On Wed, Feb 1, 2023 at 4:51 PM Hou Tao [off-list ref] wrote:

Hi,

On 2/2/2023 12:35 AM, Song Liu wrote:

quoted

On Mon, Jan 30, 2023 at 10:39 PM Hou Tao [off-list ref] wrote:

quoted

From: Hou Tao <redacted>

Don't update recovery_cp when curr_resync is MD_RESYNC_ACTIVE, otherwise
md may skip the resync of the first 3 sectors if the resync procedure is
interrupted before the first calling of ->sync_request() as shown below:

md_do_sync thread          control thread
  // setup resync
  mddev->recovery_cp = 0
  j = 0
  mddev->curr_resync = MD_RESYNC_ACTIVE

                             // e.g., set array as idle
                             set_bit(MD_RECOVERY_INTR, &&mddev_recovery)
  // resync loop
  // check INTR before calling sync_request
  !test_bit(MD_RECOVERY_INTR, &mddev->recovery

  // resync interrupted
  // update recovery_cp from 0 to 3
  // the resync of three 3 sectors will be skipped
  mddev->recovery_cp = 3

Fixes: eac58d08d493 ("md: Use enum for overloaded magic numbers used by mddev->curr_resync")
Signed-off-by: Hou Tao <redacted>

By the way, how did you find this issue? Is it from users/production?
Or just from reading the code?

Found the issue when reading the code and reproduced the problem to confirm that.

Thanks for the information!

Song