On Thu, Jan 12, 2017 at 05:22:41PM -0800, Song Liu wrote:
> With write back cache, we use orig_page to do prexor. This patch
> makes sure we read data into orig_page for it.
>
> Flag R5_OrigPageUPTDODATE is added to show whether orig_page
> has the latest data from raid disk.
>
> We introduce a helper function uptodate_for_rmw() to simplify
> the a couple conditions in handle_stripe_dirtying().
applied patch 2 & 3
Thanks,
Shaohua
>
> Signed-off-by: Song Liu <songliubraving@xxxxxx>
> ---
> drivers/md/raid5-cache.c | 2 ++
> drivers/md/raid5.c | 44 +++++++++++++++++++++++++++++++++++---------
> drivers/md/raid5.h | 5 +++++
> 3 files changed, 42 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> index 2bbc38b..248fede 100644
> --- a/drivers/md/raid5-cache.c
> +++ b/drivers/md/raid5-cache.c
> @@ -2459,6 +2459,8 @@ void r5c_release_extra_page(struct stripe_head *sh)
> struct page *p = sh->dev[i].orig_page;
>
> sh->dev[i].orig_page = sh->dev[i].page;
> + clear_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
> +
> if (!using_disk_info_extra_page)
> put_page(p);
> }
> diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
> index 0d2082d..3e75289 100644
> --- a/drivers/md/raid5.c
> +++ b/drivers/md/raid5.c
> @@ -1056,7 +1056,17 @@ static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
>
> if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
> WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
> - sh->dev[i].vec.bv_page = sh->dev[i].page;
> +
> + if (!op_is_write(op) &&
> + test_bit(R5_InJournal, &sh->dev[i].flags))
> + /*
> + * issuing read for a page in journal, this
> + * must be preparing for prexor in rmw; read
> + * the data into orig_page
> + */
> + sh->dev[i].vec.bv_page = sh->dev[i].orig_page;
> + else
> + sh->dev[i].vec.bv_page = sh->dev[i].page;
> bi->bi_vcnt = 1;
> bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
> bi->bi_io_vec[0].bv_offset = 0;
> @@ -2421,6 +2431,13 @@ static void raid5_end_read_request(struct bio * bi)
> } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
> clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
>
> + if (test_bit(R5_InJournal, &sh->dev[i].flags))
> + /*
> + * end read for a page in journal, this
> + * must be preparing for prexor in rmw
> + */
> + set_bit(R5_OrigPageUPTDODATE, &sh->dev[i].flags);
> +
> if (atomic_read(&rdev->read_errors))
> atomic_set(&rdev->read_errors, 0);
> } else {
> @@ -3635,6 +3652,21 @@ static void handle_stripe_clean_event(struct r5conf *conf,
> break_stripe_batch_list(head_sh, STRIPE_EXPAND_SYNC_FLAGS);
> }
>
> +/*
> + * For RMW in write back cache, we need extra page in prexor to store the
> + * old data. This page is stored in dev->orig_page.
> + *
> + * This function checks whether we have data for prexor. The exact logic
> + * is:
> + * R5_UPTODATE && (!R5_InJournal || R5_OrigPageUPTDODATE)
> + */
> +static inline bool uptodate_for_rmw(struct r5dev *dev)
> +{
> + return (test_bit(R5_UPTODATE, &dev->flags)) &&
> + (!test_bit(R5_InJournal, &dev->flags) ||
> + test_bit(R5_OrigPageUPTDODATE, &dev->flags));
> +}
> +
> static int handle_stripe_dirtying(struct r5conf *conf,
> struct stripe_head *sh,
> struct stripe_head_state *s,
> @@ -3666,9 +3698,7 @@ static int handle_stripe_dirtying(struct r5conf *conf,
> if ((dev->towrite || i == sh->pd_idx || i == sh->qd_idx ||
> test_bit(R5_InJournal, &dev->flags)) &&
> !test_bit(R5_LOCKED, &dev->flags) &&
> - !((test_bit(R5_UPTODATE, &dev->flags) &&
> - (!test_bit(R5_InJournal, &dev->flags) ||
> - dev->page != dev->orig_page)) ||
> + !(uptodate_for_rmw(dev) ||
> test_bit(R5_Wantcompute, &dev->flags))) {
> if (test_bit(R5_Insync, &dev->flags))
> rmw++;
> @@ -3680,7 +3710,6 @@ static int handle_stripe_dirtying(struct r5conf *conf,
> i != sh->pd_idx && i != sh->qd_idx &&
> !test_bit(R5_LOCKED, &dev->flags) &&
> !(test_bit(R5_UPTODATE, &dev->flags) ||
> - test_bit(R5_InJournal, &dev->flags) ||
> test_bit(R5_Wantcompute, &dev->flags))) {
> if (test_bit(R5_Insync, &dev->flags))
> rcw++;
> @@ -3734,9 +3763,7 @@ static int handle_stripe_dirtying(struct r5conf *conf,
> i == sh->pd_idx || i == sh->qd_idx ||
> test_bit(R5_InJournal, &dev->flags)) &&
> !test_bit(R5_LOCKED, &dev->flags) &&
> - !((test_bit(R5_UPTODATE, &dev->flags) &&
> - (!test_bit(R5_InJournal, &dev->flags) ||
> - dev->page != dev->orig_page)) ||
> + !(uptodate_for_rmw(dev) ||
> test_bit(R5_Wantcompute, &dev->flags)) &&
> test_bit(R5_Insync, &dev->flags)) {
> if (test_bit(STRIPE_PREREAD_ACTIVE,
> @@ -3763,7 +3790,6 @@ static int handle_stripe_dirtying(struct r5conf *conf,
> i != sh->pd_idx && i != sh->qd_idx &&
> !test_bit(R5_LOCKED, &dev->flags) &&
> !(test_bit(R5_UPTODATE, &dev->flags) ||
> - test_bit(R5_InJournal, &dev->flags) ||
> test_bit(R5_Wantcompute, &dev->flags))) {
> rcw++;
> if (test_bit(R5_Insync, &dev->flags) &&
> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> index c582086..50855ad 100644
> --- a/drivers/md/raid5.h
> +++ b/drivers/md/raid5.h
> @@ -322,6 +322,11 @@ enum r5dev_flags {
> * data and parity being written are in the journal
> * device
> */
> + R5_OrigPageUPTDODATE, /* with write back cache, we read old data into
> + * dev->orig_page for prexor. When this flag is
> + * set, orig_page contains latest data in the
> + * raid disk.
> + */
> };
>
> /*
> --
> 2.9.3
>
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