* [PATCH] f2fs: Fix deadlock in shutdown ioctl
@ 2018-05-10 13:20 Sahitya Tummala
2018-05-14 3:39 ` Chao Yu
0 siblings, 1 reply; 5+ messages in thread
From: Sahitya Tummala @ 2018-05-10 13:20 UTC (permalink / raw)
To: Jaegeuk Kim, Chao Yu, linux-f2fs-devel; +Cc: linux-kernel, Sahitya Tummala
f2fs_ioc_shutdown() ioctl gets stuck in the below path
when going down with full sync (F2FS_GOING_DOWN_FULLSYNC)
option.
__switch_to+0x90/0xc4
percpu_down_write+0x8c/0xc0
freeze_super+0xec/0x1e4
freeze_bdev+0xc4/0xcc
f2fs_ioctl+0xc0c/0x1ce0
f2fs_compat_ioctl+0x98/0x1f0
Fix this by not holding write access during this ioctl.
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
---
fs/f2fs/file.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index b926df7..2c2e61b 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -1835,10 +1835,6 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
if (get_user(in, (__u32 __user *)arg))
return -EFAULT;
- ret = mnt_want_write_file(filp);
- if (ret)
- return ret;
-
switch (in) {
case F2FS_GOING_DOWN_FULLSYNC:
sb = freeze_bdev(sb->s_bdev);
@@ -1878,7 +1874,6 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
f2fs_update_time(sbi, REQ_TIME);
out:
- mnt_drop_write_file(filp);
return ret;
}
--
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.
^ permalink raw reply related [flat|nested] 5+ messages in thread
* Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
2018-05-10 13:20 [PATCH] f2fs: Fix deadlock in shutdown ioctl Sahitya Tummala
@ 2018-05-14 3:39 ` Chao Yu
2018-05-15 7:57 ` Sahitya Tummala
0 siblings, 1 reply; 5+ messages in thread
From: Chao Yu @ 2018-05-14 3:39 UTC (permalink / raw)
To: Sahitya Tummala, Jaegeuk Kim, linux-f2fs-devel; +Cc: linux-kernel
On 2018/5/10 21:20, Sahitya Tummala wrote:
> f2fs_ioc_shutdown() ioctl gets stuck in the below path
> when going down with full sync (F2FS_GOING_DOWN_FULLSYNC)
> option.
>
> __switch_to+0x90/0xc4
> percpu_down_write+0x8c/0xc0
> freeze_super+0xec/0x1e4
> freeze_bdev+0xc4/0xcc
> f2fs_ioctl+0xc0c/0x1ce0
> f2fs_compat_ioctl+0x98/0x1f0
>
> Fix this by not holding write access during this ioctl.
I think we can just remove lock coverage for F2FS_GOING_DOWN_FULLSYNC path, for
other path, we need to keep as it is.
Thanks,
>
> Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
> ---
> fs/f2fs/file.c | 5 -----
> 1 file changed, 5 deletions(-)
>
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index b926df7..2c2e61b 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1835,10 +1835,6 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
> if (get_user(in, (__u32 __user *)arg))
> return -EFAULT;
>
> - ret = mnt_want_write_file(filp);
> - if (ret)
> - return ret;
> -
> switch (in) {
> case F2FS_GOING_DOWN_FULLSYNC:
> sb = freeze_bdev(sb->s_bdev);
> @@ -1878,7 +1874,6 @@ static int f2fs_ioc_shutdown(struct file *filp, unsigned long arg)
>
> f2fs_update_time(sbi, REQ_TIME);
> out:
> - mnt_drop_write_file(filp);
> return ret;
> }
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
2018-05-14 3:39 ` Chao Yu
@ 2018-05-15 7:57 ` Sahitya Tummala
2018-05-16 6:48 ` Chao Yu
0 siblings, 1 reply; 5+ messages in thread
From: Sahitya Tummala @ 2018-05-15 7:57 UTC (permalink / raw)
To: Chao Yu; +Cc: Jaegeuk Kim, linux-f2fs-devel, linux-kernel
On Mon, May 14, 2018 at 11:39:42AM +0800, Chao Yu wrote:
> On 2018/5/10 21:20, Sahitya Tummala wrote:
> > f2fs_ioc_shutdown() ioctl gets stuck in the below path
> > when going down with full sync (F2FS_GOING_DOWN_FULLSYNC)
> > option.
