This patch set fix two issues introduced by prior commit.
[PATCH v2 1/2] loop: do not print warn message if partition scan is successful
[PATCH v2 1/2] fixes d57f3374ba48 ("loop: Move special partition reread
handling in loop_clr_fd()") to not always print warn message even when
partition scan is successful.
[PATCH v2 2/2] loop: set GENHD_FL_NO_PART_SCAN after blkdev_reread_part()
[PATCH v2 2/2] fixes 0da03cab87e6 ("loop: Fix deadlock when calling
blkdev_reread_part()") to not set GENHD_FL_NO_PART_SCAN before partition
scan when detaching loop device from the file.
Changed since v1:
* move the setting of lo->lo_state to Lo_unbound after partscan has finished as well
(suggested by Jan Kara)
Dongli Zhang
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 <[email protected]>
---
Changed since v1:
* move the setting of lo->lo_state to Lo_unbound after partscan has finished as well
(suggested by Jan Kara)
drivers/block/loop.c | 26 ++++++++++++++++++++++----
1 file changed, 22 insertions(+), 4 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index 7908673..a13f5dc 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1034,6 +1034,16 @@ 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;
+ lo->lo_state = Lo_unbound;
+ mutex_unlock(&loop_ctl_mutex);
+}
+
static int __loop_clr_fd(struct loop_device *lo, bool release)
{
struct file *filp = NULL;
@@ -1089,16 +1099,12 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
kobject_uevent(&disk_to_dev(bdev->bd_disk)->kobj, KOBJ_CHANGE);
}
mapping_set_gfp_mask(filp->f_mapping, gfp);
- lo->lo_state = Lo_unbound;
/* This is safe: open() is still holding a reference. */
module_put(THIS_MODULE);
blk_mq_unfreeze_queue(lo->lo_queue);
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 +1127,18 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
/* Device is gone, no point in returning error */
err = 0;
}
+
+ /*
+ * lo->lo_state is set to Lo_unbound inside loop_disable_partscan()
+ * here after above partscan has finished.
+ *
+ * There cannot be anybody else entering __loop_clr_fd() as
+ * lo->lo_backing_file is already cleared and Lo_rundown state
+ * protects us from all the other places trying to change the 'lo'
+ * device.
+ */
+ 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
Do not print warn message when the partition scan returns 0.
Fixes: d57f3374ba48 ("loop: Move special partition reread handling in loop_clr_fd()")
Signed-off-by: Dongli Zhang <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
---
drivers/block/loop.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/block/loop.c b/drivers/block/loop.c
index cf55389..7908673 100644
--- a/drivers/block/loop.c
+++ b/drivers/block/loop.c
@@ -1115,8 +1115,9 @@ static int __loop_clr_fd(struct loop_device *lo, bool release)
err = __blkdev_reread_part(bdev);
else
err = blkdev_reread_part(bdev);
- pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
- __func__, lo_number, err);
+ if (err)
+ pr_warn("%s: partition scan of loop%d failed (rc=%d)\n",
+ __func__, lo_number, err);
/* Device is gone, no point in returning error */
err = 0;
}
--
2.7.4
On Thu 21-02-19 23:33:43, Dongli Zhang wrote:
> 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 <[email protected]>
> ---
> Changed since v1:
> * move the setting of lo->lo_state to Lo_unbound after partscan has finished as well
> (suggested by Jan Kara)
>
> drivers/block/loop.c | 26 ++++++++++++++++++++++----
> 1 file changed, 22 insertions(+), 4 deletions(-)
Thanks the patch looks good! Just one nit below:
> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
> index 7908673..a13f5dc 100644
> --- a/drivers/block/loop.c
> +++ b/drivers/block/loop.c
> @@ -1034,6 +1034,16 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
> return err;
> }
>
> +static void loop_disable_partscan(struct loop_device *lo)
> +{
I don't think there's any benefit in having this small function with a single
caller and furthermore with the subtle sideeffect that it changes lo_state.
So I'd just put the code inline in __loop_clr_fd(). With that you can add:
Reviewed-by: Jan Kara <[email protected]>
Honza
--
Jan Kara <[email protected]>
SUSE Labs, CR
On 02/22/2019 07:47 PM, Jan Kara wrote:
> On Thu 21-02-19 23:33:43, Dongli Zhang wrote:
>> 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 <[email protected]>
>> ---
>> Changed since v1:
>> * move the setting of lo->lo_state to Lo_unbound after partscan has finished as well
>> (suggested by Jan Kara)
>>
>> drivers/block/loop.c | 26 ++++++++++++++++++++++----
>> 1 file changed, 22 insertions(+), 4 deletions(-)
>
> Thanks the patch looks good! Just one nit below:
>
>> diff --git a/drivers/block/loop.c b/drivers/block/loop.c
>> index 7908673..a13f5dc 100644
>> --- a/drivers/block/loop.c
>> +++ b/drivers/block/loop.c
>> @@ -1034,6 +1034,16 @@ loop_init_xfer(struct loop_device *lo, struct loop_func_table *xfer,
>> return err;
>> }
>>
>> +static void loop_disable_partscan(struct loop_device *lo)
>> +{
>
> I don't think there's any benefit in having this small function with a single
> caller and furthermore with the subtle sideeffect that it changes lo_state.
> So I'd just put the code inline in __loop_clr_fd(). With that you can add:
>
> Reviewed-by: Jan Kara <[email protected]>
Thank you very much!
I will send out v3 with the Reviewed-by and put the code inline in __loop_clr_fd().
Dongli Zhang
>
> Honza
>