From: Jan Kara <jack@suse.cz>
To: Chengguang Xu <cgxu519@mykernel.net>
Cc: miklos@szeredi.hu, amir73il@gmail.com, jack@suse.cz,
linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC PATCH v2 5/8] ovl: mark overlayfs' inode dirty on shared writable mmap
Date: Mon, 2 Nov 2020 18:30:52 +0100 [thread overview]
Message-ID: <20201102173052.GF23988@quack2.suse.cz> (raw)
In-Reply-To: <20201025034117.4918-6-cgxu519@mykernel.net>
On Sun 25-10-20 11:41:14, Chengguang Xu wrote:
> Overlayfs cannot be notified when mmapped area gets dirty,
> so we need to proactively mark inode dirty in ->mmap operation.
>
> Signed-off-by: Chengguang Xu <cgxu519@mykernel.net>
> ---
> fs/overlayfs/file.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
> index efccb7c1f9bc..cd6fcdfd81a9 100644
> --- a/fs/overlayfs/file.c
> +++ b/fs/overlayfs/file.c
> @@ -486,6 +486,10 @@ static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
> /* Drop reference count from new vm_file value */
> fput(realfile);
> } else {
> + if (vma->vm_flags & (VM_SHARED|VM_MAYSHARE) &&
> + vma->vm_flags & (VM_WRITE|VM_MAYWRITE))
> + ovl_mark_inode_dirty(file_inode(file));
> +
But does this work reliably? I mean once writeback runs, your inode (as
well as upper inode) is cleaned. Then a page fault comes so file has dirty
pages again and would need flushing but overlayfs inode stays clean? Am I
missing something?
Honza
--
Jan Kara <jack@suse.com>
SUSE Labs, CR
next prev parent reply other threads:[~2020-11-02 17:30 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-25 3:41 [RFC PATCH v2 0/8] implement containerized syncfs for overlayfs Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 1/8] ovl: setup overlayfs' private bdi Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 2/8] ovl: implement ->writepages operation Chengguang Xu
2020-11-02 17:17 ` Jan Kara
2020-11-04 12:18 ` Chengguang Xu
2020-11-05 13:55 ` Jan Kara
2020-11-06 5:57 ` Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 3/8] ovl: implement overlayfs' ->evict_inode operation Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 4/8] ovl: mark overlayfs' inode dirty on modification Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 5/8] ovl: mark overlayfs' inode dirty on shared writable mmap Chengguang Xu
2020-11-02 17:30 ` Jan Kara [this message]
2020-11-04 11:54 ` Chengguang Xu
2020-11-05 14:03 ` Jan Kara
2020-11-05 14:21 ` Amir Goldstein
2020-11-05 15:54 ` Jan Kara
2020-11-06 2:41 ` Chengguang Xu
2020-11-06 8:50 ` Jan Kara
2020-11-06 9:47 ` Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 6/8] ovl: implement overlayfs' ->write_inode operation Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 7/8] ovl: cache dirty overlayfs' inode Chengguang Xu
2020-10-25 3:41 ` [RFC PATCH v2 8/8] ovl: implement containerized syncfs for overlayfs Chengguang Xu
2020-10-30 15:46 ` [RFC PATCH v2 0/8] " Miklos Szeredi
2020-10-31 12:22 ` Chengguang Xu
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