f2fs: fix to avoid inconsistent quota data

Occasionally, quota data may be corrupted detected by fsck:

Info: checkpoint state = 45 :  crc compacted_summary unmount
[QUOTA WARNING] Usage inconsistent for ID 0:actual (1543036928, 762) != expected (1543032832, 762)
[ASSERT] (fsck_chk_quota_files:1986)  --> Quota file is missing or invalid quota file content found.
[QUOTA WARNING] Usage inconsistent for ID 0:actual (1352478720, 344) != expected (1352474624, 344)
[ASSERT] (fsck_chk_quota_files:1986)  --> Quota file is missing or invalid quota file content found.

[FSCK] Unreachable nat entries                        [Ok..] [0x0]
[FSCK] SIT valid block bitmap checking                [Ok..]
[FSCK] Hard link checking for regular file            [Ok..] [0x0]
[FSCK] valid_block_count matching with CP             [Ok..] [0xdf299]
[FSCK] valid_node_count matcing with CP (de lookup)   [Ok..] [0x2b01]
[FSCK] valid_node_count matcing with CP (nat lookup)  [Ok..] [0x2b01]
[FSCK] valid_inode_count matched with CP              [Ok..] [0x2665]
[FSCK] free segment_count matched with CP             [Ok..] [0xcb04]
[FSCK] next block offset is free                      [Ok..]
[FSCK] fixing SIT types
[FSCK] other corrupted bugs                           [Fail]

The root cause is:
If we open file w/ readonly flag, disk quota info won't be initialized
for this file, however, following mmap() will force to convert inline
inode via f2fs_convert_inline_inode(), which may increase block usage
for this inode w/o updating quota data, it causes inconsistent disk quota
info.

The issue will happen in following stack:
open(file, O_RDONLY)
mmap(file)
- f2fs_convert_inline_inode
 - f2fs_convert_inline_page
  - f2fs_reserve_block
   - f2fs_reserve_new_block
    - f2fs_reserve_new_blocks
     - f2fs_i_blocks_write
      - dquot_claim_block
inode->i_blocks increase, but the dqb_curspace keep the size for the dquots
is NULL.

To fix this issue, let's call dquot_initialize() anyway in both
f2fs_truncate() and f2fs_convert_inline_inode() functions to avoid potential
inconsistent quota data issue.

Fixes: 0abd675e ("f2fs: support plain user/group quota")
Signed-off-by: Daiyue Zhang <zhangdaiyue1@huawei.com>
Signed-off-by: Dehe Gu <gudehe@huawei.com>
Signed-off-by: Junchao Jiang <jiangjunchao1@huawei.com>
Signed-off-by: Ge Qiu <qiuge@huawei.com>
Signed-off-by: Yi Chen <chenyi77@huawei.com>
Reviewed-by: Chao Yu <yuchao0@huawei.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>