From c303fb2c28aa2afb8b3bc1905375537629317b11 Mon Sep 17 00:00:00 2001 From: Yu Kuai Date: Tue, 11 Jun 2024 21:22:51 +0800 Subject: [PATCH] md/raid5: avoid BUG_ON() while continue reshape after reassembling [ 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: 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 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 Signed-off-by: Song Liu Link: https://lore.kernel.org/r/20240611132251.1967786-13-yukuai1@huaweicloud.com Signed-off-by: Sasha Levin --- 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 ed99b449d8fd4a..4315dabd320230 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c @@ -6316,7 +6316,9 @@ 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; @@ -6334,14 +6336,18 @@ 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; }