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Commit 78e470c2 authored by Heinz Mauelshagen's avatar Heinz Mauelshagen Committed by Mike Snitzer
Browse files

md: add raid4/5/6 journal mode switching API 



Commit 2ded3703 ("md/r5cache: State machine for raid5-cache write
back mode") added support for "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 a new
r5c_journal_mode_set() API.

Use the new API in existing r5c_journal_mode_store()

Signed-off-by: default avatarHeinz Mauelshagen <heinzm@redhat.com>
Acked-by: default avatarShaohua Li <shli@fb.com>
Signed-off-by: default avatarMike Snitzer <snitzer@redhat.com>
parent ff3af92b

drivers/md/raid5-cache.c

+34 −28
Original line number Diff line number Diff line
@@ -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

drivers/md/raid5.h

+11 −0
Original line number Diff line number Diff line
@@ -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