From: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
Call chain md_run() -> md_bitmap_create() in the target's constructor reads the bitmap
superblock thus overwriting any set rs->md.bitmap_info.max_write_behind. In order to
make such set writebehind value persistent, save/restore its value around the md_run() call.
As the MD bitmap code uses the writebehind numeral as the maximum number of delayed writes
to any writemostly component device(s) in a RAID1 array, avoid falsely dividing it by 2 and
correct comment accordingly.
Signed-off-by: Heinz Mauelshagen <heinzm@xxxxxxxxxx>
---
drivers/md/dm-raid.c | 20 +++++++++++++-------
1 file changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index becdb689190e..32d55210ea0c 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -1111,7 +1111,7 @@ static int validate_raid_redundancy(struct raid_set *rs)
* [min_recovery_rate <kB/sec/disk>] Throttle RAID initialization
* [max_recovery_rate <kB/sec/disk>] Throttle RAID initialization
* [write_mostly <idx>] Indicate a write mostly drive via index
- * [max_write_behind <sectors>] See '-write-behind=' (man mdadm)
+ * [max_write_behind <#writes>] See '--write-behind=' (man mdadm)
* [stripe_cache <sectors>] Stripe cache size for higher RAIDs
* [region_size <sectors>] Defines granularity of bitmap
* [journal_dev <dev>] raid4/5/6 journaling deviice
@@ -1349,16 +1349,13 @@ static int parse_raid_params(struct raid_set *rs, struct dm_arg_set *as,
return -EINVAL;
}
- /*
- * In device-mapper, we specify things in sectors, but
- * MD records this value in kB
- */
- if (value < 0 || value / 2 > COUNTER_MAX) {
+ /* Check for MD maximum. */
+ if (!__within_range(value, 0, COUNTER_MAX)) {
rs->ti->error = "Max write-behind limit out of range";
return -EINVAL;
}
- rs->md.bitmap_info.max_write_behind = value / 2;
+ rs->md.bitmap_info.max_write_behind = value;
} else if (!strcasecmp(key, dm_raid_arg_name_by_flag(CTR_FLAG_DAEMON_SLEEP))) {
if (test_and_set_bit(__CTR_FLAG_DAEMON_SLEEP, &rs->ctr_flags)) {
rs->ti->error = "Only one daemon_sleep argument pair allowed";
@@ -2997,6 +2994,7 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
bool resize = false;
struct raid_type *rt;
unsigned int num_raid_params, num_raid_devs;
+ unsigned long max_write_behind;
sector_t sb_array_sectors, rdev_sectors, reshape_sectors;
struct raid_set *rs = NULL;
const char *arg;
@@ -3238,6 +3236,10 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
/* Keep array frozen until resume. */
set_bit(MD_RECOVERY_FROZEN, &rs->md.recovery);
+ /* Memorize max_write_behind as it does not stick in md_bitmap_create() */
+ if (test_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags))
+ max_write_behind = rs->md.bitmap_info.max_write_behind;
+
/* Has to be held on running the array */
mddev_lock_nointr(&rs->md);
r = md_run(&rs->md);
@@ -3248,6 +3250,10 @@ static int raid_ctr(struct dm_target *ti, unsigned int argc, char **argv)
goto bad;
}
+ /* Now define max_write_behind. */
+ if (test_bit(__CTR_FLAG_MAX_WRITE_BEHIND, &rs->ctr_flags))
+ rs->md.bitmap_info.max_write_behind = max_write_behind;
+
r = md_start(&rs->md);
if (r) {
ti->error = "Failed to start raid array";
--
2.41.0
--
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