diff mbox series

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

Message ID 20230126033358.1880-5-demi@invisiblethingslab.com
State New
Headers
Series Allow race-free block device handling |

Commit Message

Demi Marie Obenour Jan. 26, 2023, 3:33 a.m. UTC 
  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(+)

Comments

Christoph Hellwig Jan. 30, 2023, 8:09 a.m. UTC | #1 
On Wed, Jan 25, 2023 at 10:33:56PM -0500, Demi Marie Obenour wrote:
> This ensures that userspace is aware that the device may now point to
> something else.

The subject is wong, this also does two things to two different
subystems, not of which is mentioned in the subject.
diff mbox series

Patch

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);