linux-stable.git/drivers/md/raid10.c, branch v5.3

md/raid10: read balance chooses idlest disk for SSD

2019-06-15T07:37:35+00:00

Andy reported that raid10 array with SSD disks has poor
read performance. Compared with raid1, RAID-1 can be 3x
faster than RAID-10 sometimes [1].

The thing is that raid10 chooses the low distance disk
for read request, however, the approach doesn't work
well for SSD device since it doesn't have spindle like
HDD, we should just read from the SSD which has less
pending IO like commit 9dedf60313fa4 ("md/raid1: read
balance chooses idlest disk for SSD").

So this commit selects the idlest SSD disk for read if
array has none rotational disk, otherwise, read_balance
uses the previous distance priority algorithm. With the
change, the performance of raid10 gets increased largely
per Andy's test [2].

[1]. https://marc.info/?l=linux-raid&m=155915890004761&w=2
[2]. https://marc.info/?l=linux-raid&m=155990654223786&w=2

Tested-by: Andy Smith 
Signed-off-by: Guoqing Jiang 
Signed-off-by: Song Liu 
Signed-off-by: Jens Axboe

md: raid1-10: Unify r{1,10}bio_pool_free

2019-06-15T07:37:35+00:00

Avoiding duplicated code, since they just execute a kfree.

Signed-off-by: Marcos Paulo de Souza 
Signed-off-by: Jens Axboe

md: raid10: Use struct_size() in kmalloc()

2019-06-15T07:37:34+00:00

One of the more common cases of allocation size calculations is finding
the size of a structure that has a zero-sized array at the end, along
with memory for some number of elements for that array. For example:

struct foo {
   int stuff;
   struct boo entry[];
};

instance = kmalloc(size, GFP_KERNEL);

Instead of leaving these open-coded and prone to type mistakes, we can
now use the new struct_size() helper:

instance = kmalloc(struct_size(instance, entry, count), GFP_KERNEL);

This code was detected with the help of Coccinelle.

Signed-off-by: Gustavo A. R. Silva 
Signed-off-by: Song Liu 
Signed-off-by: Jens Axboe

drivers: md: Unify common definitions of raid1 and raid10

2019-06-15T07:37:34+00:00

These definitions are being moved to raid1-10.c.

Signed-off-by: Marcos Paulo de Souza 
Signed-off-by: Song Liu 
Signed-off-by: Jens Axboe

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 47

2019-05-24T15:27:13+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 or at your option any
  later version you should have received a copy of the gnu general
  public license for example usr src linux copying if not write to the
  free software foundation inc 675 mass ave cambridge ma 02139 usa

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 20 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Reviewed-by: Kate Stewart 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190520170858.552543146@linutronix.de
Signed-off-by: Greg Kroah-Hartman

md: Fix failed allocation of md_register_thread

2019-03-12T17:15:18+00:00

mddev->sync_thread can be set to NULL on kzalloc failure downstream.
The patch checks for such a scenario and frees allocated resources.

Committer node:

Added similar fix to raid5.c, as suggested by Guoqing.

Cc: stable@vger.kernel.org # v3.16+
Acked-by: Guoqing Jiang 
Signed-off-by: Aditya Pakki 
Signed-off-by: Song Liu

It's wrong to add len to sector_nr in raid10 reshape twice

2019-03-12T17:15:18+00:00

In reshape_request it already adds len to sector_nr already. It's wrong to add len to
sector_nr again after adding pages to bio. If there is bad block it can't copy one chunk
at a time, it needs to goto read_more. Now the sector_nr is wrong. It can cause data
corruption.

Cc: stable@vger.kernel.org # v3.16+
Signed-off-by: Xiao Ni 
Signed-off-by: Song Liu

md: fix raid10 hang issue caused by barrier

2018-12-20T16:53:24+00:00

When both regular IO and resync IO happen at the same time,
and if we also need to split regular. Then we can see tasks
hang due to barrier.

