I am sponsoring the following fast-track for Alan Wright. It
introduces a new property on ZFS datasets to improve support SMB
clients.
Requested binding is micro, timeout is 3/4/2009.
Template Version: @(#)sac_nextcase 1.68 02/23/09 SMI
This information is Copyright 2009 Sun Microsystems
1. Introduction
1.1. Project/Component Working Name:
ZFS dataset property to support SMB
1.2. Name of Document Author/Supplier:
Author: Alan Wright
1.3 Date of This Document:
26 February, 2009
4. Technical Description
This case proposes a new property for ZFS datasets, primarily to
support Windows interoperability, based on the following RFEs.
6808472 SMB name space caching on clients
Name space caching allows SMB clients to cache the directory and
file layout on a server. All of the caching logistics are handled
by the clients. On the server-side, the requirement is that the
server does not generate short names for files on the specified
file system; short names are the DOS 8.3 compatibility names that
are either space padded or contain an abbreviated form of a long
name with a '~'. Short names are generated by the server and
only the server can decipher them thus the client may be unable
to associate a short name with the original name in its cache.
In SMB terms, the server must generate unique names, which requires
a dataset-wide property to ensure that short names are not generated
on any share of a dataset on which name space caching is permitted.
6582167 Drive letter and volume label support
Windows allows volumes to be named and some Windows applications
embed the volume name in files, which can cause problems after
network volume migration from, say, Samba to the CIFS service.
For example, the Thumbs Plus photo indexing application keeps
track of non-local volumes by volume label since network drives
can show up on different drive letters. After switching from
Samba to the CIFS service, the volume label changed, which
invalidated the Thumbs Plus application database containing all
the keyword-to-image mapping information. It is desirable to
provide a property to allow users to label a ZFS dataset.
Server-side drive letters are required by some over-the-wire Windows
backup applications. When these applications convert a share name
to the absolute path on the server the path must be prefixed by a
server-side drive letter.
6600891 Need to be able to enable/disable oplocks per ZFS dataset
Opportunistic locks (oplocks) are used to coordinate SMB delegation,
which must be consistent across a dataset to ensure file content
integrity. Delegation is a mechanism for managing exclusive or
shared network access to files. For example, a client that has
been granted exclusive access to a file can cache the file content
locally, secure in the knowledge it will be informed if another
client or a server process tries to access the file, and it will be
given an opportunity to sync locally cached data back to the server
prior to another access being granted.
The proposed property is smb. The default value will be none.
The property is inherited, but individual values have different
inheritance rules as described below. Non-inherited values are
stripped out by libzfs before being passed to higher level
software.
The following values are defined:
shortnames=enabled | disabled
Controls whether or not short names will be generated for
objects in this file system. When the value is set to
disabled, the CIFS service will not generate short names
and indicate to SMB clients that name space caching is
allowed. Otherwise, the CIFS service will generate short
names and will not indicate that name space caching is
allowed. Short names will be generated by default. This
is an inheritable value.
label=[<drive-letter>:]name
Specifies a name for this file system. The name cannot
contain control characters (values 0x00 through 0x31) or
any of the following characters:
< > : " / \ | ? * ,
Optionally, the name may be prefixed by an alphabetic
character (drive letter) and a colon. The drive letter
may be used by clients as an alias for the volume name.
The default value of the label property will be the final
component of the mountpoint property, and there is no
requirement for the label to be unique on the server.
This is a non-inheritable value.
oplocks=enabled | disabled
Controls whether or not opportunistic locks (oplocks) will
be granted on this file system. The default value will be
enabled. This is an inheritable value.
Example
The following command disables short name and specifies a
label for the dataset. The oplocks value is not specified
and will default to enabled. The property as inherited by
children will appear as simply 'shortnames=disabled'.
# zfs set smb=shortnames=disabled,label=mylabel
6. Resources and Schedule
6.4. Steering Committee requested information
6.4.1. Consolidation C-team Name:
ON
6.5. ARC review type: FastTrack
6.6. ARC Exposure: open
