3.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Mike Snitzer <snit...@redhat.com>
commit 7ba10aa6fbac7158a50bec142132b04bc480bb29 upstream.
When there are no paths and multipath receives an ioctl, it waits until
a path becomes available. This behaviour is incorrect if the
"queue_if_no_path" setting was not specified, as then the ioctl should
be rejected immediately, which this patch now does.
commit 35991652b ("dm mpath: allow ioctls to trigger pg init") should
have checked if queue_if_no_path was configured before queueing IO.
Checking for the queue_if_no_path feature, like is done in map_io(),
allows the following table load to work without blocking in the
multipath_ioctl retry loop:
echo "0 1024 multipath 0 0 0 0" | dmsetup create mpath_nodevs
Without this fix the multipath_ioctl will block with the following stack
trace:
blkid D 0000000000000002 0 23936 1 0x00000000
ffff8802b89e5cd8 0000000000000082 ffff8802b89e5fd8 0000000000012440
ffff8802b89e4010 0000000000012440 0000000000012440 0000000000012440
ffff8802b89e5fd8 0000000000012440 ffff88030c2aab30 ffff880325794040
Call Trace:
[<ffffffff814ce099>] schedule+0x29/0x70
[<ffffffff814cc312>] schedule_timeout+0x182/0x2e0
[<ffffffff8104dee0>] ? lock_timer_base+0x70/0x70
[<ffffffff814cc48e>] schedule_timeout_uninterruptible+0x1e/0x20
[<ffffffff8104f840>] msleep+0x20/0x30
[<ffffffffa0000839>] multipath_ioctl+0x109/0x170 [dm_multipath]
[<ffffffffa06bfb9c>] dm_blk_ioctl+0xbc/0xd0 [dm_mod]
[<ffffffff8122a408>] __blkdev_driver_ioctl+0x28/0x30
[<ffffffff8122a79e>] blkdev_ioctl+0xce/0x730
[<ffffffff811970ac>] block_ioctl+0x3c/0x40
[<ffffffff8117321c>] do_vfs_ioctl+0x8c/0x340
[<ffffffff81166293>] ? sys_newfstat+0x33/0x40
[<ffffffff81173571>] sys_ioctl+0xa1/0xb0
[<ffffffff814d70a9>] system_call_fastpath+0x16/0x1b
Signed-off-by: Mike Snitzer <snit...@redhat.com>
Acked-by: Mikulas Patocka <mpato...@redhat.com>
Signed-off-by: Alasdair G Kergon <a...@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
drivers/md/dm-mpath.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
--- a/drivers/md/dm-mpath.c
+++ b/drivers/md/dm-mpath.c
@@ -1520,6 +1520,7 @@ static int multipath_ioctl(struct dm_tar
unsigned long arg)
{
struct multipath *m = ti->private;
+ struct pgpath *pgpath;
struct block_device *bdev;
fmode_t mode;
unsigned long flags;
@@ -1535,12 +1536,14 @@ again:
if (!m->current_pgpath)
__choose_pgpath(m, 0);
- if (m->current_pgpath) {
- bdev = m->current_pgpath->path.dev->bdev;
- mode = m->current_pgpath->path.dev->mode;
+ pgpath = m->current_pgpath;
+
+ if (pgpath) {
+ bdev = pgpath->path.dev->bdev;
+ mode = pgpath->path.dev->mode;
}
- if (m->queue_io)
+ if ((pgpath && m->queue_io) || (!pgpath && m->queue_if_no_path))
r = -EAGAIN;
else if (!bdev)
r = -EIO;
--
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