[lkml]   [2018]   [Mar]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
Patch in this message
Subject[PATCH 4.4 34/36] dm io: fix duplicate bio completion due to missing ref count
4.4-stable review patch.  If anyone has any objections, please let me know.


From: Mike Snitzer <>

commit feb7695fe9fb83084aa29de0094774f4c9d4c9fc upstream.

If only a subset of the devices associated with multiple regions support
a given special operation (eg. DISCARD) then the dec_count() that is
used to set error for the region must increment the io->count.

Otherwise, when the dec_count() is called it can cause the dm-io
caller's bio to be completed multiple times. As was reported against
the dm-mirror target that had mirror legs with a mix of discard

Reported-by: Zhang Yi <>
Signed-off-by: Mike Snitzer <>
Signed-off-by: Greg Kroah-Hartman <>

drivers/md/dm-io.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -300,6 +300,7 @@ static void do_region(int rw, unsigned r
else if (rw & REQ_WRITE_SAME)
special_cmd_max_sectors = q->limits.max_write_same_sectors;
if ((rw & (REQ_DISCARD | REQ_WRITE_SAME)) && special_cmd_max_sectors == 0) {
+ atomic_inc(&io->count);
dec_count(io, region, -EOPNOTSUPP);

 \ /
  Last update: 2018-03-10 01:44    [W:0.581 / U:2.608 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site