diff options
| author | Daan De Meyer <daan@amutable.com> | 2026-07-15 21:39:57 +0200 |
|---|---|---|
| committer | Jens Axboe <axboe@kernel.dk> | 2026-07-15 16:31:14 -0600 |
| commit | c4f4c0fc551cbcdccbbbc2d874d7d6440c7b4983 (patch) | |
| tree | 86802f749d75c3d07492996796e4cd3289ced323 /drivers | |
| parent | 691b052139c94ee6640ac39e0b764dd3867897c0 (diff) | |
loop: remove manually added partitions on detach
Commit 267ec4d7223a ("loop: fix partition scan race between udev and
loop_reread_partitions()") stopped disk_force_media_change() from
setting GD_NEED_PART_SCAN because loop devices with LO_FLAGS_PARTSCAN
rescan partitions explicitly. However, partitions can also be added
manually with BLKPG while LO_FLAGS_PARTSCAN is clear.
When such a loop device is detached, __loop_clr_fd() skips
bdev_disk_changed(). Without GD_NEED_PART_SCAN, reopening the unbound
device no longer performs the previous lazy cleanup, leaving dead
partition devices behind. A subsequent LOOP_CONFIGURE can then fail its
partition scan with -EBUSY, as seen in blktests loop/009 after loop/008.
Call bdev_disk_changed() unconditionally during __loop_clr_fd(). The
disk capacity is already zero and the release path holds open_mutex, so
this drops all partitions without rescanning the detached backing file.
The new blktests loop/013 case covers this sequence by adding a partition
with BLKPG without LO_FLAGS_PARTSCAN, detaching the loop device, and
checking that the partition is gone when the device is reopened.
Fixes: 267ec4d7223a ("loop: fix partition scan race between udev and loop_reread_partitions()")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202607150754.b660f5b9-lkp@intel.com
Signed-off-by: Daan De Meyer <daan@amutable.com>
Link: https://patch.msgid.link/20260715-b4-loop-partition-cleanup-v1-1-b9f59910cd1e@amutable.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/block/loop.c | 32 |
1 files changed, 14 insertions, 18 deletions
diff --git a/drivers/block/loop.c b/drivers/block/loop.c index 310de0463beb..1faecef33009 100644 --- a/drivers/block/loop.c +++ b/drivers/block/loop.c @@ -1113,6 +1113,7 @@ static void __loop_clr_fd(struct loop_device *lo) struct queue_limits lim; struct file *filp; gfp_t gfp = lo->old_gfp_mask; + int err; spin_lock_irq(&lo->lo_lock); filp = lo->lo_backing_file; @@ -1146,26 +1147,21 @@ static void __loop_clr_fd(struct loop_device *lo) disk_force_media_change(lo->lo_disk); - if (lo->lo_flags & LO_FLAGS_PARTSCAN) { - int err; - - /* - * open_mutex has been held already in release path, so don't - * acquire it if this function is called in such case. - * - * If the reread partition isn't from release path, lo_refcnt - * must be at least one and it can only become zero when the - * current holder is released. - */ - err = bdev_disk_changed(lo->lo_disk, false); - if (err) - pr_warn("%s: partition scan of loop%d failed (rc=%d)\n", - __func__, lo->lo_number, err); - /* Device is gone, no point in returning error */ - } + /* + * Remove all partitions, including partitions added manually with + * BLKPG, which may exist even if LO_FLAGS_PARTSCAN is not set. + * + * open_mutex has been held already in release path, so don't acquire + * it here. + */ + err = bdev_disk_changed(lo->lo_disk, false); + if (err) + pr_warn("%s: partition scan of loop%d failed (rc=%d)\n", + __func__, lo->lo_number, err); + /* Device is gone, no point in returning error */ /* - * lo->lo_state is set to Lo_unbound here after above partscan has + * lo->lo_state is set to Lo_unbound here after removing partitions has * finished. There cannot be anybody else entering __loop_clr_fd() as * Lo_rundown state protects us from all the other places trying to * change the 'lo' device. |