[PATCH AUTOSEL 5.15 3/6] md: do not delete safemode_timer in mddev_suspend

[PATCH AUTOSEL 5.15 3/6] md: do not delete safemode_timer in mddev_suspend

[Sasha Levin]

From: Li Nan <linan122@huawei.com>

[ Upstream commit a8768a134518e406d41799a3594aeb74e0889cf7 ]

The deletion of safemode_timer in mddev_suspend() is redundant and
potentially harmful now. If timer is about to be woken up but gets
deleted, 'in_sync' will remain 0 until the next write, causing array
to stay in the 'active' state instead of transitioning to 'clean'.

Commit 0d9f4f135eb6 ("MD: Add del_timer_sync to mddev_suspend (fix
nasty panic))" introduced this deletion for dm, because if timer fired
after dm is destroyed, the resource which the timer depends on might
have been freed.

However, commit 0dd84b319352 ("md: call __md_stop_writes in md_stop")
added __md_stop_writes() to md_stop(), which is called before freeing
resource. Timer is deleted in __md_stop_writes(), and the origin issue
is resolved. Therefore, delete safemode_timer can be removed safely now.

Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240508092053.1447930-1-linan666@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/md.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 45ef1ddd2bd03..5b6c366587d54 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -509,7 +509,6 @@ void mddev_suspend(struct mddev *mddev)
 	clear_bit_unlock(MD_ALLOW_SB_UPDATE, &mddev->flags);
 	wait_event(mddev->sb_wait, !test_bit(MD_UPDATING_SB, &mddev->flags));
 
-	del_timer_sync(&mddev->safemode_timer);
 	/* restrict memory reclaim I/O during raid array is suspend */
 	mddev->noio_flag = memalloc_noio_save();
 }
-- 
2.43.0

[PATCH AUTOSEL 5.15 4/6] md/raid5: avoid BUG_ON() while continue reshape after reassembling

[Sasha Levin]

From: Yu Kuai <yukuai3@huawei.com>

[ Upstream commit 305a5170dc5cf3d395bb4c4e9239bca6d0b54b49 ]

Currently, mdadm support --revert-reshape to abort the reshape while
reassembling, as the test 07revert-grow. However, following BUG_ON()
can be triggerred by the test:

kernel BUG at drivers/md/raid5.c:6278!
invalid opcode: 0000 [#1] PREEMPT SMP PTI
irq event stamp: 158985
CPU: 6 PID: 891 Comm: md0_reshape Not tainted 6.9.0-03335-g7592a0b0049a #94
RIP: 0010:reshape_request+0x3f1/0xe60
Call Trace:
 <TASK>
 raid5_sync_request+0x43d/0x550
 md_do_sync+0xb7a/0x2110
 md_thread+0x294/0x2b0
 kthread+0x147/0x1c0
 ret_from_fork+0x59/0x70
 ret_from_fork_asm+0x1a/0x30
 </TASK>

Root cause is that --revert-reshape update the raid_disks from 5 to 4,
while reshape position is still set, and after reassembling the array,
reshape position will be read from super block, then during reshape the
checking of 'writepos' that is caculated by old reshape position will
fail.

Fix this panic the easy way first, by converting the BUG_ON() to
WARN_ON(), and stop the reshape if checkings fail.

Noted that mdadm must fix --revert-shape as well, and probably md/raid
should enhance metadata validation as well, however this means
reassemble will fail and there must be user tools to fix the wrong
metadata.

Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240611132251.1967786-13-yukuai1@huaweicloud.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/md/raid5.c | 20 +++++++++++++-------
 1 file changed, 13 insertions(+), 7 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index bcd43cca94f9f..87b713142e15d 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6007,7 +6007,9 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
 	safepos = conf->reshape_safe;
 	sector_div(safepos, data_disks);
 	if (mddev->reshape_backwards) {
-		BUG_ON(writepos < reshape_sectors);
+		if (WARN_ON(writepos < reshape_sectors))
+			return MaxSector;
+
 		writepos -= reshape_sectors;
 		readpos += reshape_sectors;
 		safepos += reshape_sectors;
@@ -6025,14 +6027,18 @@ static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *sk
 	 * to set 'stripe_addr' which is where we will write to.
 	 */
 	if (mddev->reshape_backwards) {
-		BUG_ON(conf->reshape_progress == 0);
+		if (WARN_ON(conf->reshape_progress == 0))
+			return MaxSector;
+
 		stripe_addr = writepos;
-		BUG_ON((mddev->dev_sectors &
-			~((sector_t)reshape_sectors - 1))
-		       - reshape_sectors - stripe_addr
-		       != sector_nr);
+		if (WARN_ON((mddev->dev_sectors &
+		    ~((sector_t)reshape_sectors - 1)) -
+		    reshape_sectors - stripe_addr != sector_nr))
+			return MaxSector;
 	} else {
-		BUG_ON(writepos != sector_nr + reshape_sectors);
+		if (WARN_ON(writepos != sector_nr + reshape_sectors))
+			return MaxSector;
+
 		stripe_addr = sector_nr;
 	}
 
-- 
2.43.0