linux-stable.git/drivers/md/raid1.c, branch v6.8.2

md/raid1: fix choose next idle in read_balance()

2024-03-26T22:16:29+00:00

[ Upstream commit 257ac239ffcfd097a9a0732bf5095fb00164f334 ]

Commit 12cee5a8a29e ("md/raid1: prevent merging too large request") add
the case choose next idle in read_balance():

read_balance:
 for_each_rdev
  if(next_seq_sect == this_sector || dist == 0)
  -> sequential reads
   best_disk = disk;
   if (...)
    choose_next_idle = 1
    continue;

 for_each_rdev
 -> iterate next rdev
  if (pending == 0)
   best_disk = disk;
   -> choose the next idle disk
   break;

  if (choose_next_idle)
   -> keep using this rdev if there are no other idle disk
   contine

However, commit 2e52d449bcec ("md/raid1: add failfast handling for reads.")
remove the code:

-               /* If device is idle, use it */
-               if (pending == 0) {
-                       best_disk = disk;
-                       break;
-               }

Hence choose next idle will never work now, fix this problem by
following:

1) don't set best_disk in this case, read_balance() will choose the best
   disk after iterating all the disks;
2) add 'pending' so that other idle disk will be chosen;
3) add a new local variable 'sequential_disk' to record the disk, and if
   there is no other idle disk, 'sequential_disk' will be chosen;

Fixes: 2e52d449bcec ("md/raid1: add failfast handling for reads.")
Co-developed-by: Paul Luse 
Signed-off-by: Paul Luse 
Signed-off-by: Yu Kuai 
Reviewed-by: Xiao Ni 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20240229095714.926789-5-yukuai1@huaweicloud.com
Signed-off-by: Sasha Levin

md/raid1: record nonrot rdevs while adding/removing rdevs to conf

2024-03-26T22:16:28+00:00

[ Upstream commit 2c27d09d3a76b33629d2e681bf8b774f776ade7f ]

For raid1, each read will iterate all the rdevs from conf and check if
any rdev is non-rotational, then choose rdev with minimal IO inflight
if so, or rdev with closest distance otherwise.

Disk nonrot info can be changed through sysfs entry:

/sys/block/[disk_name]/queue/rotational

However, consider that this should only be used for testing, and user
really shouldn't do this in real life. Record the number of non-rotational
disks in conf, to avoid checking each rdev in IO fast path and simplify
read_balance() a little bit.

Co-developed-by: Paul Luse 
Signed-off-by: Paul Luse 
Signed-off-by: Yu Kuai 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20240229095714.926789-4-yukuai1@huaweicloud.com
Stable-dep-of: 257ac239ffcf ("md/raid1: fix choose next idle in read_balance()")
Signed-off-by: Sasha Levin

md/raid1: factor out helpers to add rdev to conf

2024-03-26T22:16:28+00:00

[ Upstream commit 969d6589abcb369d53d84ec7c9c37f4b23ec1ad9 ]

There are no functional changes, just make code cleaner and prepare to
record disk non-rotational information while adding and removing rdev to
conf

Signed-off-by: Yu Kuai 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20240229095714.926789-3-yukuai1@huaweicloud.com
Stable-dep-of: 257ac239ffcf ("md/raid1: fix choose next idle in read_balance()")
Signed-off-by: Sasha Levin

md: fix a suspicious RCU usage warning

2024-01-25T06:58:00+00:00

RCU protection was removed in the commit 2d32777d60de ("raid1: remove rcu
protection to access rdev from conf").

However, the code in fix_read_error does rcu_dereference outside
rcu_read_lock - this triggers the following warning. The warning is
triggered by a LVM2 test shell/integrity-caching.sh.

This commit removes rcu_dereference.

=============================
WARNING: suspicious RCU usage
6.7.0 #2 Not tainted
-----------------------------
drivers/md/raid1.c:2265 suspicious rcu_dereference_check() usage!

other info that might help us debug this:

rcu_scheduler_active = 2, debug_locks = 1
no locks held by mdX_raid1/1859.

stack backtrace:
CPU: 2 PID: 1859 Comm: mdX_raid1 Not tainted 6.7.0 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
Call Trace:
 
 dump_stack_lvl+0x60/0x70
 lockdep_rcu_suspicious+0x153/0x1b0
 raid1d+0x1732/0x1750 [raid1]
 ? lock_acquire+0x9f/0x270
 ? finish_wait+0x3d/0x80
 ? md_thread+0xf7/0x130 [md_mod]
 ? lock_release+0xaa/0x230
 ? md_register_thread+0xd0/0xd0 [md_mod]
 md_thread+0xa0/0x130 [md_mod]
 ? housekeeping_test_cpu+0x30/0x30
 kthread+0xdc/0x110
 ? kthread_complete_and_exit+0x20/0x20
 ret_from_fork+0x28/0x40
 ? kthread_complete_and_exit+0x20/0x20
 ret_from_fork_asm+0x11/0x20
 

