On 9/14/11 2:16 AM, Tao Ma wrote:
> From: Tao Ma <boyu.mt@xxxxxxxxxx>
>
> When we want to convert the unitialized extent in direct write,
> we can either do it in ext4_end_io_nolock(AIO case) or in
> ext4_ext_direct_IO(non AIO case) and EXT4_I(inode)->cur_aio_dio
> is a guard for ext4_ext_map_blocks to find the right case.
> In e9e3bcecf, we mistakenly change it by:
> - if (io)
> + if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) {
> io->flag = EXT4_IO_END_UNWRITTEN;
> - else
> + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
> + } else
> ext4_set_inode_state(inode,
> EXT4_STATE_DIO_UNWRITTEN);
>
> So now if we map 2 blocks, and the first one set the EXT_IO_END_UNWRITTEN, the
> 2nd mapping will set inode state because of the check for the flag. This is
> wrong.
Argh, yes, I think you are right. Pesky else clause. :(
Do you have a testcase for this? And what is the user-visible outcome of the error,
is it data corruption?
> Cc: Eric Sandeen <sandeen@xxxxxxxxxx>
> Cc: "Theodore Ts'o" <tytso@xxxxxxx>
> Signed-off-by: Tao Ma <boyu.mt@xxxxxxxxxx>
> ---
> fs/ext4/extents.c | 16 ++++++++++------
> 1 files changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext4/extents.c b/fs/ext4/extents.c
> index 57cf568..8db6743 100644
> --- a/fs/ext4/extents.c
> +++ b/fs/ext4/extents.c
> @@ -3190,9 +3190,11 @@ ext4_ext_handle_uninitialized_extents(handle_t *handle, struct inode *inode,
> * that this IO needs to conversion to written when IO is
> * completed
> */
> - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) {
> - io->flag = EXT4_IO_END_UNWRITTEN;
> - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
> + if (io) {
> + if (!(io->flag & EXT4_IO_END_UNWRITTEN)) {
> + io->flag = EXT4_IO_END_UNWRITTEN;
> + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
> + }
> } else
> ext4_set_inode_state(inode, EXT4_STATE_DIO_UNWRITTEN);
> if (ext4_should_dioread_nolock(inode))
> @@ -3572,9 +3574,11 @@ int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
> * that we need to perform conversion when IO is done.
> */
> if ((flags & EXT4_GET_BLOCKS_PRE_IO)) {
> - if (io && !(io->flag & EXT4_IO_END_UNWRITTEN)) {
> - io->flag = EXT4_IO_END_UNWRITTEN;
> - atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
> + if (io) {
> + if (!(io->flag & EXT4_IO_END_UNWRITTEN)) {
> + io->flag = EXT4_IO_END_UNWRITTEN;
> + atomic_inc(&EXT4_I(inode)->i_aiodio_unwritten);
> + }
> } else
> ext4_set_inode_state(inode,
> EXT4_STATE_DIO_UNWRITTEN);
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