Re: [f2fs-dev] [PATCH] f2fs: fix to access i_size w/ i_size_read()

Yongpeng Yang
2025-10-29T08:09:49Z

On 10/29/25 14:31, Chao Yu via Linux-f2fs-devel wrote:
> It recommends to use i_size_{read,write}() to access and update i_size,
> otherwise, we may get wrong tearing value due to high 32-bits value
> and low 32-bits value of i_size field are not updated atomically in
> 32-bits archicture machine.
>
> Signed-off-by: Chao Yu <chao@kernel.org>
> ---
> include/trace/events/f2fs.h | 8 ++++----
> 1 file changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/include/trace/events/f2fs.h b/include/trace/events/f2fs.h
> index edbbd869078f..e1fae78d64a5 100644
> --- a/include/trace/events/f2fs.h
> +++ b/include/trace/events/f2fs.h
> @@ -204,7 +204,7 @@ DECLARE_EVENT_CLASS(f2fs__inode,
> __entry->pino = F2FS_I(inode)->i_pino;
> __entry->mode = inode->i_mode;
> __entry->nlink = inode->i_nlink;
> - __entry->size = inode->i_size;
> + __entry->size = i_size_read(inode);
> __entry->blocks = inode->i_blocks;
> __entry->advise = F2FS_I(inode)->i_advise;
> ),
> @@ -353,7 +353,7 @@ TRACE_EVENT(f2fs_unlink_enter,
> TP_fast_assign(
> __entry->dev = dir->i_sb->s_dev;
> __entry->ino = dir->i_ino;
> - __entry->size = dir->i_size;
> + __entry->size = i_size_read(dir);
> __entry->blocks = dir->i_blocks;
> __assign_str(name);
> ),
> @@ -433,7 +433,7 @@ DECLARE_EVENT_CLASS(f2fs__truncate_op,
> TP_fast_assign(
> __entry->dev = inode->i_sb->s_dev;
> __entry->ino = inode->i_ino;
> - __entry->size = inode->i_size;
> + __entry->size = i_size_read(inode);
> __entry->blocks = inode->i_blocks;
> __entry->from = from;
> ),
> @@ -1006,7 +1006,7 @@ TRACE_EVENT(f2fs_fallocate,
> __entry->mode = mode;
> __entry->offset = offset;
> __entry->len = len;
> - __entry->size = inode->i_size;
> + __entry->size = i_size_read(inode);
> __entry->blocks = inode->i_blocks;
> __entry->ret = ret;
> ),

inode->i_size usage in fs/f2fs/ also needs to be updated. For example in
f2fs_need_verity(), which may not protected by inode_lock.

Yongpeng,