linux-kernel - Re: [f2fs-dev] [PATCH 4/4] f2fs: avoid wrong f2fs_bug_on when truncating inline

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Message-ID: <20150318175750.GB7461@jaegeuk-mac02>
Date:	Wed, 18 Mar 2015 10:57:50 -0700
From:	Jaegeuk Kim <jaegeuk@...nel.org>
To:	Chao Yu <chao2.yu@...sung.com>
Cc:	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-f2fs-devel@...ts.sourceforge.net
Subject: Re: [f2fs-dev] [PATCH 4/4] f2fs: avoid wrong f2fs_bug_on when
 truncating inline_data

Hi,

On Wed, Mar 18, 2015 at 09:12:00AM +0800, Chao Yu wrote:
> Hi Jaegeuk,
> 
> > -----Original Message-----
> > From: Jaegeuk Kim [mailto:jaegeuk@...nel.org]
> > Sent: Wednesday, March 18, 2015 12:58 AM
> > To: linux-kernel@...r.kernel.org; linux-fsdevel@...r.kernel.org;
> > linux-f2fs-devel@...ts.sourceforge.net
> > Cc: Jaegeuk Kim
> > Subject: [f2fs-dev] [PATCH 4/4] f2fs: avoid wrong f2fs_bug_on when truncating inline_data
> > 
> > This patch removes wrong f2fs_bug_on in truncate_inline_inode.
> > 
> > When there is no space, it can happen a corner case where i_isze is over
> > MAX_INLINE_SIZE while its inode is still inline_data.
> > 
> > The scenario is
> >  1. write small data into file #A.
> >  2. fill the whole partition to 100%.
> >  3. truncate 4096 on file #A.
> 
> If we truncate size over MAX_INLINE_DATA, we will convert inline data in
> f2fs_truncate rather than write_begin below. isn't it?

But, it fails to convert that due to -ENOSPC. :)

Thanks,

> 
> Thanks,
> 
> >  4. write data at 8192 offset.
> >   --> f2fs_write_begin
> >     -> -ENOSPC = f2fs_convert_inline_page
> >     -> f2fs_write_failed
> >       -> truncate_blocks
> >         -> truncate_inline_inode
> > 	  BUG_ON, since i_size is 4096.
> > 
> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
> > ---
> >  fs/f2fs/inline.c | 7 -------
> >  1 file changed, 7 deletions(-)
> > 
> > diff --git a/fs/f2fs/inline.c b/fs/f2fs/inline.c
> > index 153c5e7..d3e0599 100644
> > --- a/fs/f2fs/inline.c
> > +++ b/fs/f2fs/inline.c
> > @@ -54,13 +54,6 @@ bool truncate_inline_inode(struct page *ipage, u64 from)
> >  {
> >  	void *addr;
> > 
> > -	/*
> > -	 * we should never truncate inline data past max inline data size,
> > -	 * because we always convert inline inode to normal one before
> > -	 * truncating real data if new size is past max inline data size.
> > -	 */
> > -	f2fs_bug_on(F2FS_P_SB(ipage), from > MAX_INLINE_DATA);
> > -
> >  	if (from >= MAX_INLINE_DATA)
> >  		return false;
> > 
> > --
> > 2.1.1
> > 
> > 
> > ------------------------------------------------------------------------------
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