On Wed, Mar 22, 2017 at 05:44:22PM +0100, heinzm@xxxxxxxxxx wrote:
> From: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
>
> Upstream commit 2ded370373a400c20cf0c6e941e724e61582a867
> started the addition of "write-back" mode to MD (raid5-cache),
> i.e. support write-back caching on the raid journal device.
>
> In order to allow the dm-raid target to switch between
> the available "write-through" and "write-back" modes,
> provide new r5c_journal_mode_set() API.
>
> Use the new API in existing r5c_journal_mode_store()
Looks good to me, if this will be routed through dm tree, you can add:
Acked-by: Shaohua Li <shli@xxxxxx>
> Signed-off-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
> ---
> drivers/md/raid5-cache.c | 62 ++++++++++++++++++++++++++----------------------
> drivers/md/raid5.h | 11 +++++++++
> 2 files changed, 45 insertions(+), 28 deletions(-)
>
> diff --git a/drivers/md/raid5-cache.c b/drivers/md/raid5-cache.c
> index 3f307be..218b6f3 100644
> --- a/drivers/md/raid5-cache.c
> +++ b/drivers/md/raid5-cache.c
> @@ -53,16 +53,6 @@
> */
> #define R5L_POOL_SIZE 4
>
> -/*
> - * r5c journal modes of the array: write-back or write-through.
> - * write-through mode has identical behavior as existing log only
> - * implementation.
> - */
> -enum r5c_journal_mode {
> - R5C_JOURNAL_MODE_WRITE_THROUGH = 0,
> - R5C_JOURNAL_MODE_WRITE_BACK = 1,
> -};
> -
> static char *r5c_journal_mode_str[] = {"write-through",
> "write-back"};
> /*
> @@ -2327,40 +2317,56 @@ static ssize_t r5c_journal_mode_show(struct mddev *mddev, char *page)
> return ret;
> }
>
> -static ssize_t r5c_journal_mode_store(struct mddev *mddev,
> - const char *page, size_t length)
> +/*
> + * Set journal cache mode on @mddev (external API initially needed by dm-raid).
> + *
> + * @mode as defined in 'enum r5c_journal_mode'.
> + *
> + */
> +int r5c_journal_mode_set(struct mddev *mddev, int mode)
> {
> struct r5conf *conf = mddev->private;
> struct r5l_log *log = conf->log;
> - int val = -1, i;
> - int len = length;
>
> if (!log)
> return -ENODEV;
>
> - if (len && page[len - 1] == '\n')
> - len -= 1;
> - for (i = 0; i < ARRAY_SIZE(r5c_journal_mode_str); i++)
> - if (strlen(r5c_journal_mode_str[i]) == len &&
> - strncmp(page, r5c_journal_mode_str[i], len) == 0) {
> - val = i;
> - break;
> - }
> - if (val < R5C_JOURNAL_MODE_WRITE_THROUGH ||
> - val > R5C_JOURNAL_MODE_WRITE_BACK)
> + if (mode < R5C_JOURNAL_MODE_WRITE_THROUGH ||
> + mode > R5C_JOURNAL_MODE_WRITE_BACK)
> return -EINVAL;
>
> if (raid5_calc_degraded(conf) > 0 &&
> - val == R5C_JOURNAL_MODE_WRITE_BACK)
> + mode == R5C_JOURNAL_MODE_WRITE_BACK)
> return -EINVAL;
>
> mddev_suspend(mddev);
> - conf->log->r5c_journal_mode = val;
> + conf->log->r5c_journal_mode = mode;
> mddev_resume(mddev);
>
> pr_debug("md/raid:%s: setting r5c cache mode to %d: %s\n",
> - mdname(mddev), val, r5c_journal_mode_str[val]);
> - return length;
> + mdname(mddev), mode, r5c_journal_mode_str[mode]);
> + return 0;
> +}
> +EXPORT_SYMBOL(r5c_journal_mode_set);
> +
> +static ssize_t r5c_journal_mode_store(struct mddev *mddev,
> + const char *page, size_t length)
> +{
> + int mode = ARRAY_SIZE(r5c_journal_mode_str);
> + size_t len = length;
> +
> + if (len < 2)
> + return -EINVAL;
> +
> + if (page[len - 1] == '\n')
> + len--;
> +
> + while (mode--)
> + if (strlen(r5c_journal_mode_str[mode]) == len &&
> + !strncmp(page, r5c_journal_mode_str[mode], len))
> + break;
> +
> + return r5c_journal_mode_set(mddev, mode) ?: length;
> }
>
> struct md_sysfs_entry
> diff --git a/drivers/md/raid5.h b/drivers/md/raid5.h
> index 4bb27b9..ec8ca15 100644
> --- a/drivers/md/raid5.h
> +++ b/drivers/md/raid5.h
> @@ -547,6 +547,16 @@ struct r5worker_group {
> int stripes_cnt;
> };
>
> +/*
> + * r5c journal modes of the array: write-back or write-through.
> + * write-through mode has identical behavior as existing log only
> + * implementation.
> + */
> +enum r5c_journal_mode {
> + R5C_JOURNAL_MODE_WRITE_THROUGH = 0,
> + R5C_JOURNAL_MODE_WRITE_BACK = 1,
> +};
> +
> enum r5_cache_state {
> R5_INACTIVE_BLOCKED, /* release of inactive stripes blocked,
> * waiting for 25% to be free
> @@ -795,4 +805,5 @@ extern void r5c_check_cached_full_stripe(struct r5conf *conf);
> extern struct md_sysfs_entry r5c_journal_mode;
> extern void r5c_update_on_rdev_error(struct mddev *mddev);
> extern bool r5c_big_stripe_cached(struct r5conf *conf, sector_t sect);
> +extern int r5c_journal_mode_set(struct mddev *mddev, int journal_mode);
> #endif
> --
> 2.9.3
>
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