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Date: Wed, 16 Sep 2009 15:32:20 +0200
From: Jan Kara <jack@...e.cz>
To: Jens Axboe <jens.axboe@...cle.com>
Cc: linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
chris.mason@...cle.com, hch@...radead.org, tytso@....edu,
akpm@...ux-foundation.org, jack@...e.cz, trond.myklebust@....uio.no
Subject: Re: [PATCH 04/16] writeback: make wb_writeback() take an argument
structure
On Wed 16-09-09 15:24:42, Jens Axboe wrote:
> We need to be able to pass in range_cyclic as well, so instead
> of growing yet another argument, split the arguments into a
> struct wb_writeback_args structure that we can use internally.
> Also makes it easier to just copy all members to an on-stack
> struct, since we can't access work after clearing the pending
> bit.
Looks good.
Acked-by: Jan Kara <jack@...e.cz>
Honza
>
> Signed-off-by: Jens Axboe <jens.axboe@...cle.com>
> ---
> fs/fs-writeback.c | 78 +++++++++++++++++++++++++++++++++-------------------
> 1 files changed, 49 insertions(+), 29 deletions(-)
>
> diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c
> index 783ed44..c5e9122 100644
> --- a/fs/fs-writeback.c
> +++ b/fs/fs-writeback.c
> @@ -35,6 +35,17 @@
> int nr_pdflush_threads;
>
> /*
> + * Passed into wb_writeback(), essentially a subset of writeback_control
> + */
> +struct wb_writeback_args {
> + long nr_pages;
> + struct super_block *sb;
> + enum writeback_sync_modes sync_mode;
> + int for_kupdate;
> + int range_cyclic;
> +};
> +
> +/*
> * Work items for the bdi_writeback threads
> */
> struct bdi_work {
> @@ -45,9 +56,7 @@ struct bdi_work {
> unsigned long seen;
> atomic_t pending;
>
> - struct super_block *sb;
> - unsigned long nr_pages;
> - enum writeback_sync_modes sync_mode;
> + struct wb_writeback_args args;
>
> unsigned long state;
> };
> @@ -69,9 +78,11 @@ static inline void bdi_work_init(struct bdi_work *work,
> struct writeback_control *wbc)
> {
> INIT_RCU_HEAD(&work->rcu_head);
> - work->sb = wbc->sb;
> - work->nr_pages = wbc->nr_to_write;
> - work->sync_mode = wbc->sync_mode;
> + work->args.sb = wbc->sb;
> + work->args.nr_pages = wbc->nr_to_write;
> + work->args.sync_mode = wbc->sync_mode;
> + work->args.range_cyclic = wbc->range_cyclic;
> + work->args.for_kupdate = 0;
> work->state = WS_USED;
> }
>
> @@ -106,7 +117,7 @@ static void bdi_work_free(struct rcu_head *head)
>
> static void wb_work_complete(struct bdi_work *work)
> {
> - const enum writeback_sync_modes sync_mode = work->sync_mode;
> + const enum writeback_sync_modes sync_mode = work->args.sync_mode;
>
> /*
> * For allocated work, we can clear the done/seen bit right here.
> @@ -653,17 +664,16 @@ static inline bool over_bground_thresh(void)
> * older_than_this takes precedence over nr_to_write. So we'll only write back
> * all dirty pages if they are all attached to "old" mappings.
