On Tue, Oct 20, 2009 at 09:24:38AM +0200, Jan Kara wrote:
> We cannot rely on buffer dirty bits during fsync because pdflush can come
> before fsync is called and clear dirty bits without forcing a transaction
> commit. What we do is that we track which transaction has last changed
> the inode and which transaction last changed allocation and force it to
> disk on fsync.
>
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/ext4/ext4.h | 7 +++++++
> fs/ext4/extents.c | 5 +++++
> fs/ext4/fsync.c | 40 +++++++++++++++++-----------------------
> fs/ext4/inode.c | 34 ++++++++++++++++++++++++++++++++++
> 4 files changed, 63 insertions(+), 23 deletions(-)
>
> diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
> index 984ca0c..5639f30 100644
> --- a/fs/ext4/ext4.h
> +++ b/fs/ext4/ext4.h
> @@ -702,6 +702,13 @@ struct ext4_inode_info {
> struct list_head i_aio_dio_complete_list;
> /* current io_end structure for async DIO write*/
> ext4_io_end_t *cur_aio_dio;
> +
> + /*
> + * Transactions that contain inode's metadata needed to complete
> + * fsync and fdatasync, respectively.
> + */
> + atomic_t i_sync_tid;
> + atomic_t i_datasync_tid;
> };
>
> /*
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 10539e3..3e167f6 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -3315,6 +3315,11 @@ int ext4_ext_get_blocks(handle_t *handle, struct inode *inode,
> newblock = ext_pblock(&newex);
> allocated = ext4_ext_get_actual_len(&newex);
> set_buffer_new(bh_result);
> +
> + atomic_set(&EXT4_I(inode)->i_sync_tid, handle->h_transaction->t_tid);
> + atomic_set(&EXT4_I(inode)->i_datasync_tid,
> + handle->h_transaction->t_tid);
> + printk("Datasync tid %u\n", handle->h_transaction->t_tid);
The printk need to be removed ?
Also i am wondering wether we need to update i_datasync_tid only if we
allocate new blocks ? How about writing to an fallocate area. I guess
we need to track the transaction in which we are marking an extent
initialized.
-aneesh
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