> Attaching the updated patch.
>
> Mingming,
>
> Can you update the patchqueu with the below attached patch ?
>
> -aneesh
>
> mm: Add range_cont mode for writeback.
>
> From: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> Filesystems like ext4 needs to start a new transaction in
> the writepages for block allocation. This happens with delayed
> allocation and there is limit to how many credits we can request
> from the journal layer. So we call write_cache_pages multiple
> times with wbc->nr_to_write set to the maximum possible value
> limitted by the max journal credits available.
>
> Add a new mode to writeback that enables us to handle this
> behaviour. In the new mode we update the wbc->range_start
> to point to the new offset to be written. Next call to
> call to write_cache_pages will start writeout from specified
> range_start offset. In the new mode we also limit writing
> to the specified wbc->range_end.
>
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Acked-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
>
> include/linux/writeback.h | 1 +
> mm/page-writeback.c | 3 +++
> 2 files changed, 4 insertions(+), 0 deletions(-)
>
>
> diff --git a/include/linux/writeback.h b/include/linux/writeback.h
> index f462439..0d8573e 100644
> --- a/include/linux/writeback.h
> +++ b/include/linux/writeback.h
> @@ -63,6 +63,7 @@ struct writeback_control {
> unsigned for_writepages:1; /* This is a writepages() call */
> unsigned range_cyclic:1; /* range_start is cyclic */
> unsigned more_io:1; /* more io to be dispatched */
> + unsigned range_cont:1;
> };
>
> /*
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 789b6ad..ded57d5 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -956,6 +956,9 @@ int write_cache_pages(struct address_space *mapping,
> }
> if (wbc->range_cyclic || (range_whole && wbc->nr_to_write > 0))
> mapping->writeback_index = index;
> +
> + if (wbc->range_cont)
> + wbc->range_start = index << PAGE_CACHE_SHIFT;
> return ret;
> }
> EXPORT_SYMBOL(write_cache_pages);
--
Jan Kara <jack@xxxxxxx>
SUSE Labs, CR
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