[RFC PATCH 4/7] Increment diskseq when releasing a loop device

Demi Marie Obenour
2023-01-26T03:34:25Z

This ensures that userspace is aware that the device may now point to
something else.

Signed-off-by: Demi Marie Obenour <demi@invisiblethingslab.com>
---
block/genhd.c | 1 +
drivers/block/loop.c | 6 ++++++
2 files changed, 7 insertions(+)

diff --git a/block/genhd.c b/block/genhd.c
index 23cf83b3331cdea5c916fbf01cb5b92aeb2f7cf8..5bf7664273c66d04b40730434f17f7b65fbfe101 100644
--- a/block/genhd.c
+++ b/block/genhd.c
@@ -1490,3 +1490,4 @@ void inc_diskseq(struct gendisk *disk)
{
disk->diskseq = atomic64_inc_return(&diskseq);
}
+EXPORT_SYMBOL(inc_diskseq);
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 1518a6423279bc890221e8184a8f2e420cb16715..f862b0ab1dce43b3617b1381be8e2de3aab828b1 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1205,6 +1205,12 @@ static void __loop_clr_fd(struct loop_device *lo, bool release)
if (!part_shift)
set_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
mutex_lock(&lo->lo_mutex);
+
+ /*
+ * Increment the disk sequence number, so that userspace knows this
+ * device now points to something else.
+ */
+ inc_diskseq(lo->lo_disk);
lo->lo_state = Lo_unbound;
mutex_unlock(&lo->lo_mutex);