Commit 440078db authored by Jens Axboe's avatar Jens Axboe

Merge branch 'md-fixes' of https://github.com/liu-song-6/linux into for-linus

Pull MD fix from Song.

* 'md-fixes' of https://github.com/liu-song-6/linux:
  md: fix for divide error in status_resync
parents 45691804 9642fa73
......@@ -7607,9 +7607,9 @@ static void status_unused(struct seq_file *seq)
static int status_resync(struct seq_file *seq, struct mddev *mddev)
{
sector_t max_sectors, resync, res;
unsigned long dt, db;
sector_t rt;
int scale;
unsigned long dt, db = 0;
sector_t rt, curr_mark_cnt, resync_mark_cnt;
int scale, recovery_active;
unsigned int per_milli;
if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery) ||
......@@ -7698,22 +7698,30 @@ static int status_resync(struct seq_file *seq, struct mddev *mddev)
* db: blocks written from mark until now
* rt: remaining time
*
* rt is a sector_t, so could be 32bit or 64bit.
* So we divide before multiply in case it is 32bit and close
* to the limit.
* We scale the divisor (db) by 32 to avoid losing precision
* near the end of resync when the number of remaining sectors
* is close to 'db'.
* We then divide rt by 32 after multiplying by db to compensate.
* The '+1' avoids division by zero if db is very small.
* rt is a sector_t, which is always 64bit now. We are keeping
* the original algorithm, but it is not really necessary.
*
* Original algorithm:
* So we divide before multiply in case it is 32bit and close
* to the limit.
* We scale the divisor (db) by 32 to avoid losing precision
* near the end of resync when the number of remaining sectors
* is close to 'db'.
* We then divide rt by 32 after multiplying by db to compensate.
* The '+1' avoids division by zero if db is very small.
*/
dt = ((jiffies - mddev->resync_mark) / HZ);
if (!dt) dt++;
db = (mddev->curr_mark_cnt - atomic_read(&mddev->recovery_active))
- mddev->resync_mark_cnt;
curr_mark_cnt = mddev->curr_mark_cnt;
recovery_active = atomic_read(&mddev->recovery_active);
resync_mark_cnt = mddev->resync_mark_cnt;
if (curr_mark_cnt >= (recovery_active + resync_mark_cnt))
db = curr_mark_cnt - (recovery_active + resync_mark_cnt);
rt = max_sectors - resync; /* number of remaining sectors */
sector_div(rt, db/32+1);
rt = div64_u64(rt, db/32+1);
rt *= dt;
rt >>= 5;
......
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