Re: [PATCH 2/8] writeback: add wbc_to_write_flags()

From: Omar Sandoval
Date: Wed Aug 31 2016 - 19:33:09 EST


On Wed, Aug 31, 2016 at 11:05:45AM -0600, Jens Axboe wrote:
> Add wbc_to_write_flags(), which returns the write modifier flags to use,
> based on a struct writeback_control. No functional changes in this
> patch, but it prepares us for factoring other wbc fields for write type.
>
> Signed-off-by: Jens Axboe <axboe@xxxxxx>
> Reviewed-by: Jan Kara <jack@xxxxxxx>

[snip]

> diff --git a/include/linux/writeback.h b/include/linux/writeback.h
> index fc1e16c25a29..e1fc25172397 100644
> --- a/include/linux/writeback.h
> +++ b/include/linux/writeback.h
> @@ -100,6 +100,14 @@ struct writeback_control {
> #endif
> };
>
> +static inline int wbc_to_write_flags(struct writeback_control *wbc)
> +{
> + if (wbc->sync_mode == WB_SYNC_ALL)
> + return WRITE_SYNC;
> +
> + return WRITE;

I think this should be `return 0;` after the op/flags split. WRITE == 1,
so this would get interpreted as REQ_FAILFAST_DEV in bi_opf.

>From 2a222ca992c3 ("fs: have submit_bh users pass in op and flags
separately"):

@@ -1697,7 +1697,7 @@ static int __block_write_full_page(struct inode *inode, struct page *page,
struct buffer_head *bh, *head;
unsigned int blocksize, bbits;
int nr_underway = 0;
- int write_op = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : WRITE);
+ int write_flags = (wbc->sync_mode == WB_SYNC_ALL ? WRITE_SYNC : 0);

--
Omar