> */
> -static long wb_writeback(struct bdi_writeback *wb, long nr_pages,
> - struct super_block *sb,
> - enum writeback_sync_modes sync_mode, int for_kupdate)
> +static long wb_writeback(struct bdi_writeback *wb,
> + struct wb_writeback_args *args)
> {
> struct writeback_control wbc = {
> .bdi = wb->bdi,
> - .sb = sb,
> - .sync_mode = sync_mode,
> + .sb = args->sb,
> + .sync_mode = args->sync_mode,
> .older_than_this = NULL,
> - .for_kupdate = for_kupdate,
> - .range_cyclic = 1,
> + .for_kupdate = args->for_kupdate,
> + .range_cyclic = args->range_cyclic,
> };
> unsigned long oldest_jif;
> long wrote = 0;
> @@ -673,13 +683,18 @@ static long wb_writeback(struct bdi_writeback *wb, long nr_pages,
> oldest_jif = jiffies -
> msecs_to_jiffies(dirty_expire_interval * 10);
> }
> + if (!wbc.range_cyclic) {
> + wbc.range_start = 0;
> + wbc.range_end = LLONG_MAX;
> + }
>
> for (;;) {
> /*
> * Don't flush anything for non-integrity writeback where
> * no nr_pages was given
> */
> - if (!for_kupdate && nr_pages <= 0 && sync_mode == WB_SYNC_NONE)
> + if (!args->for_kupdate && args->nr_pages <= 0 &&
> + args->sync_mode == WB_SYNC_NONE)
> break;
>
> /*
> @@ -687,7 +702,8 @@ static long wb_writeback(struct bdi_writeback *wb, long nr_pages,
> * periodic background writeout and we are below the
> * background dirty threshold, don't do anything
> */
> - if (for_kupdate && nr_pages <= 0 && !over_bground_thresh())
> + if (args->for_kupdate && args->nr_pages <= 0 &&
> + !over_bground_thresh())
> break;
>
> wbc.more_io = 0;
> @@ -695,7 +711,7 @@ static long wb_writeback(struct bdi_writeback *wb, long nr_pages,
> wbc.nr_to_write = MAX_WRITEBACK_PAGES;
> wbc.pages_skipped = 0;
> writeback_inodes_wb(wb, &wbc);
> - nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
> + args->nr_pages -= MAX_WRITEBACK_PAGES - wbc.nr_to_write;
> wrote += MAX_WRITEBACK_PAGES - wbc.nr_to_write;
>
> /*
> @@ -749,8 +765,16 @@ static long wb_check_old_data_flush(struct bdi_writeback *wb)
> global_page_state(NR_UNSTABLE_NFS) +
> (inodes_stat.nr_inodes - inodes_stat.nr_unused);
>
> - if (nr_pages)
> - return wb_writeback(wb, nr_pages, NULL, WB_SYNC_NONE, 1);
> + if (nr_pages) {
> + struct wb_writeback_args args = {
> + .nr_pages = nr_pages,
> + .sync_mode = WB_SYNC_NONE,
> + .for_kupdate = 1,
> + .range_cyclic = 1,
> + };
> +
> + return wb_writeback(wb, &args);
> + }
>
> return 0;
> }
> @@ -762,35 +786,31 @@ long wb_do_writeback(struct bdi_writeback *wb, int force_wait)
> {
> struct backing_dev_info *bdi = wb->bdi;
> struct bdi_work *work;
> - long nr_pages, wrote = 0;
> + long wrote = 0;
>
> while ((work = get_next_work_item(bdi, wb)) != NULL) {
> - enum writeback_sync_modes sync_mode;
> -
> - nr_pages = work->nr_pages;
> + struct wb_writeback_args args = work->args;
>
> /*
> * Override sync mode, in case we must wait for completion
> */
> if (force_wait)
> - work->sync_mode = sync_mode = WB_SYNC_ALL;
> - else
> - sync_mode = work->sync_mode;
> + work->args.sync_mode = args.sync_mode = WB_SYNC_ALL;
>
> /*
> * If this isn't a data integrity operation, just notify
> * that we have seen this work and we are now starting it.
> */
> - if (sync_mode == WB_SYNC_NONE)
> + if (args.sync_mode == WB_SYNC_NONE)
> wb_clear_pending(wb, work);
>
> - wrote += wb_writeback(wb, nr_pages, work->sb, sync_mode, 0);
> + wrote += wb_writeback(wb, &args);
>
> /*
> * This is a data integrity writeback, so only do the
> * notification when we have completed the work.
> */
> - if (sync_mode == WB_SYNC_ALL)
> + if (args.sync_mode == WB_SYNC_ALL)
> wb_clear_pending(wb, work);
> }
>
> --
> 1.6.4.1.207.g68ea
>
--
Jan Kara <jack@...e.cz>
SUSE Labs, CR
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