Re: [PATCH] f2fs: compress: fix to cover f2fs_disable_compressed_file() w/ i_sem

[Chao Yu]

On 2024/1/17 2:29, Jaegeuk Kim wrote:
> On 01/11, Chao Yu wrote:
> > - f2fs_disable_compressed_file
> >    - check inode_has_data
> > 					- f2fs_file_mmap
> > 					- mkwrite
> > 					 - f2fs_get_block_locked
> > 					 : update metadata in compressed
> > 					   inode's disk layout
> >    - fi->i_flags &= ~F2FS_COMPR_FL
> >    - clear_inode_flag(inode, FI_COMPRESSED_FILE);
> >
> > we should use i_sem lock to prevent above race case.
> >
> > Meanwhile, this patch adds i_size check to restrict compress inode
> > conversion condition.
>
> Sorry, what was the reason to check i_size?

Oh, I don't see any race condition, let's remove it in v2.

Thanks,

> > Fixes: 4c8ff7095bef ("f2fs: support data compression")
> > Signed-off-by: Chao Yu <chao@xxxxxxxxxx>
> > ---
> >   fs/f2fs/f2fs.h | 18 ++++++++++++++++--
> >   fs/f2fs/file.c |  5 ++---
> >   2 files changed, 18 insertions(+), 5 deletions(-)
> >
> > diff --git a/fs/f2fs/f2fs.h b/fs/f2fs/f2fs.h
> > index 74729db0b381..e2e0ca45f881 100644
> > --- a/fs/f2fs/f2fs.h
> > +++ b/fs/f2fs/f2fs.h
> > @@ -4406,19 +4406,33 @@ 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))
> > +	f2fs_down_write(&F2FS_I(inode)->i_sem);
> > +
> > +	if (!f2fs_compressed_file(inode)) {
> > +		f2fs_up_write(&F2FS_I(inode)->i_sem);
> >   		return true;
> > -	if (S_ISREG(inode->i_mode) && F2FS_HAS_BLOCKS(inode))
> > +	}
> > +	if (f2fs_is_mmap_file(inode) || inode_has_data(inode)) {
> > +		f2fs_up_write(&F2FS_I(inode)->i_sem);
> >   		return false;
> > +	}
> >   
> >   	fi->i_flags &= ~F2FS_COMPR_FL;
> >   	stat_dec_compr_inode(inode);
> >   	clear_inode_flag(inode, FI_COMPRESSED_FILE);
> >   	f2fs_mark_inode_dirty_sync(inode, true);
> > +
> > +	f2fs_up_write(&F2FS_I(inode)->i_sem);
> >   	return true;
> >   }
> >   
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
> > index 0e4c871d6aed..5e5df234eb92 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -1926,8 +1926,7 @@ 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;
> >   			}
> > @@ -4011,7 +4010,7 @@ 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