As reported last week, many users had requested that the XFS filesystem be
added to the 2.4 kernel despite Marcelo's stated intent to go into a
maintenance-only mode. Those users have prevailed: Marcelo has announced
that, after a review by Christoph
Hellwig, XFS has been merged into his 2.4 tree. It will thus show up in
the first 2.4.24 prepatch, whenever that is released.
What has gone into 2.4 is, in fact, not the full XFS patch. Two subsystems
have been left out:
- DMAPI (Data Management API). This is an interface which allows the
filesystem to communicate with hierarchical storage management
- ACLs. Access control lists require more general extended attribute
support, which has never been merged into 2.4.
Users needing those features in XFS will have to run 2.6 to get them. Most
users, however, will most likely be happy with the core XFS filesystem.
Meanwhile, a new request has been heard: could the device mapper (LVM2)
code be merged? Marcelo's answer was
direct: "I believe 2.6 is the right place for the device
mapper." That would seem to be the end of the matter, but arguments
are now being marshalled to try to get Marcelo to change his mind. This posting by Kevin Corry covers the relevant
points quite well:
- LVM2 is a lot nicer. The user-space tools, many taken from IBM's
EVMS project, are easier to work with, and the device mapper code
provides many capabilities that simply are unavailable in LVM1.
- LVM1 itself has been removed from the 2.6 kernel (though LVM2 does
provide backward compatibility). Putting LVM2 into
2.4 would make the transition easier for LVM users; they could get
their volume sets working with LVM2 before having to commit to the new
The forward compatibility argument strikes a chord with many participants
in the discussion, but Marcelo is, for now, adamant. One never knows, though; he
previously has taken equally strong positions against ACPI and, of course,
XFS, but been won over in the end.
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