Re: [PATCH v2] f2fs: Fix deadlock in shutdown ioctl

[Sahitya Tummala]

On Thu, May 17, 2018 at 06:08:26PM -0700, Jaegeuk Kim wrote:
> 
> if (in == F2FS_GOING_DOWN_FULLSYNC) {
>   sb = freeze_bdev();
>   if (IS_ERR(sb))
>   return PTR_ERR(sb);
>   if (unlikely(!sb))
>   return -EINVAL;
> }
> 
> ret = mnt_want_write_file();

It will be stuck/blocked here as freeze_bdev() now holds the write 
lock for all the cases including SB_FREEZE_WRITE. As freeze_bdev()
holds the write lock, I think f2fs_stop_checkpoint() should be safe
even without mnt_want_write_file().

I have posted v3 as per Chao's comments to exclude mnt_want_write_file()
for F2FS_GOING_DOWN_FULLSYNC case.
Please check and let me know if there are any further comments.

> ...
> switch() {
> case F2FS_GOING_DOWN_FULLSYNC:
>   f2fs_stop_checkpoint();
>   dhaw_bdev();
>   break;
> ...
> }
> 
> drop:
> ...
> 
> 
--
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 v2] f2fs: Fix deadlock in shutdown ioctl

[Sahitya Tummala]

On Thu, May 17, 2018 at 06:08:26PM -0700, Jaegeuk Kim wrote:
> 
> if (in == F2FS_GOING_DOWN_FULLSYNC) {
>   sb = freeze_bdev();
>   if (IS_ERR(sb))
>   return PTR_ERR(sb);
>   if (unlikely(!sb))
>   return -EINVAL;
> }
> 
> ret = mnt_want_write_file();

It will be stuck/blocked here as freeze_bdev() now holds the write 
lock for all the cases including SB_FREEZE_WRITE. As freeze_bdev()
holds the write lock, I think f2fs_stop_checkpoint() should be safe
even without mnt_want_write_file().

I have posted v3 as per Chao's comments to exclude mnt_want_write_file()
for F2FS_GOING_DOWN_FULLSYNC case.
Please check and let me know if there are any further comments.

> ...
> switch() {
> case F2FS_GOING_DOWN_FULLSYNC:
>   f2fs_stop_checkpoint();
>   dhaw_bdev();
>   break;
> ...
> }
> 
> drop:
> ...
> 
> 
--
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 v2] f2fs: Fix deadlock in shutdown ioctl

[Jaegeuk Kim]

On 05/17, Chao Yu wrote:
> On 2018/5/17 16:03, Sahitya Tummala wrote:
> > f2fs_ioc_shutdown() ioctl gets stuck in the below path
> > when issued with 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
> > 
> > Signed-off-by: Sahitya Tummala 
> > ---
> > v2:
> > remove lock coverage for only F2FS_GOING_DOWN_FULLSYNC case as suggested by 
> > Chao.
> > 
> >  fs/f2fs/file.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 6b94f19..5a132c9 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -1857,6 +1857,7 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> > unsigned long arg)
> 
> How about:
> 
> if (in != F2FS_GOING_DOWN_FULLSYNC)
>   mnt_want_write_file();
> 
> switch()
> {
>   handle command;
> }
> 
> if (in != F2FS_GOING_DOWN_FULLSYNC)
>   mnt_drop_write_file();
> 
> Thanks,

if (in == F2FS_GOING_DOWN_FULLSYNC) {
sb = freeze_bdev();
if (IS_ERR(sb))
return PTR_ERR(sb);
if (unlikely(!sb))
return -EINVAL;
}

ret = mnt_want_write_file();
...
switch() {
case F2FS_GOING_DOWN_FULLSYNC:
f2fs_stop_checkpoint();
dhaw_bdev();
break;
...
}

drop:
...


> 
> >  
> > switch (in) {
> > case F2FS_GOING_DOWN_FULLSYNC:
> > +   mnt_drop_write_file(filp);
> > sb = freeze_bdev(sb->s_bdev);
> > if (IS_ERR(sb)) {
> > ret = PTR_ERR(sb);
> > @@ -1894,7 +1895,8 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> > unsigned long arg)
> >  
> > f2fs_update_time(sbi, REQ_TIME);
> >  out:
> > -   mnt_drop_write_file(filp);
> > +   if (in != F2FS_GOING_DOWN_FULLSYNC)
> > +   mnt_drop_write_file(filp);
> > return ret;
> >  }
> >  
> > 

Re: [PATCH v2] f2fs: Fix deadlock in shutdown ioctl

[Jaegeuk Kim]