1. resync thread
[ 1463.757205] INFO: task md1_resync:5215 blocked for more than 480 seconds.
[ 1463.757207]       Not tainted 4.19.5-1-default #1
[ 1463.757209] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1463.757212] md1_resync      D    0  5215      2 0x80000000
[ 1463.757216] Call Trace:
[ 1463.757223]  ? __schedule+0x29a/0x880
[ 1463.757231]  ? raise_barrier+0x8d/0x140 [raid10]
[ 1463.757236]  schedule+0x78/0x110
[ 1463.757243]  raise_barrier+0x8d/0x140 [raid10]
[ 1463.757248]  ? wait_woken+0x80/0x80
[ 1463.757257]  raid10_sync_request+0x1f6/0x1e30 [raid10]
[ 1463.757265]  ? _raw_spin_unlock_irq+0x22/0x40
[ 1463.757284]  ? is_mddev_idle+0x125/0x137 [md_mod]
[ 1463.757302]  md_do_sync.cold.78+0x404/0x969 [md_mod]
[ 1463.757311]  ? wait_woken+0x80/0x80
[ 1463.757336]  ? md_rdev_init+0xb0/0xb0 [md_mod]
[ 1463.757351]  md_thread+0xe9/0x140 [md_mod]
[ 1463.757358]  ? _raw_spin_unlock_irqrestore+0x2e/0x60
[ 1463.757364]  ? __kthread_parkme+0x4c/0x70
[ 1463.757369]  kthread+0x112/0x130
[ 1463.757374]  ? kthread_create_worker_on_cpu+0x40/0x40
[ 1463.757380]  ret_from_fork+0x3a/0x50

2. regular IO
[ 1463.760679] INFO: task kworker/0:8:5367 blocked for more than 480 seconds.
[ 1463.760683]       Not tainted 4.19.5-1-default #1
[ 1463.760684] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 1463.760687] kworker/0:8     D    0  5367      2 0x80000000
[ 1463.760718] Workqueue: md submit_flushes [md_mod]
[ 1463.760721] Call Trace:
[ 1463.760731]  ? __schedule+0x29a/0x880
[ 1463.760741]  ? wait_barrier+0xdd/0x170 [raid10]
[ 1463.760746]  schedule+0x78/0x110
[ 1463.760753]  wait_barrier+0xdd/0x170 [raid10]
[ 1463.760761]  ? wait_woken+0x80/0x80
[ 1463.760768]  raid10_write_request+0xf2/0x900 [raid10]
[ 1463.760774]  ? wait_woken+0x80/0x80
[ 1463.760778]  ? mempool_alloc+0x55/0x160
[ 1463.760795]  ? md_write_start+0xa9/0x270 [md_mod]
[ 1463.760801]  ? try_to_wake_up+0x44/0x470
[ 1463.760810]  raid10_make_request+0xc1/0x120 [raid10]
[ 1463.760816]  ? wait_woken+0x80/0x80
[ 1463.760831]  md_handle_request+0x121/0x190 [md_mod]
[ 1463.760851]  md_make_request+0x78/0x190 [md_mod]
[ 1463.760860]  generic_make_request+0x1c6/0x470
[ 1463.760870]  raid10_write_request+0x77a/0x900 [raid10]
[ 1463.760875]  ? wait_woken+0x80/0x80
[ 1463.760879]  ? mempool_alloc+0x55/0x160
[ 1463.760895]  ? md_write_start+0xa9/0x270 [md_mod]
[ 1463.760904]  raid10_make_request+0xc1/0x120 [raid10]
[ 1463.760910]  ? wait_woken+0x80/0x80
[ 1463.760926]  md_handle_request+0x121/0x190 [md_mod]
[ 1463.760931]  ? _raw_spin_unlock_irq+0x22/0x40
[ 1463.760936]  ? finish_task_switch+0x74/0x260
[ 1463.760954]  submit_flushes+0x21/0x40 [md_mod]

So resync io is waiting for regular write io to complete to
decrease nr_pending (conf->barrier++ is called before waiting).
The regular write io splits another bio after call wait_barrier
which call nr_pending++, then the splitted bio would continue
with raid10_write_request -> wait_barrier, so the splitted bio
has to wait for barrier to be zero, then deadlock happens as
follows.

	resync io		regular io

	raise_barrier
				wait_barrier
				generic_make_request
				wait_barrier

To resolve the issue, we need to call allow_barrier to decrease
nr_pending before generic_make_request since regular IO is not
issued to underlying devices, and wait_barrier is called again
to ensure no internal IO happening.

Fixes: fc9977dd069e ("md/raid10: simplify the splitting of requests.")
Reported-and-tested-by: Siniša Bandin 
Signed-off-by: Guoqing Jiang 
Signed-off-by: Shaohua Li

raid10: refactor common wait code from regular read/write request

2018-12-20T16:53:24+00:00

Both raid10_read_request and raid10_write_request share
the same code at the beginning of them, so introduce
regular_request_wait to clean up code, and call it in
both request functions.

Signed-off-by: Guoqing Jiang 
Signed-off-by: Shaohua Li

md-cluster: introduce resync_info_get interface for sanity check

2018-10-18T16:36:35+00:00

Since the resync region from suspend_info means one node
is reshaping this area, so the position of reshape_progress
should be included in the area.

Reviewed-by: NeilBrown 
Signed-off-by: Guoqing Jiang 
Signed-off-by: Shaohua Li