Hey Jan,
On Tue, Oct 27, 2020 at 10:27 AM Jan Kara <jack@xxxxxxx> wrote:
>
> Commit afb585a97f81 "ext4: data=journal: write-protect pages on
> j_submit_inode_data_buffers()") added calls ext4_jbd2_inode_add_write()
> to track inode ranges whose mappings need to get write-protected during
> transaction commits. However the added calls use wrong start of a range
> (0 instead of page offset) and so write protection is not necessarily
> effective. Use correct range start to fix the problem.
>
> Fixes: afb585a97f81 ("ext4: data=journal: write-protect pages on j_submit_inode_data_buffers()")
> Signed-off-by: Jan Kara <jack@xxxxxxx>
> ---
> fs/ext4/inode.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> Mauricio, I think this could be the reason for occasional test failures you
> were still seeing. Can you try whether this patch fixes those for you? Thanks!
>
Thanks! Nice catch. Sure, I'll give it a try and follow up.
Just as FYI, I've been working on debugging and instrumentation to
identify the corner cases
where the page has not been write protected; but got a slower pace due
to other work items.
cheers,
Mauricio
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index 03c2253005f0..f4a599c6dcde 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -1918,7 +1918,7 @@ static int __ext4_journalled_writepage(struct page *page,
> }
> if (ret == 0)
> ret = err;
> - err = ext4_jbd2_inode_add_write(handle, inode, 0, len);
> + err = ext4_jbd2_inode_add_write(handle, inode, page_offset(page), len);
> if (ret == 0)
> ret = err;
> EXT4_I(inode)->i_datasync_tid = handle->h_transaction->t_tid;
> @@ -6157,7 +6157,8 @@ vm_fault_t ext4_page_mkwrite(struct vm_fault *vmf)
> if (ext4_walk_page_buffers(handle, page_buffers(page),
> 0, len, NULL, write_end_fn))
> goto out_error;
> - if (ext4_jbd2_inode_add_write(handle, inode, 0, len))
> + if (ext4_jbd2_inode_add_write(handle, inode,
> + page_offset(page), len))
> goto out_error;
> ext4_set_inode_state(inode, EXT4_STATE_JDATA);
> } else {
> --
> 2.16.4
>
--
Mauricio Faria de Oliveira