On 05/17, Chao Yu wrote:
> On 2018/5/17 16:03, Sahitya Tummala wrote:
> > f2fs_ioc_shutdown() ioctl gets stuck in the below path
> > when issued with 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
> > 
> > Signed-off-by: Sahitya Tummala 
> > ---
> > v2:
> > remove lock coverage for only F2FS_GOING_DOWN_FULLSYNC case as suggested by 
> > Chao.
> > 
> >  fs/f2fs/file.c | 4 +++-
> >  1 file changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 6b94f19..5a132c9 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -1857,6 +1857,7 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> > unsigned long arg)
> 
> How about:
> 
> if (in != F2FS_GOING_DOWN_FULLSYNC)
>   mnt_want_write_file();
> 
> switch()
> {
>   handle command;
> }
> 
> if (in != F2FS_GOING_DOWN_FULLSYNC)
>   mnt_drop_write_file();
> 
> Thanks,

if (in == F2FS_GOING_DOWN_FULLSYNC) {
sb = freeze_bdev();
if (IS_ERR(sb))
return PTR_ERR(sb);
if (unlikely(!sb))
return -EINVAL;
}

ret = mnt_want_write_file();
...
switch() {
case F2FS_GOING_DOWN_FULLSYNC:
f2fs_stop_checkpoint();
dhaw_bdev();
break;
...
}

drop:
...


> 
> >  
> > switch (in) {
> > case F2FS_GOING_DOWN_FULLSYNC:
> > +   mnt_drop_write_file(filp);
> > sb = freeze_bdev(sb->s_bdev);
> > if (IS_ERR(sb)) {
> > ret = PTR_ERR(sb);
> > @@ -1894,7 +1895,8 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> > unsigned long arg)
> >  
> > f2fs_update_time(sbi, REQ_TIME);
> >  out:
> > -   mnt_drop_write_file(filp);
> > +   if (in != F2FS_GOING_DOWN_FULLSYNC)
> > +   mnt_drop_write_file(filp);
> > return ret;
> >  }
> >  
> > 

Re: [PATCH v2] f2fs: Fix deadlock in shutdown ioctl

[Chao Yu]

On 2018/5/17 16:03, Sahitya Tummala wrote:
> f2fs_ioc_shutdown() ioctl gets stuck in the below path
> when issued with 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
> 
> Signed-off-by: Sahitya Tummala 
> ---
> v2:
> remove lock coverage for only F2FS_GOING_DOWN_FULLSYNC case as suggested by 
> Chao.
> 
>  fs/f2fs/file.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 6b94f19..5a132c9 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1857,6 +1857,7 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> unsigned long arg)

How about:

if (in != F2FS_GOING_DOWN_FULLSYNC)
mnt_want_write_file();

switch()
{
handle command;
}

if (in != F2FS_GOING_DOWN_FULLSYNC)
mnt_drop_write_file();

Thanks,

>  
>   switch (in) {
>   case F2FS_GOING_DOWN_FULLSYNC:
> + mnt_drop_write_file(filp);
>   sb = freeze_bdev(sb->s_bdev);
>   if (IS_ERR(sb)) {
>   ret = PTR_ERR(sb);
> @@ -1894,7 +1895,8 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> unsigned long arg)
>  
>   f2fs_update_time(sbi, REQ_TIME);
>  out:
> - mnt_drop_write_file(filp);
> + if (in != F2FS_GOING_DOWN_FULLSYNC)
> + mnt_drop_write_file(filp);
>   return ret;
>  }
>  
> 

Re: [PATCH v2] f2fs: Fix deadlock in shutdown ioctl

[Chao Yu]

On 2018/5/17 16:03, Sahitya Tummala wrote:
> f2fs_ioc_shutdown() ioctl gets stuck in the below path
> when issued with 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
> 
> Signed-off-by: Sahitya Tummala 
> ---
> v2:
> remove lock coverage for only F2FS_GOING_DOWN_FULLSYNC case as suggested by 
> Chao.
> 
>  fs/f2fs/file.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> index 6b94f19..5a132c9 100644
> --- a/fs/f2fs/file.c
> +++ b/fs/f2fs/file.c
> @@ -1857,6 +1857,7 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> unsigned long arg)

How about:

if (in != F2FS_GOING_DOWN_FULLSYNC)
mnt_want_write_file();

switch()
{
handle command;
}

if (in != F2FS_GOING_DOWN_FULLSYNC)
mnt_drop_write_file();

Thanks,

>  
>   switch (in) {
>   case F2FS_GOING_DOWN_FULLSYNC:
> + mnt_drop_write_file(filp);
>   sb = freeze_bdev(sb->s_bdev);
>   if (IS_ERR(sb)) {
>   ret = PTR_ERR(sb);
> @@ -1894,7 +1895,8 @@ static int f2fs_ioc_shutdown(struct file *filp, 
> unsigned long arg)
>  
>   f2fs_update_time(sbi, REQ_TIME);
>  out:
> - mnt_drop_write_file(filp);
> + if (in != F2FS_GOING_DOWN_FULLSYNC)
> + mnt_drop_write_file(filp);
>   return ret;
>  }
>  
>