回复:[RFC PATCH v3 06/10] ovl: mark overlayfs' inode dirty on shared mmap

From: Chengguang Xu <cgxu519@mykernel.net>
To: "Chengguang Xu" <cgxu519@mykernel.net>
Cc: "miklos" <miklos@szeredi.hu>, "jack" <jack@suse.cz>,
	"amir73il" <amir73il@gmail.com>,
	"linux-unionfs" <linux-unionfs@vger.kernel.org>,
	"linux-fsdevel" <linux-fsdevel@vger.kernel.org>
Subject: 回复:[RFC PATCH v3 06/10] ovl: mark overlayfs' inode dirty on shared mmap
Date: Wed, 11 Nov 2020 21:05:27 +0800	[thread overview]
Message-ID: <175b769393e.da9339695127.2777354745619336639@mykernel.net> (raw)
In-Reply-To: <20201108140307.1385745-7-cgxu519@mykernel.net>

 ---- 在 星期日, 2020-11-08 22:03:03 Chengguang Xu <cgxu519@mykernel.net> 撰写 ----
 > 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 | 2 ++
 >  1 file changed, 2 insertions(+)
 > 
 > diff --git a/fs/overlayfs/file.c b/fs/overlayfs/file.c
 > index efccb7c1f9bc..662252047fff 100644
 > --- a/fs/overlayfs/file.c
 > +++ b/fs/overlayfs/file.c
 > @@ -486,6 +486,8 @@ 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))

Maybe it's better to mark dirty only having upper inode.

 > +            ovl_mark_inode_dirty(file_inode(file));
 >          /* Drop reference count from previous vm_file value */
 >          fput(file);
 >      }
 > -- 
 > 2.26.2
 > 
 > 
 > 