Re: BSD XFS Port BSD VFS Rewrite
I'm not familiar with the VFS_default stuff. All the vop_default_desc routines in NetBSD point to error routines. In FreeBSD, they now point to default routines that are *not* error routines. This is the problem. I admit the change was very well intentioned, since it made the code a hell of a lot more readable, but choosing between readable and additional function, I take function over form (I think the way I would have "fixed" the readability is by making the operations that result in the descriptor set for a mounted FS instance be both discrete, and named for their specific function). As I recall most of FBSD's default routines are also error routines, if the exceptions were a problem it would would be trivial to fix. I think fixing resource allocation/deallocation for things like vnodes, cnbufs, and locks are a higher priority for now. There are examples such as in detached threading where it might make sense for the detached child to be responsible for releasing resources allocated to it by the parent, but in stacking this model is very messy and unnatural. This is why the purpose of VOP_ABORTOP appears to be to release cnbufs but this is really just an ugly side effect. With stacking the code that allocates should be the code that deallocates. Substitute, "code" with "layer" to be more correct. I fixed a lot of the vnode and locking cases, unfortunately the ones that remain are probably ugly cases where you have to reacquire locks that had to be unlocked somewhere in the executing layer. See VOP_RENAME for an example. Compare the number of WILLRELEs in vnode_if.src in FreeBSD and NetBSD, ideally there'd be none. Regards, Mike Hancock To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: BSD XFS Port BSD VFS Rewrite
On Tue, 17 Aug 1999, Bill Studenmund wrote: I've compared the two, and making the NetBSD number match the FreeBSD number is one of my goals. :-) Any suggestions, or just plodfix? It can be very cumbersome tracking down references being bumped by vref/VREF and other operations. Among the uncompleted operations are VOPs that pre-release the returned vpp to the caller. I think in VOP_MKNOD this was done as a convenience and you might have to add code to handle device vp aliases correctly. Just remember the rule, the allocating layer must be the layer that deallocates. Regards, Mike To Unsubscribe: send mail to [EMAIL PROTECTED] with "unsubscribe freebsd-hackers" in the body of the message
Re: BSD XFS Port BSD VFS Rewrite
I'm not familiar with the VFS_default stuff. All the vop_default_desc routines in NetBSD point to error routines. In FreeBSD, they now point to default routines that are *not* error routines. This is the problem. I admit the change was very well intentioned, since it made the code a hell of a lot more readable, but choosing between readable and additional function, I take function over form (I think the way I would have fixed the readability is by making the operations that result in the descriptor set for a mounted FS instance be both discrete, and named for their specific function). As I recall most of FBSD's default routines are also error routines, if the exceptions were a problem it would would be trivial to fix. I think fixing resource allocation/deallocation for things like vnodes, cnbufs, and locks are a higher priority for now. There are examples such as in detached threading where it might make sense for the detached child to be responsible for releasing resources allocated to it by the parent, but in stacking this model is very messy and unnatural. This is why the purpose of VOP_ABORTOP appears to be to release cnbufs but this is really just an ugly side effect. With stacking the code that allocates should be the code that deallocates. Substitute, code with layer to be more correct. I fixed a lot of the vnode and locking cases, unfortunately the ones that remain are probably ugly cases where you have to reacquire locks that had to be unlocked somewhere in the executing layer. See VOP_RENAME for an example. Compare the number of WILLRELEs in vnode_if.src in FreeBSD and NetBSD, ideally there'd be none. Regards, Mike Hancock To Unsubscribe: send mail to majord...@freebsd.org with unsubscribe freebsd-hackers in the body of the message
Re: BSD XFS Port BSD VFS Rewrite
On Tue, 17 Aug 1999, Bill Studenmund wrote: I've compared the two, and making the NetBSD number match the FreeBSD number is one of my goals. :-) Any suggestions, or just plodfix? It can be very cumbersome tracking down references being bumped by vref/VREF and other operations. Among the uncompleted operations are VOPs that pre-release the returned vpp to the caller. I think in VOP_MKNOD this was done as a convenience and you might have to add code to handle device vp aliases correctly. Just remember the rule, the allocating layer must be the layer that deallocates. Regards, Mike To Unsubscribe: send mail to majord...@freebsd.org with unsubscribe freebsd-hackers in the body of the message
Re: BSD XFS Port BSD VFS Rewrite
Have you tried Heidemann's student's stacking layers? There is one encryption, and one per-file compression with namespace hiding, that I think it would be hard pressed to keep up with. But I'll give it the benefit of the doubt. 8-). Nope. The problem is that while stacking (null, umap, and overlay fs's) work, we don't have the coherency issues worked out so that upper layers can cache data. i.e. so that the lower fs knows it has to ask the uper layers to give pages back. :-) But multiple ls -lR's work fine. :-) Interesting, have you read the Heidemann paper that outlines a solution that uses a cache manager? You can probably find it somewhere here, http://www.isi.edu/~johnh/SOFTWARE/UCLA_STACKING/ To Unsubscribe: send mail to majord...@freebsd.org with unsubscribe freebsd-hackers in the body of the message
Re: BSD XFS Port BSD VFS Rewrite
I forgot I had some old diffs that may be of help, http://www.freebsd.org/~mch/vop1a.diff You'll notice that just about everywhere that I moved vput() to the appropriate layer a path component buffer was also freed in the wrong place. John Dyson put these buffers in zones so the free routine probably looks very different than in netbsd. zfree(namei_zone, cnp-cn_pnbuf); - vput(dvp); Regards, Mike To Unsubscribe: send mail to majord...@freebsd.org with unsubscribe freebsd-hackers in the body of the message
