Re: [PATCH 5/6] f2fs: fix to restrict condition of compress inode conversion

[Chao Yu]

On 2023/12/12 6:11, Jaegeuk Kim wrote:
> On 12/10, Chao Yu wrote:
> > This patch adds i_size check during compress inode conversion in order
> > to avoid .page_mkwrite races w/ conversion.
>
> Which race condition do you see?

Something like:

- f2fs_setflags_common
 - check S_ISREG && F2FS_HAS_BLOCKS
					- mkwrite
					 - f2fs_get_block_locked
					  : update metadata in old inode's disk layout
 - set_compress_context

Thanks,

> > Fixes: 4c8ff7095bef ("f2fs: support data compression")
> > Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
> > ---
> >   fs/f2fs/f2fs.h | 8 +++++++-
> >   fs/f2fs/file.c | 5 ++---
> >   2 files changed, 9 insertions(+), 4 deletions(-)
> >
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 65294e3b0bef..c9b8a1953913 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -4397,13 +4397,19 @@ static inline int set_compress_context(struct inode *inode)
> >   #endif
> >   }
> >   
> > +static inline bool inode_has_data(struct inode *inode)
> > +{
> > +	return (S_ISREG(inode->i_mode) &&
> > +		(F2FS_HAS_BLOCKS(inode) || i_size_read(inode)));
> > +}
> > +
> >   static inline bool f2fs_disable_compressed_file(struct inode *inode)
> >   {
> >   	struct f2fs_inode_info *fi = F2FS_I(inode);
> >   
> >   	if (!f2fs_compressed_file(inode))
> >   		return true;
> > -	if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
> > +	if (inode_has_data(inode))
> >   		return false;
> >   
> >   	fi->i_flags &= ~F2FS_COMPR_FL;
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 1a3c29a9a6a0..8af4b29c3e1a 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -1922,8 +1922,7 @@ static int f2fs_setflags_common(struct inode *inode, u32 iflags, u32 mask)
> >   
> >   			f2fs_down_write(&F2FS_I(inode)->i_sem);
> >   			if (!f2fs_may_compress(inode) ||
> > -					(S_ISREG(inode->i_mode) &&
> > -					F2FS_HAS_BLOCKS(inode))) {
> > +					inode_has_data(inode)) {
> >   				f2fs_up_write(&F2FS_I(inode)->i_sem);
> >   				return -EINVAL;
> >   			}
> > @@ -3996,7 +3995,7 @@ static int f2fs_ioc_set_compress_option(struct file *filp, unsigned long arg)
> >   		goto out;
> >   	}
> >   
> > -	if (F2FS_HAS_BLOCKS(inode)) {
> > +	if (inode_has_data(inode)) {
> >   		ret = -EFBIG;
> >   		goto out;
> >   	}
> > --
> > 2.40.1