[LTP] Patch "loop: Fix occasional uevent drop" has been added to the 5.9-stable tree

[gregkh@linuxfoundation.org <gregkh@linuxfoundation.org>]

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

    loop: Fix occasional uevent drop

to the 5.9-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:
     loop-fix-occasional-uevent-drop.patch
and it can be found in the queue-5.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


From c01a21b77722db0474bbcc4eafc8c4e0d8fed6d8 Mon Sep 17 00:00:00 2001
From: Petr Vorel <pvorel@suse.cz>
Date: Thu, 12 Nov 2020 17:50:05 +0100
Subject: loop: Fix occasional uevent drop

From: Petr Vorel <pvorel@suse.cz>

commit c01a21b77722db0474bbcc4eafc8c4e0d8fed6d8 upstream.

Commit 716ad0986cbd ("loop: Switch to set_capacity_revalidate_and_notify")
causes an occasional drop of loop device uevent, which are no longer
triggered in loop_set_size() but in a different part of code.

Bug is reproducible with LTP test uevent01 [1]:

i=0; while true; do
    i=$((i+1)); echo "== $i =="
    lsmod |grep -q loop && rmmod -f loop
    ./uevent01 || break
done

Put back triggering through code called in loop_set_size().

Fix required to add yet another parameter to
set_capacity_revalidate_and_notify().

[1] https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/uevents/uevent01.c

[hch: rebased on a different change to the prototype of
 set_capacity_revalidate_and_notify]

Cc: stable@vger.kernel.org # v5.9
Fixes: 716ad0986cbd ("loop: Switch to set_capacity_revalidate_and_notify")
Reported-by: <ltp@lists.linux.it>
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/block/loop.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -255,7 +255,8 @@ static void loop_set_size(struct loop_de
 
 	bd_set_size(bdev, size << SECTOR_SHIFT);
 
-	set_capacity_revalidate_and_notify(lo->lo_disk, size, false);
+	if (!set_capacity_revalidate_and_notify(lo->lo_disk, size, false))
+		kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
 }
 
 static inline int


Patches currently in stable-queue which might be from pvorel@suse.cz are

queue-5.9/block-add-a-return-value-to-set_capacity_revalidate_and_notify.patch
queue-5.9/loop-fix-occasional-uevent-drop.patch