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SubjectRe: [PATCH 3/3] fs: fat: add ioctl method in fat filesystem driver
Date
chenchacha <chen.chenchacha@foxmail.com> writes:

> On 01/29/2018 09:02 PM, OGAWA Hirofumi wrote:
>> ChenGuanqiao <chen.chenchacha@foxmail.com> writes:
>>
>>> +static int fat_check_d_characters(char *label, unsigned long len)
>>> +{
>>> + int i;
>>> +
>>> + for (i = 0; i < len; ++i) {
>>> + switch (label[i]) {
>>> + case 'a' ... 'z':
>>> + label[i] = __toupper(label[i]);
>>> + case 'A' ... 'Z':
>>> + case '0' ... '9':
>>> + case '_':
>>> + case 0x20:
>>> + continue;
>>> + default:
>>> + return -EINVAL;
>>> + }
>> Same question with previous though, what windows do if label = "a b c"?
>> (this is including space other than end of name or extension.)
> In win7, the volume label will be capitalized, and leaving spaces.
> Or, you mean I need to fill the rest of the space with "0x20"?

I see. However, what win7 stored, BTW? It was "A B C ", or anything
other?

>>> +static int fat_ioctl_set_volume_label(struct file *file,
>>> + u8 __user *vol_label)
>>> +{
>>> + int err = 0;
>>> + u8 label[MSDOS_NAME];
>>> + struct timespec ts;
>>> + struct buffer_head *boot_bh;
>>> + struct buffer_head *vol_bh;
>>> + struct msdos_dir_entry *de;
>>> + struct fat_boot_sector *b;
>>> + struct inode *inode = file_inode(file);
>>> + struct super_block *sb = inode->i_sb;
>>> + struct msdos_sb_info *sbi = MSDOS_SB(sb);
>>> +
>> [...]
> I need remove "struct msdos_sb_info *sbi"?

If you didn't use sbi anymore, you should remove.

>>> + err = mnt_want_write_file(file);
>>> + if (err)
>>> + goto out;
>>> +
>>> + down_write(&sb->s_umount);
>> Looks like inode_lock() for rootdir is gone. It is necessary to
>> traverse+modify.
> Is it wrong for me to use the inode_lock() in patch v7? I need to lock
> inode here, and turn off immediately after

inode_lock() is necessary to protect race with other dir operations.

I asked at v7, locking order to prevent the AB locking order bug.

I.e.
mnt_want_write_file => down_write => inode_lock()
vs
down_write => mnt_want_write_file => inode_lock()

Which is right one?

> mark_buffer_dirty(vol_bh)?

What is this asking?
--
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>

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