Re: [RFC][PATCH 2/14] Add a new mount flag (MNT_UNION) for unionmount

[Jan Engelhardt]

On May 14 2007 15:09, Bharata B Rao wrote:
>
>Introduce MNT_UNION, MS_UNION and FS_WHT flags. There are the necessary flags
>for doing
>
>    mount /dev/hda3 /mnt -o union
>
>You need additional patches for util-linux for that to work.
>
>Signed-off-by: Jan Blunck <j.blunck@xxxxxxxxxxxxx>
>Signed-off-by: Bharata B Rao <bharata@xxxxxxxxxxxxxxxxxx>
>---
> 
>+	/* Unions couldn't be writable if the filesystem
>+	 * doesn't know about whiteouts */
>+	err = -ENOTSUPP;
>+	if ((mnt_flags & MNT_UNION) &&
>+	    !(newmnt->mnt_sb->s_flags & MS_RDONLY) &&
>+	    !(newmnt->mnt_sb->s_type->fs_flags & FS_WHT))
>+		goto unlock;
>+

Maybe I am too biased towards unionfs/aufs, but if I have an {rw,rw} union
with whiteouts disabled (delete=all in unionfs speak), then FS_WHT
does not need to be supported. Your patches do not seem to do
delete=all semantics, do they?

	Jan
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