Re: [PATCH v4 1/4] md: Don't clear MD_CLOSING when the raid is about to stop

From: Yu Kuai
Date: Sat Jan 27 2024 - 03:38:19 EST


Hi,

在 2024/01/26 17:22, linan666@xxxxxxxxxxxxxxx 写道:
From: Li Nan <linan122@xxxxxxxxxx>

The raid should not be opened anymore when it is about to be stopped.
However, other processes can open it again if the flag MD_CLOSING is
cleared before exiting. From now on, this flag will not be cleared when
the raid will be stopped.

This patch looks good, just one nit below:

Fixes: 065e519e71b2 ("md: MD_CLOSING needs to be cleared after called md_set_readonly or do_md_stop")
Signed-off-by: Li Nan <linan122@xxxxxxxxxx>
Acked-by: Mariusz Tkaczyk <mariusz.tkaczyk@xxxxxxxxxxxxxxx>
---
drivers/md/md.c | 22 ++++++++++++++++++----
1 file changed, 18 insertions(+), 4 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 9bdd57324c37..06550fe34aa1 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6254,7 +6254,15 @@ static void md_clean(struct mddev *mddev)
mddev->persistent = 0;
mddev->level = LEVEL_NONE;
mddev->clevel[0] = 0;
- mddev->flags = 0;
+ /*
+ * Don't clear MD_CLOSING, or mddev can be opened again.
+ * 'hold_active != 0' means mddev is still in the creation
+ * process and will be used later.
+ */
+ if (mddev->hold_active)
+ mddev->flags = 0;
+ else
+ mddev->flags &= BIT_ULL_MASK(MD_CLOSING);
mddev->sb_flags = 0;
mddev->ro = MD_RDWR;
mddev->metadata_type[0] = 0;
@@ -7600,7 +7608,7 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
int err = 0;
void __user *argp = (void __user *)arg;
struct mddev *mddev = NULL;
- bool did_set_md_closing = false;
+ bool clear_md_closing = false;
if (!md_ioctl_valid(cmd))
return -ENOTTY;
@@ -7684,7 +7692,7 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
err = -EBUSY;
goto out;
}
- did_set_md_closing = true;
+ clear_md_closing = true;
mutex_unlock(&mddev->open_mutex);
sync_blockdev(bdev);
}
@@ -7728,6 +7736,12 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
case STOP_ARRAY:
err = do_md_stop(mddev, 0, bdev);
+ if (!err)
+ /*
+ * mddev has been stopped, keep the flag
+ * MD_CLOSING to prevent reuse.
+ */
+ clear_md_closing = false;
goto unlock;
case STOP_ARRAY_RO:
@@ -7826,7 +7840,7 @@ static int md_ioctl(struct block_device *bdev, blk_mode_t mode,
mddev_unlock(mddev);
out:
- if(did_set_md_closing)
+ if (clear_md_closing)

I think code will be simplier if we just remove this local variable, and
replace this with:
if (test_bit(MD_CLOSING, &mddev->flags) && (err || cmd == STOP_ARRAY_RO))

And the same for patch 3.

Thanks,
Kuai

clear_bit(MD_CLOSING, &mddev->flags);
return err;
}