Signed-off-by: Mikulas Patocka 
Fixes: ca294b34aaf3 ("md/raid1: support read error check")
Reviewed-by: Yu Kuai 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/51539879-e1ca-fde3-b8b4-8934ddedcbc@redhat.com

md/raid1: Use blk_opf_t for read and write operations

2024-01-09T23:14:01+00:00

Use the type blk_opf_t for read and write operations instead of int. This
patch does not affect the generated code but fixes the following sparse
warning:

drivers/md/raid1.c:1993:60: sparse: sparse: incorrect type in argument 5 (different base types)
     expected restricted blk_opf_t [usertype] opf
     got int rw

Cc: Song Liu 
Cc: Jens Axboe 
Fixes: 3c5e514db58f ("md/raid1: Use the new blk_opf_t type")
Cc: stable@vger.kernel.org # v6.0+
Reported-by: kernel test robot 
Closes: https://lore.kernel.org/oe-kbuild-all/202401080657.UjFnvQgX-lkp@intel.com/
Signed-off-by: Bart Van Assche 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20240108001223.23835-1-bvanassche@acm.org

md/raid1: support read error check

2023-12-15T23:22:15+00:00

After commit 1e50915fe0bb ("raid: improve MD/raid10 handling of correctable
read errors."), rdev will be set to faulty if it reads data error to many
times in raid10. Add this mechanism to raid1 now.

Signed-off-by: Li Nan 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20231215023852.3478228-3-linan666@huaweicloud.com

md: factor out a helper exceed_read_errors() to check read_errors

2023-12-15T23:22:15+00:00

Move check_decay_read_errors() to raid1-10.c and factor out a helper
exceed_read_errors() to check if read_errors exceeds the limit, so that
raid1 can also use it. There are no functional changes.

Signed-off-by: Li Nan 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20231215023852.3478228-2-linan666@huaweicloud.com

md/raid1: remove unnecessary null checking

2023-12-15T08:45:37+00:00

If %__GFP_DIRECT_RECLAIM is set then bio_alloc_bioset will always
be able to allocate a bio. See comment of bio_alloc_bioset.

Signed-off-by: Gou Hao 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20231214151458.28970-1-gouhao@uniontech.com

md/raid1: remove rcu protection to access rdev from conf

2023-11-27T23:49:05+00:00

Because it's safe to accees rdev from conf:
 - If any spinlock is held, because synchronize_rcu() from
   md_kick_rdev_from_array() will prevent 'rdev' to be freed until
   spinlock is released;
 - If 'reconfig_lock' is held, because rdev can't be added or removed from
   array;
 - If there is normal IO inflight, because mddev_suspend() will prevent
   rdev to be added or removed from array;
 - If there is sync IO inflight, because 'MD_RECOVERY_RUNNING' is
   checked in remove_and_add_spares().

And these will cover all the scenarios in raid1.

Signed-off-by: Yu Kuai 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20231125081604.3939938-4-yukuai1@huaweicloud.com

md: remove flag RemoveSynchronized

2023-11-27T23:49:04+00:00

rcu is not used correctly here, because synchronize_rcu() is called
before replacing old value, for example:

remove_and_add_spares   // other path
 synchronize_rcu
 // called before replacing old value
 set_bit(RemoveSynchronized)
                        rcu_read_lock()
                        rdev = conf->mirros[].rdev
 pers->hot_remove_disk
  conf->mirros[].rdev = NULL;
  if (!test_bit(RemoveSynchronized))
   synchronize_rcu
   /*
    * won't be called, and won't wait
    * for concurrent readers to be done.
    */
                        // access rdev after remove_and_add_spares()
                        rcu_read_unlock()

Fortunately, there is a separate rcu protection to prevent such rdev
to be freed:

md_kick_rdev_from_array		//other path
				rcu_read_lock()
				rdev = conf->mirros[].rdev
list_del_rcu(&rdev->same_set)

				rcu_read_unlock()
				/*
				 * rdev can be removed from conf, but
				 * rdev won't be freed.
				 */
synchronize_rcu()
free rdev

Hence remove this useless flag and prepare to remove rcu protection to
access rdev from 'conf'.

Signed-off-by: Yu Kuai 
Signed-off-by: Song Liu 
Link: https://lore.kernel.org/r/20231125081604.3939938-2-yukuai1@huaweicloud.com