Re: 2.6.19-rc2-mm2 : empty files on vfat file system

[OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>]

Damien Wyart <damien.wyart@free.fr> writes:

>> > I have noticed something strange (and bad :) since using
>> > 2.6.19-rc2-mm2 (the problem is NOT present on 2.6.19-rc2-mm1 ; do
>> > not know for mainline, I have not been able to test yet, but I think
>> > there have not been recent changes in this area) : writing a file to
>> > a vfat fs (fat 32) writes it, but with size 0 and no content.
>
> * OGAWA Hirofumi <hirofumi@mail.parknet.co.jp> [2006-10-21 22:24]:
>> diff -puN fs/fat/inode.c~fs-prepare_write-fixes fs/fat/inode.c
>> --- a/fs/fat/inode.c~fs-prepare_write-fixes
>> +++ a/fs/fat/inode.c
>> @@ -150,7 +150,11 @@ static int fat_commit_write(struct file 
>>  			    unsigned from, unsigned to)
>>  {
>>  	struct inode *inode = page->mapping->host;
>> -	int err = generic_commit_write(file, page, from, to);
>> +	int err;
>> +	if (to - from > 0)
>> +		return 0;
>> +
>> +	err = generic_commit_write(file, page, from, to);
>>  	if (!err && !(MSDOS_I(inode)->i_attrs & ATTR_ARCH)) {
>>  		inode->i_mtime = inode->i_ctime = CURRENT_TIME_SEC;
>>  		MSDOS_I(inode)->i_attrs |= ATTR_ARCH;
>
>> This change does't update ->i_size. Could you just delete, and test
>> it? Anyway, this seems wrong even if it's "if ((to - from) == 0)".
>
> Reverting the change makes the problem go away. But I do not know if
> this is safe wrt the fs-prepare_write-fixes patch.

Yes, maybe another patch will be needed. However, I don't know the
background of this change. I'll make time and see what happened.
-- 
OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>