On 03/28/2017 02:22 AM, Shaohua Li wrote:

On Mon, Mar 27, 2017 at 03:52:25PM +0800, Zhilong Liu wrote:

quoted

This is a bug about array cannot be opened again after 'md_set_readonly',
because the MD_CLOSING bit is still waiting for clear.
MD_CLOSING should only be set for a short period or time to avoid certain
races. After the operation that set it completes, it should be cleared.

where is the bit set? Why don't clear it after the operation but clear it in
set_readonly?
  

it goes two paths after set MD_CLOSING bit, do_md_stop and md_set_readonly,
the do_md_stop has done the md_clean to clear the mddev->flags, thus I 
put it in
md_set_readonly.
Thanks for your suggestion, is the following changing good for you? here 
it has
finished what it needs to do, so clear the MD_CLOSING bit in time.
if looks good, I would send this in new revision patch.

diff --git a/drivers/md/md.c b/drivers/md/md.c
index f6ae1d6..e8c1130 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -6868,6 +6868,7 @@ static int md_ioctl(struct block_device *bdev, 

fmode_t mode,
                 set_bit(MD_CLOSING, &mddev->flags);
                 mutex_unlock(&mddev->open_mutex);
                 sync_blockdev(bdev);
+               clear_bit(MD_CLOSING, &mddev->flags);
         }
         err = mddev_lock(mddev);
         if (err) {

Thanks,
-Zhilong

quoted

Reviewed-by: NeilBrown <redacted>
Cc: Guoqing Jiang <redacted>
Signed-off-by: Zhilong Liu <redacted>
---
  drivers/md/md.c | 1 +
  1 file changed, 1 insertion(+)

diff --git a/drivers/md/md.c b/drivers/md/md.c
index f6ae1d6..7f2db7c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c

@@ -5588,6 +5588,7 @@ static int md_set_readonly(struct mddev *mddev, struct block_device *bdev)
  	int err = 0;
  	int did_freeze = 0;
  
+	test_and_clear_bit(MD_CLOSING, &mddev->flags);

I don't understand why this must be a test_and_clear.

Thanks,
Shaohua
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