Re: [PATCH 4/67] aufs configuration

From: Jan Engelhardt
Date: Fri May 16 2008 - 11:28:31 EST

On Friday 2008-05-16 16:32, hooanon05@xxxxxxxxxxx wrote:
>+if AUFS
>+config AUFS_FAKE_DM
>+ bool
>+ depends on AUFS
>+ default n

When you have "if AUFS" you do not need all the "depends on AUFS".

>+config AUFS_ROBR
>+ bool "Aufs as an readonly branch of another aufs"
>+ depends on AUFS
>+ default n
>+ help
>+ If you want make your aufs to be a part of another aufs, then
>+ enable this option. In other words, you can specify your aufs
>+ path in 'br:' mount option for another aufs, but cannot
>+ specify 'rw' as the branch permission.
>+ It will damage the performance.
>+ See detail in aufs.5.

IIRC, unionfs did not need such an option, so why does AUFS?

>+config AUFS_DLGT
>+ bool "Delegate the internal branch access the kernel thread"
>+ depends on AUFS
>+ default n

I do not think you need "default n" either as that should be the
implicit default.

>+ bool
>+ depends on AUFS
>+ default y

This should just go away if it is always selected anyway.

>+config AUFS_BR_NFS
>+ bool
>+ depends on AUFS
>+ depends on NFS_FS
>+ depends on !AUFS_FAKE_DM
>+ default n if (!AUFS_LHASH_PATCH || AUFS_FAKE_DM)
>+ default y

One AUFS_FAKE_DM is redundant here. It should probably be just


>+config AUFS_BR_XFS
>+ bool
>+ depends on AUFS
>+ depends on XFS_FS
>+ default y

Same here, just depends on XFS_FS.

>+ bool "Special handling for FUSE-based filesystem"
>+ depends on AUFS && FUSE_FS
>+ default n
>+ help
>+ A FUSE-based filesystem may not initialize its inode
>+ attributes and the FUSE developer thinks the inode attributes
>+ in a positive dentry which is returned by VFS lookup operation
>+ are not reliable.
>+ If you use a FUSE-based filesystem as an aufs branch, and it
>+ customizes the inode attribute on it without overriding
>+ fuse_lowlevel_ops.lookup, probably you need to enable this
>+ configuration.
>+ If you enable this configuration, aufs calls getattr operation
>+ in every lookup and revalidate operation for the FUSE-based
>+ filesystem branch.
>+ It will damage the performance even if you don't use a
>+ FUSE-based filesystem branch.

Performance is not "damaged" but "hurt" :-) [or just "will negatively
impact performance"]

>+ bool
>+ depends on AUFS
>+ depends on AUFS_DEBUG
>+ depends on MAGIC_SYSRQ
>+ default y

Since I see this for the first time, a bit of help text would not be
bad, even if it is not visible in menuconfig.

>+config AUFS_COMPAT
>+ bool "Compatibility with Unionfs (obsolete)"

If it is obsolete, it should not be merged.
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