> >
> > __switch_to+0x90/0xc4
> > percpu_down_write+0x8c/0xc0
> > freeze_super+0xec/0x1e4
> > freeze_bdev+0xc4/0xcc
> > f2fs_ioctl+0xc0c/0x1ce0
> > f2fs_compat_ioctl+0x98/0x1f0
> >
> > Fix this by not holding write access during this ioctl.
>
> I think we can just remove lock coverage for F2FS_GOING_DOWN_FULLSYNC path, for
> other path, we need to keep as it is.
>
Thanks, I thought about it too but then I checked that XFS shutdown ioctl is
not taking any lock for this ioctl. Hence, I followed the same in F2FS.
Do you know why XFS is not taking any lock? Is it really needed in shutdown
ioctl?
--
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
2018-05-15 7:57 ` Sahitya Tummala
@ 2018-05-16 6:48 ` Chao Yu
2018-05-16 7:32 ` Sahitya Tummala
0 siblings, 1 reply; 5+ messages in thread
From: Chao Yu @ 2018-05-16 6:48 UTC (permalink / raw)
To: Sahitya Tummala; +Cc: Jaegeuk Kim, linux-f2fs-devel, linux-kernel
On 2018/5/15 15:57, Sahitya Tummala wrote:
> On Mon, May 14, 2018 at 11:39:42AM +0800, Chao Yu wrote:
>> On 2018/5/10 21:20, Sahitya Tummala wrote:
>>> f2fs_ioc_shutdown() ioctl gets stuck in the below path
>>> when going down with full sync (F2FS_GOING_DOWN_FULLSYNC)
>>> option.
>>>
>>> __switch_to+0x90/0xc4
>>> percpu_down_write+0x8c/0xc0
>>> freeze_super+0xec/0x1e4
>>> freeze_bdev+0xc4/0xcc
>>> f2fs_ioctl+0xc0c/0x1ce0
>>> f2fs_compat_ioctl+0x98/0x1f0
>>>
>>> Fix this by not holding write access during this ioctl.
>>
>> I think we can just remove lock coverage for F2FS_GOING_DOWN_FULLSYNC path, for
>> other path, we need to keep as it is.
>>
>
> Thanks, I thought about it too but then I checked that XFS shutdown ioctl is
> not taking any lock for this ioctl. Hence, I followed the same in F2FS.
> Do you know why XFS is not taking any lock?
I don't know. :(
> Is it really needed in shutdown ioctl?
IMO, yes, we should keep freeze and remount be aware of the shutdown operation.
Thanks,
>
> --
> Sent by a consultant of the Qualcomm Innovation Center, Inc.
> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
>
>
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
2018-05-16 6:48 ` Chao Yu
@ 2018-05-16 7:32 ` Sahitya Tummala
0 siblings, 0 replies; 5+ messages in thread
From: Sahitya Tummala @ 2018-05-16 7:32 UTC (permalink / raw)
To: Chao Yu; +Cc: Jaegeuk Kim, linux-f2fs-devel, linux-kernel
On Wed, May 16, 2018 at 02:48:42PM +0800, Chao Yu wrote:
> >
> > Thanks, I thought about it too but then I checked that XFS shutdown ioctl is
> > not taking any lock for this ioctl. Hence, I followed the same in F2FS.
> > Do you know why XFS is not taking any lock?
>
> I don't know. :(
No problem :)
>
> > Is it really needed in shutdown ioctl?
>
> IMO, yes, we should keep freeze and remount be aware of the shutdown operation.
Thanks for your inputs. I will send the updated patch set.
--
Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2018-05-16 7:32 UTC | newest]
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2018-05-10 13:20 [PATCH] f2fs: Fix deadlock in shutdown ioctl Sahitya Tummala
2018-05-14 3:39 ` Chao Yu
2018-05-15 7:57 ` Sahitya Tummala
2018-05-16 6:48 ` Chao Yu
2018-05-16 7:32 ` Sahitya Tummala
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