown B F1"
You need to change dq_dqb of F1 to point to user B quota structure as you
explain, that is correct. However you also need to subtract 1MB from user
A's total usage (which is stored in struct dquot for user A) since file F1
no longer belongs to him. And you need to add 1 MB to user B's total usage.
After this user A will have total usage of 5 MB and user B has usage of 5
MB as well. You need to properly update the total usage of each user so
that you can check the usage against quota limits.
But that's all done in dquot_transfer(). It dquot_decr_space(from) and
dquot_incr_space(to). Let me show the test result in my implementation.
(1). root -> 1M/2M/3M yds ->4M
[root@atest-guest linux_compile]# ll -h /mnt/ubifs/
total 11M
-rw-r--r--. 1 root root 1.0M Sep 21 15:54 1M
-rw-r--r--. 1 root root 2.0M Sep 21 15:54 2M
-rw-r--r--. 1 root root 3.0M Sep 21 15:54 3M
-rw-r--r--. 1 yds root 4.0M Sep 21 15:55 4M
-rw-------. 1 root root 6.0K Sep 21 15:53 aquota.group
-rw-------. 1 root root 7.0K Sep 21 15:53 aquota.user
[root@atest-guest linux_compile]# repquota -u /mnt/ubifs/
*** Report for user quotas on device /dev/ubi0_0
Block grace time: 7days; Inode grace time: 7days
Block limits File limits
User used soft hard grace used soft hard grace
----------------------------------------------------------------------
root -- 6144 0 0 4 0 0
yds -- 4096 0 0 1 0 0
(2). chown yds /mnt/ubifs/1M
[root@atest-guest linux_compile]# chown yds /mnt/ubifs/1M
[root@atest-guest linux_compile]# ll -h /mnt/ubifs/
total 11M
-rw-r--r--. 1 yds root 1.0M Sep 21 15:54 1M
-rw-r--r--. 1 root root 2.0M Sep 21 15:54 2M
-rw-r--r--. 1 root root 3.0M Sep 21 15:54 3M
-rw-r--r--. 1 yds root 4.0M Sep 21 15:55 4M
-rw-------. 1 root root 6.0K Sep 21 15:53 aquota.group
-rw-------. 1 root root 7.0K Sep 21 15:53 aquota.user
[root@atest-guest linux_compile]# repquota -u /mnt/ubifs/
*** Report for user quotas on device /dev/ubi0_0
Block grace time: 7days; Inode grace time: 7days
Block limits File limits
User used soft hard grace used soft hard grace
----------------------------------------------------------------------
root -- 5120 0 0 3 0 0
yds -- 5120 0 0 2 0 0
(3). quotacheck and check again.
[root@atest-guest linux_compile]# quotaoff /mnt/ubifs && quotacheck -u
/mnt/ubifs/
[root@atest-guest linux_compile]# ll -h /mnt/ubifs
total 11M
-rw-r--r--. 1 yds root 1.0M Sep 21 15:54 1M
-rw-r--r--. 1 root root 2.0M Sep 21 15:54 2M
-rw-r--r--. 1 root root 3.0M Sep 21 15:54 3M
-rw-r--r--. 1 yds root 4.0M Sep 21 15:55 4M
-rw-------. 1 root root 6.0K Sep 21 15:53 aquota.group
-rw-------. 1 root root 7.0K Sep 21 16:00 aquota.user
[root@atest-guest linux_compile]# repquota -u /mnt/ubifs/
*** Report for user quotas on device /dev/ubi0_0
Block grace time: 7days; Inode grace time: 7days
Block limits File limits
User used soft hard grace used soft hard grace
----------------------------------------------------------------------
root -- 5120 0 0 3 0 0
yds -- 5120 0 0 2 0 0
Yang
Honza
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