On Mon, Jun 20, 2016 at 4:51 AM, <zhangaihua1@xxxxxxxxxx> wrote:
> From: Aihua Zhang <zhangaihua1@xxxxxxxxxx>
>
> I wrote a testcase to truncate a bin file while it is running at overlayfs.
> the result as below:
>
> Bus error (core dumped)
Thanks for the report.
Please tell us more information about how to trigger the bug:
- how did you set up the overlay filesystem?
- which test case from which test suite was this?
> I think it's not appropriate for filesystem, and fixed it by this patch.
> after the patch, result as below:
>
> status:-1
> errno:26
> ETXTBSY:26
> PASS
>
> This is because the inode is not correct ,it should point to overlayfs rather
> than the upper filesystem.
Changeing denty_write_access() without a similar change in
allow_write_access() is sure to buggy.
But even with that fixed, it's not clear to me why exactly this change
is needed. More thought needs to be going into this.
Thanks,
Miklos
>
> Signed-off-by: Aihua Zhang <zhangaihua1@xxxxxxxxxx>
> ---
> include/linux/fs.h | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index dd28814..54fdbf9 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2589,7 +2589,7 @@ static inline int get_write_access(struct inode *inode)
> }
> static inline int deny_write_access(struct file *file)
> {
> - struct inode *inode = file_inode(file);
> + struct inode *inode = d_inode(file->f_path.dentry);
> return atomic_dec_unless_positive(&inode->i_writecount) ? 0 : -ETXTBSY;
> }
> static inline void put_write_access(struct inode * inode)
> --
> 1.7.1
>
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