[PATCH v3 36/39] ubifs: implement ubifs_get_qsize to get quota size in ubifs

[Dongsheng Yang]

On 09/16/2015 06:00 PM, Jan Kara wrote:
> On Tue 15-09-15 17:02:31, Dongsheng Yang wrote:
>> We only care the size of regular file in ubifs for quota.
>> The reason is similar with the comment in ubifs_getattr().
>>
>> Signed-off-by: Dongsheng Yang <yangds.fnst at cn.fujitsu.com>
>> ---
>>   fs/ubifs/dir.c   |  3 +++
>>   fs/ubifs/file.c  | 22 ++++++++++++++++++++++
>>   fs/ubifs/ubifs.h |  1 +
>>   3 files changed, 26 insertions(+)
>>
>> diff --git a/fs/ubifs/dir.c b/fs/ubifs/dir.c
>> index 802c6ad..0d3d6d3 100644
>> --- a/fs/ubifs/dir.c
>> +++ b/fs/ubifs/dir.c
>> @@ -1205,6 +1205,9 @@ const struct inode_operations ubifs_dir_inode_operations = {
>>   #ifdef CONFIG_UBIFS_ATIME_SUPPORT
>>   	.update_time = ubifs_update_time,
>>   #endif
>> +#ifdef CONFIG_QUOTA
>> +	.get_qsize	= ubifs_get_qsize,
>> +#endif
>>   };
>>
>>   const struct file_operations ubifs_dir_operations = {
>> diff --git a/fs/ubifs/file.c b/fs/ubifs/file.c
>> index b57ccf3..f1d792a 100644
>> --- a/fs/ubifs/file.c
>> +++ b/fs/ubifs/file.c
>> @@ -1636,6 +1636,22 @@ static int ubifs_file_mmap(struct file *file, struct vm_area_struct *vma)
>>   	return 0;
>>   }
>>
>> +/*
>> + * ubifs_get_qsize: get the quota size of a file
>> + * @inode: inode which we are going to get the qsize
>> + *
>> + * We only care the size of regular file in ubifs
>> + * for quota. The reason is similar with the comment
>> + * in ubifs_getattr().
>> + */
>> +ssize_t ubifs_get_qsize(struct inode *inode)
>> +{
>> +	if (S_ISREG(inode->i_mode))
>> +		return i_size_read(inode);
>> +	else
>> +		return 0;
>> +}
>> +
>
> The quota space is accounted in bytes. So why don't you store appropriate
> number of bytes the file consumes in i_blocks / i_bytes? Reiserfs can also
> have files occupying only say 100 bytes and everything works properly
> there so I don't see why ubifs needs to differ.

Ha, yes, we did not keep i_blocks in ubifs currently. Because we have
no blocks in ubifs. Although we can simulate a i_block for quota, I
did not do it. Let me try to show what I am thinking here.

(1).Block file system are counting space with blocks. Then the quota
could works in (dquot_alloc_block & i_blocks) way. I mean, account
spaces by dquot_alloc_block() and FIOQSIZE can get the qsize from
i_blocks.

(2). But ubifs has no blocks, then I choose another way to do it,
(quot_alloc_space & i_size). That means, we account quota spaces
in ubifs by dquot_alloc_space() and want FIOSIZE to get i_size
of inodes. Then there is no notion of *block* but only space.

So, I want to make FIOSIZE more flexible here to introduce a get_qsize()
into inode_operations.

Yang
>
> 								Honza
>
>>   const struct address_space_operations ubifs_file_address_operations = {
>>   	.readpage       = ubifs_readpage,
>>   	.writepage      = ubifs_writepage,
>> @@ -1656,6 +1672,9 @@ const struct inode_operations ubifs_file_inode_operations = {
>>   #ifdef CONFIG_UBIFS_ATIME_SUPPORT
>>   	.update_time = ubifs_update_time,
>>   #endif
>> +#ifdef CONFIG_QUOTA
>> +	.get_qsize	= ubifs_get_qsize,
>> +#endif
>>   };
>>
>>   const struct inode_operations ubifs_symlink_inode_operations = {
>> @@ -1670,6 +1689,9 @@ const struct inode_operations ubifs_symlink_inode_operations = {
>>   #ifdef CONFIG_UBIFS_ATIME_SUPPORT
>>   	.update_time = ubifs_update_time,
>>   #endif
>> +#ifdef CONFIG_QUOTA
>> +	.get_qsize	= ubifs_get_qsize,
>> +#endif
>>   };
>>
>>   const struct file_operations ubifs_file_operations = {
>> diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
>> index 99cf10c..21b5dc0 100644
>> --- a/fs/ubifs/ubifs.h
>> +++ b/fs/ubifs/ubifs.h
>> @@ -1759,6 +1759,7 @@ int ubifs_read_block(struct inode *inode, void *addr, unsigned int block,
>>   int ubifs_fsync(struct file *file, loff_t start, loff_t end, int datasync);
>>   int ubifs_setattr(struct dentry *dentry, struct iattr *attr);
>>   int ubifs_update_time(struct inode *inode, struct timespec *time, int flags);
>> +ssize_t ubifs_get_qsize(struct inode *inode);
>>
>>   /* dir.c */
>>   struct inode *ubifs_new_inode(struct ubifs_info *c, const struct inode *dir,
>> --
>> 1.8.4.2
>>