[PATCH] f2fs: move put_gc_inode into gc_mutex

[PATCH] f2fs: move put_gc_inode into gc_mutex

[Changman Lee]

There in no any lock to protect gc_inode list so let's move into
gc_mutex, otherwise it might be lost links of list.

Signed-off-by: Changman Lee <cm224.lee@samsung.com>
---
 fs/f2fs/gc.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
index 657683c9..99e1720 100644
--- a/fs/f2fs/gc.c
+++ b/fs/f2fs/gc.c
@@ -733,9 +733,9 @@ gc_more:
 	if (gc_type == FG_GC)
 		write_checkpoint(sbi, &cpc);
 stop:
-	mutex_unlock(&sbi->gc_mutex);
-
 	put_gc_inode(&ilist);
+
+	mutex_unlock(&sbi->gc_mutex);
 	return ret;
 }
 
-- 
1.9.1

Re: [f2fs-dev] [PATCH] f2fs: move put_gc_inode into gc_mutex

[Jaegeuk Kim]

Hi Changman,

On Thu, Nov 27, 2014 at 06:42:54PM +0900, Changman Lee wrote:
> There in no any lock to protect gc_inode list so let's move into
> gc_mutex, otherwise it might be lost links of list.

Could you explain why the links can be lost?
Cause the ilist is a local variable.

IIRC, the reason why put_gc_inode is called outside of gc_mutex is to avoid
deadlock between f2fs_evict_inode and gc operations.
I'm not sure it still has a problem, but it is unclear that we have to move
put_gc_inode inside gc_mutex.

Are you facing with any bug on this?

Thanks,

> 
> Signed-off-by: Changman Lee <cm224.lee@samsung.com>
> ---
>  fs/f2fs/gc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> index 657683c9..99e1720 100644
> --- a/fs/f2fs/gc.c
> +++ b/fs/f2fs/gc.c
> @@ -733,9 +733,9 @@ gc_more:
>  	if (gc_type == FG_GC)
>  		write_checkpoint(sbi, &cpc);
>  stop:
> -	mutex_unlock(&sbi->gc_mutex);
> -
>  	put_gc_inode(&ilist);
> +
> +	mutex_unlock(&sbi->gc_mutex);
>  	return ret;
>  }
>  
> -- 
> 1.9.1
> 
> 
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Re: [f2fs-dev] [PATCH] f2fs: move put_gc_inode into gc_mutex

[Changman Lee]

On Thu, Nov 27, 2014 at 07:55:14PM -0800, Jaegeuk Kim wrote:
> Hi Changman,
> 
> On Thu, Nov 27, 2014 at 06:42:54PM +0900, Changman Lee wrote:
> > There in no any lock to protect gc_inode list so let's move into
> > gc_mutex, otherwise it might be lost links of list.
> 
> Could you explain why the links can be lost?
> Cause the ilist is a local variable.

Hi Jaegeuk,

Oh, I missed ilist is a local variable.
Sorry, ignore this patch.

Thanks,

> 
> IIRC, the reason why put_gc_inode is called outside of gc_mutex is to avoid
> deadlock between f2fs_evict_inode and gc operations.
> I'm not sure it still has a problem, but it is unclear that we have to move
> put_gc_inode inside gc_mutex.
> 
> Are you facing with any bug on this?
> 
> Thanks,
> 
> > 
> > Signed-off-by: Changman Lee <cm224.lee@samsung.com>
> > ---
> >  fs/f2fs/gc.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
> > index 657683c9..99e1720 100644
> > --- a/fs/f2fs/gc.c
> > +++ b/fs/f2fs/gc.c
> > @@ -733,9 +733,9 @@ gc_more:
> >  	if (gc_type == FG_GC)
> >  		write_checkpoint(sbi, &cpc);
> >  stop:
> > -	mutex_unlock(&sbi->gc_mutex);
> > -
> >  	put_gc_inode(&ilist);
> > +
> > +	mutex_unlock(&sbi->gc_mutex);
> >  	return ret;
> >  }
> >  
> > -- 
> > 1.9.1
> > 
> > 
> > ------------------------------------------------------------------------------
> > Download BIRT iHub F-Type - The Free Enterprise-Grade BIRT Server
> > from Actuate! Instantly Supercharge Your Business Reports and Dashboards
> > with Interactivity, Sharing, Native Excel Exports, App Integration & more
> > Get technology previously reserved for billion-dollar corporations, FREE
> > http://pubads.g.doubleclick.net/gampad/clk?id=157005751&iu=/4140/ostg.clktrk
> > _______________________________________________
> > Linux-f2fs-devel mailing list
> > Linux-f2fs-devel@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel