Re: [PATCH 1/2] fs: truncate blocks outside i_size after generic_file_direct_write error

[Jeff Moyer <jmoyer@redhat.com>]

Dmitri Monakhov <dmonakhov@openvz.org> writes:

> We need to remove block that was allocated in generic_file_direct_write()
> if we fail. We have to do it *regardless* to blocksize. At least ext2,
> ext3 and reiserfs interpret (i_size < biggest block) condition as error.
> Fsck will complain about wrong i_size. Then fsck will fix the error
> by changing i_size according to the biggest block. This is bad because
> this blocks contain gurbage from previous write attempt. And result in
> data corruption.
>
> In order to call vmtruncate() we have to hold host->i_mutex. This is true
> for generic_file_aio_write(). In fact occasionally it is also true for all
> generic_file_aio_write_nolock() callers except blockdev. But this situation
> may change someday. This patch fix only generic_write_aio_write() case.
> BTW: update generic_file_direct_write's comment with currently outdated.

Do you have a test case for this, by any chance?

Cheers,

Jeff