This is a note to let you know that I've just added the patch titled

    dm-raid: add a new helper prepare_suspend() in md_personality

to the 6.7-stable tree which can be found at:
    
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     dm-raid-add-a-new-helper-prepare_suspend-in-md_perso.patch
and it can be found in the queue-6.7 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.



commit 2eea0920d6a4eec9ef6bf65a03cc3a32bb1fb44e
Author: Yu Kuai <[email protected]>
Date:   Tue Mar 5 15:23:04 2024 +0800

    dm-raid: add a new helper prepare_suspend() in md_personality
    
    [ Upstream commit 5625ff8b72b0e5c13b0fc1fc1f198155af45f729 ]
    
    There are no functional changes for now, prepare to fix a deadlock for
    dm-raid456.
    
    Cc: [email protected] # v6.7+
    Signed-off-by: Yu Kuai <[email protected]>
    Signed-off-by: Xiao Ni <[email protected]>
    Acked-by: Mike Snitzer <[email protected]>
    Signed-off-by: Song Liu <[email protected]>
    Link: 
https://lore.kernel.org/r/[email protected]
    Signed-off-by: Sasha Levin <[email protected]>

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index 8d38cdb221453..b8f5304ca00d1 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -3803,6 +3803,23 @@ static void raid_io_hints(struct dm_target *ti, struct 
queue_limits *limits)
        blk_limits_io_opt(limits, chunk_size_bytes * mddev_data_stripes(rs));
 }
 
+static void raid_presuspend(struct dm_target *ti)
+{
+       struct raid_set *rs = ti->private;
+       struct mddev *mddev = &rs->md;
+
+       if (!reshape_interrupted(mddev))
+               return;
+
+       /*
+        * For raid456, if reshape is interrupted, IO across reshape position
+        * will never make progress, while caller will wait for IO to be done.
+        * Inform raid456 to handle those IO to prevent deadlock.
+        */
+       if (mddev->pers && mddev->pers->prepare_suspend)
+               mddev->pers->prepare_suspend(mddev);
+}
+
 static void raid_postsuspend(struct dm_target *ti)
 {
        struct raid_set *rs = ti->private;
@@ -4087,6 +4104,7 @@ static struct target_type raid_target = {
        .message = raid_message,
        .iterate_devices = raid_iterate_devices,
        .io_hints = raid_io_hints,
+       .presuspend = raid_presuspend,
        .postsuspend = raid_postsuspend,
        .preresume = raid_preresume,
        .resume = raid_resume,
diff --git a/drivers/md/md.h b/drivers/md/md.h
index ea0fd76c17e75..24261f9b676d5 100644
--- a/drivers/md/md.h
+++ b/drivers/md/md.h
@@ -649,6 +649,7 @@ struct md_personality
        int (*start_reshape) (struct mddev *mddev);
        void (*finish_reshape) (struct mddev *mddev);
        void (*update_reshape_pos) (struct mddev *mddev);
+       void (*prepare_suspend) (struct mddev *mddev);
        /* quiesce suspends or resumes internal processing.
         * 1 - stop new actions and wait for action io to complete
         * 0 - return to normal behaviour

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