Commit 0da03cab87e6
("loop: Fix deadlock when calling blkdev_reread_part()") moves
blkdev_reread_part() out of the loop_ctl_mutex. However,
GENHD_FL_NO_PART_SCAN is set before __blkdev_reread_part(). As a result,
__blkdev_reread_part() will fail the check of GENHD_FL_NO_PART_SCAN and
will not rescan the loop device to delete all partitions.
Below are steps to reproduce the issue:
step1 # dd if=/dev/zero of=tmp.raw bs=1M count=100
step2 # losetup -P /dev/loop0 tmp.raw
step3 # parted /dev/loop0 mklabel gpt
step4 # parted -a none -s /dev/loop0 mkpart primary 64s 1
step5 # losetup -d /dev/loop0
Step5 will not be able to delete /dev/loop0p1 (introduced by step4) and
there is below kernel warning message:
[ 464.414043] __loop_clr_fd: partition scan of loop0 failed (rc=-22)
This patch sets GENHD_FL_NO_PART_SCAN after blkdev_reread_part().
Fixes: 0da03cab87e6 ("loop: Fix deadlock when calling blkdev_reread_part()")
Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
drivers/block/loop.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 7908673..736e55b 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1034,6 +1034,15 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
return err;
}
+static void loop_disable_partscan(struct loop_device *lo)
+{
+ mutex_lock(&loop_ctl_mutex);
+ lo->lo_flags = 0;
+ if (!part_shift)
+ lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
+ mutex_unlock(&loop_ctl_mutex);
+}
+
static int __loop_clr_fd(struct loop_device *lo, bool release)
{
struct file *filp = NULL;
@@ -1096,9 +1105,6 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
partscan = lo->lo_flags & LO_FLAGS_PARTSCAN && bdev;
lo_number = lo->lo_number;
- lo->lo_flags = 0;
- if (!part_shift)
- lo->lo_disk->flags |= GENHD_FL_NO_PART_SCAN;
loop_unprepare_queue(lo);
out_unlock:
mutex_unlock(&loop_ctl_mutex);
@@ -1121,6 +1127,9 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
/* Device is gone, no point in returning error */
err = 0;
}
+
+ loop_disable_partscan(lo);
+
/*
* Need not hold loop_ctl_mutex to fput backing file.
* Calling fput holding loop_ctl_mutex triggers a circular
--
2.7.4
