[f2fs-dev] 答复: [PATCH] f2fs: Fix data consistency in f2fs_move_file_range()

[zhangqilong via Linux-f2fs-devel <linux-f2fs-devel@lists.sourceforge.net>]

> On 2022/10/18 10:45, Zhang Qilong wrote:
> > In the following case:
> > process 1			process 2
> >   ->open A
> >    ->mmap
> >     ->read # the first time
> >     				 ->ioctl w/h F2FS_IOC_MOVE_RANGE
> > 				        	# (range A->B)
> >     ->read # the second time
> 
> How about checking B as well? Previous mapped data can still be accessed
> after F2FS_IOC_MOVE_RANGE?
> 

Hi

I have checked B as well. Previous mapped data can't be accessed after
F2FS_IOC_MOVE_RANGE.

In addition, this patch could be applied to mainline if possible? 

Thanks

> Thanks,
> 
> >
> > We will read old data at the second time. The root cause is that user
> > still can see the previous source data after being moved. We fix it by
> > adding truncating after __exchange_data_block.
> >
> > Fixes: 4dd6f977fc77 ("f2fs: support an ioctl to move a range of data
> > blocks")
> > Signed-off-by: Zhang Qilong <zhangqilong3@huawei.com>
> > ---
> > v2:
> > - moving truncating to the range of f2fs_lock_op()
> >
> > v3:
> > - modify the title and commit message
> > ---
> >   fs/f2fs/file.c | 3 +++
> >   1 file changed, 3 insertions(+)
> >
> > diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index
> > 82cda1258227..e9dfa41baf9e 100644
> > --- a/fs/f2fs/file.c
> > +++ b/fs/f2fs/file.c
> > @@ -2824,6 +2824,7 @@ static int f2fs_move_file_range(struct file *file_in,
> loff_t pos_in,
> >   			goto out_src;
> >   	}
> >
> > +	filemap_invalidate_lock(src->i_mapping);
> >   	f2fs_lock_op(sbi);
> >   	ret = __exchange_data_block(src, dst, pos_in >> F2FS_BLKSIZE_BITS,
> >   				pos_out >> F2FS_BLKSIZE_BITS,
> > @@ -2835,7 +2836,9 @@ static int f2fs_move_file_range(struct file *file_in,
> loff_t pos_in,
> >   		else if (dst_osize != dst->i_size)
> >   			f2fs_i_size_write(dst, dst_osize);
> >   	}
> > +	truncate_pagecache_range(src, pos_in, pos_in + len - 1);
> >   	f2fs_unlock_op(sbi);
> > +	filemap_invalidate_unlock(src->i_mapping);
> >
> >   	if (src != dst)
> >   		f2fs_up_write(&F2FS_I(dst)->i_gc_rwsem[WRITE]);

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