From: Alyssa Ross <hi@xxxxxxxxx>
LOOP_CONFIGURE is, as far as I understand it, supposed to be a way to
combine LOOP_SET_FD and LOOP_SET_STATUS64 into a single syscall. When
using LOOP_SET_FD+LOOP_SET_STATUS64, a single uevent would be sent for
each partition found on the loop device after the second ioctl(), but
when using LOOP_CONFIGURE, no such uevent was being sent.
In the old setup, uevents are disabled for LOOP_SET_FD, but not for
LOOP_SET_STATUS64. This makes sense, as it prevents uevents being
sent for a partially configured device during LOOP_SET_FD - they're
only sent at the end of LOOP_SET_STATUS64. But for LOOP_CONFIGURE,
uevents were disabled for the entire operation, so that final
notification was never issued. To fix this, reduce the critical
section to exclude the loop_reread_partitions() call, which causes
the uevents to be issued, to after uevents are re-enabled, matching
the behaviour of the LOOP_SET_FD+LOOP_SET_STATUS64 combination.
I noticed this because Busybox's losetup program recently changed from
using LOOP_SET_FD+LOOP_SET_STATUS64 to LOOP_CONFIGURE, and this broke
my setup, for which I want a notification from the kernel any time a
new partition becomes available.
Signed-off-by: Alyssa Ross <hi@xxxxxxxxx>
[hch: reduced the critical section]
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Fixes: 3448914e8cc5 ("loop: Add LOOP_CONFIGURE ioctl")
---
drivers/block/loop.c | 18 +++++++++---------
1 file changed, 9 insertions(+), 9 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 839373451c2b7d..9d61c027185141 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1010,9 +1010,6 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
/* This is safe, since we have a reference from open(). */
__module_get(THIS_MODULE);
- /* suppress uevents while reconfiguring the device */
- dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
-
/*
* If we don't hold exclusive handle for the device, upgrade to it
* here to avoid changing device under exclusive owner.
@@ -1067,6 +1064,9 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
}
}
+ /* suppress uevents while reconfiguring the device */
+ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 1);
+
disk_force_media_change(lo->lo_disk, DISK_EVENT_MEDIA_CHANGE);
set_disk_ro(lo->lo_disk, (lo->lo_flags & LO_FLAGS_READ_ONLY) != 0);
@@ -1109,17 +1109,17 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
if (partscan)
clear_bit(GD_SUPPRESS_PART_SCAN, &lo->lo_disk->state);
+ /* enable and uncork uevent now that we are done */
+ dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
+
loop_global_unlock(lo, is_loop);
if (partscan)
loop_reread_partitions(lo);
+
if (!(mode & FMODE_EXCL))
bd_abort_claiming(bdev, loop_configure);
- error = 0;
-done:
- /* enable and uncork uevent now that we are done */
- dev_set_uevent_suppress(disk_to_dev(lo->lo_disk), 0);
- return error;
+ return 0;
out_unlock:
loop_global_unlock(lo, is_loop);
@@ -1130,7 +1130,7 @@ static int loop_configure(struct loop_device *lo, fmode_t mode,
fput(file);
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
- goto done;
+ return error;
}
static void __loop_clr_fd(struct loop_device *lo, bool release)
--
2.39.2
