diff options
author | Mariusz Tkaczyk <mariusz.tkaczyk@intel.com> | 2019-06-13 16:11:41 +0200 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-07-21 09:04:26 +0200 |
commit | a113e3324cded82bfeba4ef84d85ad9b0831f6df (patch) | |
tree | a4a1f5d9bfa2fee9f6e46d67a45551f10d92ebf0 /drivers/md | |
parent | 065cf4159258caf507d96fa5449c601e5a9e865a (diff) |
md: fix for divide error in status_resync
[ Upstream commit 9642fa73d073527b0cbc337cc17a47d545d82cd2 ]
Stopping external metadata arrays during resync/recovery causes
retries, loop of interrupting and starting reconstruction, until it
hit at good moment to stop completely. While these retries
curr_mark_cnt can be small- especially on HDD drives, so subtraction
result can be smaller than 0. However it is casted to uint without
checking. As a result of it the status bar in /proc/mdstat while stopping
is strange (it jumps between 0% and 99%).
The real problem occurs here after commit 72deb455b5ec ("block: remove
CONFIG_LBDAF"). Sector_div() macro has been changed, now the
divisor is casted to uint32. For db = -8 the divisior(db/32-1) becomes 0.
Check if db value can be really counted and replace these macro by
div64_u64() inline.
Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@intel.com>
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/md')
-rw-r--r-- | drivers/md/md.c | 36 |
1 files changed, 22 insertions, 14 deletions
diff --git a/drivers/md/md.c b/drivers/md/md.c index b27a69388dcd..764ed9c46629 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7605,9 +7605,9 @@ 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) || @@ -7677,22 +7677,30 @@ 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; |