Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
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.
Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
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. > >
Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
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.
Re: [PATCH] f2fs: Fix deadlock in shutdown ioctl
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 > --- > 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; > } > >
[PATCH] f2fs: Fix deadlock in shutdown ioctl
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 --- 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.