quota: fix a problem about transfer quota

Run below script as root, dquot_add_space will return -EDQUOT since
__dquot_transfer call dquot_add_space with flags=0, and dquot_add_space
think it's a preallocation. Fix it by set flags as DQUOT_SPACE_WARN.

mkfs.ext4 -O quota,project /dev/vdb
mount -o prjquota /dev/vdb /mnt
setquota -P 23 1 1 0 0 /dev/vdb
dd if=/dev/zero of=/mnt/test-file bs=4K count=1
chattr -p 23 test-file

Fixes: 7b9ca4c6 ("quota: Reduce contention on dq_data_lock")
Signed-off-by: yangerkun <yangerkun@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>

fs/quota/dquot.c

@@ -1996,8 +1996,8 @@ int __dquot_transfer(struct inode *inode, struct dquot **transfer_to)
 				       &warn_to[cnt]);
 		if (ret)
 			goto over_quota;
-		ret = dquot_add_space(transfer_to[cnt], cur_space, rsv_space, 0,
-				      &warn_to[cnt]);
+		ret = dquot_add_space(transfer_to[cnt], cur_space, rsv_space,
+				      DQUOT_SPACE_WARN, &warn_to[cnt]);
 		if (ret) {
 			spin_lock(&transfer_to[cnt]->dq_dqb_lock);
 			dquot_decr_inodes(transfer_to[cnt], inode_usage);