3.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: NeilBrown <neilb@xxxxxxx>
commit 2f73d3c55d09ce60647b96ad2a9b539c95a530ee upstream.
The resync/recovery process for raid1 was recently changed
so that writes could happen in parallel with resync providing
they were in different regions of the device.
There is a problem though: While a write request will always
wait for conflicting resync to complete, a resync request
will *not* always wait for conflicting writes to complete.
Two changes are needed to fix this:
1/ raise_barrier (which waits until it is safe to do resync)
must wait until current_window_requests is zero
2/ wait_battier (which waits at the start of a new write request)
must update current_window_requests if the request could
possible conflict with a concurrent resync.
As concurrent writes and resync can lead to data loss,
this patch is suitable for -stable.
Fixes: 79ef3a8aa1cb1523cc231c9a90a278333c21f761
Cc: majianpeng <majianpeng@xxxxxxxxx>
Signed-off-by: NeilBrown <neilb@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/md/raid1.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/md/raid1.c
+++ b/drivers/md/raid1.c
@@ -845,10 +845,12 @@ static void raise_barrier(struct r1conf
* C: next_resync + RESYNC_SECTORS > start_next_window, meaning
* next resync will reach to the window which normal bios are
* handling.
+ * D: while there are any active requests in the current window.
*/
wait_event_lock_irq(conf->wait_barrier,
!conf->array_frozen &&
conf->barrier < RESYNC_DEPTH &&
+ conf->current_window_requests == 0 &&
(conf->start_next_window >=
conf->next_resync + RESYNC_SECTORS),
conf->resync_lock);
@@ -915,8 +917,8 @@ static sector_t wait_barrier(struct r1co
}
if (bio && bio_data_dir(bio) == WRITE) {
- if (conf->next_resync + NEXT_NORMALIO_DISTANCE
- <= bio->bi_iter.bi_sector) {
+ if (bio->bi_iter.bi_sector >=
+ conf->next_resync) {
if (conf->start_next_window == MaxSector)
conf->start_next_window =
conf->next_resync +
--
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