Re: [PATCH v2] fat: preallocate space before expanding in fat_cont_expand()

[OGAWA Hirofumi]

OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx> writes:

>>  static int fat_cont_expand(struct inode *inode, loff_t size)
>>  {
>>  	struct address_space *mapping = inode->i_mapping;
>>  	loff_t start = inode->i_size, count = size - inode->i_size;
>>  	int err;
>>  
>> -	err = generic_cont_expand_simple(inode, size);
>> +	/*
>> +	 * Preallocating space here is more efficient than during
>> +	 * generic_cont_expand_simple() because of batching.
>> +	 */
>> +	err = inode_newsize_ok(inode, size);
>>  	if (err)
>>  		goto out;
>> +	err = fat_preallocate(inode, size);
>> +	if (err)
>> +		goto out;
>> +	err = generic_cont_expand_simple(inode, size);
>> +	if (err) {
>> +		down_write(&MSDOS_I(inode)->truncate_lock);
>> +		fat_truncate_blocks(inode, inode->i_size);
>> +		up_write(&MSDOS_I(inode)->truncate_lock);
>
> Is this fat_truncate_blocks() really required?
>
>> +		goto out;
>> +	}

And maybe this will change the user visible behavior for ENOSPC. (I'm
not sure if it is ok for now)

Thanks.
-- 
OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>