On Mon, Apr 08, 2013 at 11:32:28PM +0200, Jan Kara wrote:
> Make sure extent conversion after DIO happens while i_dio_count is still
> elevated so that inode_dio_wait() waits until extent conversion is done.
> This removes the need for explicit waiting for extent conversion in some
> cases.
>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
Reviewed-by: Zheng Liu <wenqing.lz@xxxxxxxxxx>
Regards,
- Zheng
> ---
> fs/ext4/inode.c | 12 ++++++++++--
> 1 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index f8e78ce..f493ec2 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2914,11 +2914,18 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
>
> BUG_ON(iocb->private == NULL);
>
> + /*
> + * Make all waiters for direct IO properly wait also for extent
> + * conversion. This also disallows race between truncate() and
> + * overwrite DIO as i_dio_count needs to be incremented under i_mutex.
> + */
> + if (rw == WRITE)
> + atomic_inc(&inode->i_dio_count);
> +
> /* If we do a overwrite dio, i_mutex locking can be released */
> overwrite = *((int *)iocb->private);
>
> if (overwrite) {
> - atomic_inc(&inode->i_dio_count);
> down_read(&EXT4_I(inode)->i_data_sem);
> mutex_unlock(&inode->i_mutex);
> }
> @@ -3013,9 +3020,10 @@ static ssize_t ext4_ext_direct_IO(int rw, struct kiocb *iocb,
> }
>
> retake_lock:
> + if (rw == WRITE)
> + inode_dio_done(inode);
> /* take i_mutex locking again if we do a ovewrite dio */
> if (overwrite) {
> - inode_dio_done(inode);
> up_read(&EXT4_I(inode)->i_data_sem);
> mutex_lock(&inode->i_mutex);
> }
> --
> 1.7.1
>
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