On Mon, Jan 06, 2025 at 10:54:38AM +0100, Christoph Hellwig wrote:
> __xfs_buf_submit calls xfs_buf_ioend when b_io_remaining hits zero. For
> in-memory buftargs b_io_remaining is never incremented from it's initial
> value of 1, so this always happens. Thus the extra call to xfs_buf_ioend
> in _xfs_buf_ioapply causes a double completion. Fortunately
> __xfs_buf_submit is only used for synchronous reads on in-memory buftargs
> due to the peculiarities of how they work, so this is mostly harmless and
> just causes a little extra work to be done.
Tempted to add:
Cc: <stable@xxxxxxxxxxxxxxx> # v6.9
though I think backporting isn't strictly necessary because in-memory
buffers don't have log items, right? If so, then we don't need to cc
stable.
Reviewed-by: "Darrick J. Wong" <djwong@xxxxxxxxxx>
--D
> Fixes: 5076a6040ca1 ("xfs: support in-memory buffer cache targets")
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> fs/xfs/xfs_buf.c | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/fs/xfs/xfs_buf.c b/fs/xfs/xfs_buf.c
> index aa63b8efd782..787caf0c3254 100644
> --- a/fs/xfs/xfs_buf.c
> +++ b/fs/xfs/xfs_buf.c
> @@ -1656,10 +1656,8 @@ _xfs_buf_ioapply(
> op |= REQ_META;
>
> /* in-memory targets are directly mapped, no IO required. */
> - if (xfs_buftarg_is_mem(bp->b_target)) {
> - xfs_buf_ioend(bp);
> + if (xfs_buftarg_is_mem(bp->b_target))
> return;
> - }
>
> /*
> * Walk all the vectors issuing IO on them. Set up the initial offset
> --
> 2.45.2
>
>
