Hi Qu,
On 02/19/2017 09:07 PM, Qu Wenruo wrote:
>
>
> At 02/19/2017 09:30 PM, Goldwyn Rodrigues wrote:
>> From: Goldwyn Rodrigues <[email protected]>
>>
>> We are facing the same problem with EDQUOT which was experienced with
>> ENOSPC. Not sure if we require a full ticketing system such as ENOSPC,
>> but
>> here is a fix. Let me know if it is too big a hammer.
>>
>> Quotas are reserved during the start of an operation, incrementing
>> qg->reserved. However, it is written to disk in a commit_transaction
>> which could take as long as commit_interval. In the meantime there
>> could be deletions which are not accounted for because deletions are
>> accounted for only while committed (free_refroot). So, when we get
>> a EDQUOT flush the data to disk and try again.
>
> IIRC Jeff submitted a qgroup patch to allow unlink to be done even we
> already hit EDQUOT.
> https://patchwork.kernel.org/patch/9537193/
>
> I think that's a better solution, which is quite like what we do to
> handle ENOSPC.
>
These are two separate issues. This issue is where qg->reserved gets
over-inflated because of repeated deletions and recreations within a
commit_interval.
Jeff's patch deals with allowing removal even if the quota is exceeded
so that eventually there can be space freed.
I would suggest you apply Jeff's patch and try to run the script I have
presented.
> Thanks,
> Qu
>
>>
>> I combined the conditions of rfer and excl to reduce code lines, though
>> the condition looks uglier.
>>
>> Here is a sample script which shows this issue.
>>
>> DEVICE=/dev/vdb
>> MOUNTPOINT=/mnt
>> TESTVOL=$MOUNTPOINT/tmp
>> QUOTA=5
>> PROG=btrfs
>> DD_BS="4k"
>> DD_COUNT="256"
>> RUN_TIMES=5000
>>
>> mkfs.btrfs -f $DEVICE
>> mount -o commit=240 $DEVICE $MOUNTPOINT
>> $PROG subvolume create $TESTVOL
>> $PROG quota enable $TESTVOL
>> $PROG qgroup limit ${QUOTA}G $TESTVOL
>>
>> typeset -i DD_RUN_GOOD
>> typeset -i QUOTA
>>
>> function _check_cmd() {
>> if [[ ${?} > 0 ]]; then
>> echo -n "$(date) E: Running previous command"
>> echo ${*}
>> echo "Without sync"
>> $PROG qgroup show -pcreFf ${TESTVOL}
>> echo "With sync"
>> $PROG qgroup show -pcreFf --sync ${TESTVOL}
>> exit 1
>> fi
>> }
>>
>> while true; do
>> DD_RUN_GOOD=$RUN_TIMES
>>
>> while (( ${DD_RUN_GOOD} != 0 )); do
>> dd if=/dev/zero of=${TESTVOL}/quotatest${DD_RUN_GOOD} bs=${DD_BS}
>> count=${DD_COUNT}
>> _check_cmd "dd if=/dev/zero of=${TESTVOL}/quotatest${DD_RUN_GOOD}
>> bs=${DD_BS} count=${DD_COUNT}"
>> DD_RUN_GOOD=(${DD_RUN_GOOD}-1)
>> done
>>
>> $PROG qgroup show -pcref $TESTVOL
>> echo "----------- Cleanup ---------- "
>> rm $TESTVOL/quotatest*
>>
>> done
>>
>> Signed-off-by: Goldwyn Rodrigues <[email protected]>
>> ---
>> fs/btrfs/qgroup.c | 28 +++++++++++++++++-----------
>> 1 file changed, 17 insertions(+), 11 deletions(-)
>>
>> diff --git a/fs/btrfs/qgroup.c b/fs/btrfs/qgroup.c
>> index 4700cac..9ace407 100644
>> --- a/fs/btrfs/qgroup.c
>> +++ b/fs/btrfs/qgroup.c
>> @@ -2093,6 +2093,7 @@ static int qgroup_reserve(struct btrfs_root
>> *root, u64 num_bytes)
>> struct btrfs_fs_info *fs_info = root->fs_info;
>> u64 ref_root = root->root_key.objectid;
>> int ret = 0;
>> + int retried = 0;
>> struct ulist_node *unode;
>> struct ulist_iterator uiter;
>>
>> @@ -2101,7 +2102,7 @@ static int qgroup_reserve(struct btrfs_root
>> *root, u64 num_bytes)
>>
>> if (num_bytes == 0)
>> return 0;
>> -
>> +retry:
>> spin_lock(&fs_info->qgroup_lock);
>> quota_root = fs_info->quota_root;
>> if (!quota_root)
>> @@ -2127,16 +2128,21 @@ static int qgroup_reserve(struct btrfs_root
>> *root, u64 num_bytes)
>>
>> qg = u64_to_ptr(unode->aux);
>>
>> - if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_RFER) &&
>> - qg->reserved + (s64)qg->rfer + num_bytes >
>> - qg->max_rfer) {
>> - ret = -EDQUOT;
>> - goto out;
>> - }
>> -
>> - if ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_EXCL) &&
>> - qg->reserved + (s64)qg->excl + num_bytes >
>> - qg->max_excl) {
>> + if (((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_RFER) &&
>> + qg->reserved + (s64)qg->rfer + num_bytes >
>> qg->max_rfer) ||
>> + ((qg->lim_flags & BTRFS_QGROUP_LIMIT_MAX_EXCL) &&
>> + qg->reserved + (s64)qg->excl + num_bytes > qg->max_excl)) {
>> + if (!retried && qg->reserved > 0) {
>> + struct btrfs_trans_handle *trans;
>> + spin_unlock(&fs_info->qgroup_lock);
>> + btrfs_start_delalloc_roots(fs_info, 0, -1);
>> + trans = btrfs_join_transaction(root);
>> + if (IS_ERR(trans))
>> + return PTR_ERR(trans);
>> + btrfs_commit_transaction(trans, root);
>> + retried++;
>> + goto retry;
>> + }
>> ret = -EDQUOT;
>> goto out;
>> }
>>
>
>
--
Goldwyn
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