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

[Damien Wyart <damien.wyart@free.fr>]

> > 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.

-- 
Damien Wyart