1.TL
2Toward a Compatible Filesystem Interface
3.AU
4Michael J. Karels
5Marshall Kirk McKusick
6.AI
7Computer Systems Research Group
8Computer Science Division
9Department of Electrical Engineering and Computer Science
10University of California, Berkeley
11Berkeley, California  94720
12.LP
13As network or remote filesystems have been implemented for
14.UX ,
15several stylized interfaces between the filesystem implementation
16and the rest of the kernel have been developed.
17Notable among these are Sun Microsystems' virtual filesystem interface
18using vnodes, Digital Equipment's Generic File System architecture,
19and AT&T's File System Switch.
20Each design attempts to isolate filesystem-dependent details
21below the generic interface and to provide a framework within which
22new filesystems may be incorporated.
23However, each of these interfaces is different from
24and incompatible with the others.
25Each of them addresses somewhat different design goals.
26Each was based upon a different starting version of
27.UX ,
28targetted a different set of filesystems with varying characteristics,
29and uses a different set of primitive operations provided by the filesystem.
30The current study compares the various filesystem interfaces.
31Criteria for comparison include generality, completeness, robustness,
32efficiency and esthetics.
33As a result of this comparison, a proposal for a new filesystem interface
34is advanced that includes the best features of the existing implementations.
35The proposal adopts the calling convention for name lookup introduced
36in 4.3BSD.
37A prototype implementation is described.
38This proposal and the rationale underlying its development
39have been presented to major software vendors
40as an early step toward convergence upon a compatible filesystem interface.
41