Messages in this thread | | | From | "Peter J. Braam" <> | Subject | [PATCH/RFC] Lustre VFS patch | Date | Mon, 24 May 2004 19:39:50 +0800 |
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Hi Linus, Andrew & others,
Many people have asked me to have this patched reviewed, and considered for inclusion in 2.6 after some reworking. At the kernel summit last summer we discussed these issues.
This patch is not the Lustre file system, with client file system, Lustre RPC, server code etc. This patch would enable people to run Lustre with modules loading into unmodified kernels and this appears to be something vendors really would like to see. FYI, at the moment Lustre is a just a little bit larger than NFS, comparing clients, servers, and rpc code for each (60K vs 80K lines of code).
This patch was written quite defensively: file systems not using intents should really be completely unaffected.
I attach a little tar ball with patches and a series file which describes the order of the patches. Below is a short description of each of the patches. I also want to tell you a few things we have worked on that are not present in this patch:
- deal with "pinning" directories that are CWD or mount points. They should not be removable/unlinkable by remote nodes, and the FS needs some indication of that.
- in Lustre d_parent is not necessarily valid, so sys_getcwd needs to be careful. In Ottawa we discussed adding an optional hook.
- changes to NFSD to allow it to run on top of Lustre
- per file system locking operations (refinining i_sem) to allow parallel updates in one directory.
It goes without saying that many people in CFS have made contributions to this patch and that the ideas were heavily influenced by discussions with the kernel community.
Please give me your thoughts about how we can move forward with this.
Regards,
- Peter -
dev_read_only-vanilla-2.6.patch
This introduces an ioctl on block devices to stop doing I/O. The only purpose of the patch is automated recovery regression testing, it is very convenient to have this available.
export-vanilla-2.6.patch
Export symbols used by Lustre.
header_guards-vanilla-2.6.patch
Small bug fix to avoid double inclusion of headers
lustre_version.patch
A tiny header to check that the kernel patch and Lustre modules are compatible.
vfs-dcache_locking-vanilla-2.6.patch
A trivial patch to make functions available to lustre that do d_move, d_rehash, without taking/dropping the dcache lock.
vfs-dcache_lustre_invalid-vanilla-2.6.patch
This allows dentries to be d_invalidate'd if a bit is set in the FLAGS. This is required when dentries that are busy on the local node are invalidated on another client system.
vfs-intent_api-vanilla-2.6.patch
Introduce intents for other operations. Add a file system hook to release intent data. Make a few "intent versions" of functions such as "lookup_one_len_it" and "user_walk_it" available through headers. Arrange that the open intent is visible in the open methods. Add a few missing intent_init calls.
vfs-intent_exec-vanilla-2.6.patch
Add intents for open in the context of execution.
vfs-intent_init-vanilla-2.6.patch
Add intent_init for all operations, not just for open.
vfs-intent_lustre-vanilla-2.6.patch
Add a pointer to per fs intent_data structure to the struct lookup_intent.
vfs-raw_ops-vanilla-2.6.patch
This adds raw operations for setattr, mkdir, rmdir, mknod, unlink, symlink, link and rename. The raw operations look up the parent directories (but not leaf nodes) involved in the operation and then ask the file system to execute the operation. These methods allow us to delegate the execution of these functions to the server, and instantiate no dentries for leaf nodes, leaf nodes will only enter the dcache on subsequent lookups. This patch dramatically simplifies the client/server lock management, particularly for rename.
In Ottawa Linus suggested that we could maybe do this with intents instead. I feel that both are ugly, both are possible but intents looked akward.
vfs-revalidate_counter-vanilla-2.6.patch
We found that dentries could be invalidated multiple times through activity on remote nodes, but this shoudl not lead to failure in Lustre. The revalidation path real_lookup was adapted to take a few more iterations through the revalidation before giving up. This revalidation takes the form of first revalidating, then looking up if it fails, and possibly revalidating a few more times (see above) until there is success.
vfs-revalidate_special-vanilla-2.6.patch
We add nameidata flags to indicate that a link sits in the middle of the path and a flag that inidicates we are looking at the last component of a path. [If someone knows if the existing flags could detect this, that would be welcome.] To pass intents when the last pathname component is a "." we insert a "special" revalidation function that calls revalidate dentry when such a pathname is traversed.
vfs_intent-flags_rename-vanilla-2.6.patch
As Linus requested in Ottawa last summer, rename intent.open.flags to intent. it_flags and intent.open.create_mode to intent.it_create_mode. Remove the union of "intents", which only contained an open_intent, and replace it with a single struct lookup_intent included in the nameidata.
vfs-do_truncate.patch
We added a parameter to do_truncate so that the FS can now if it is being called from open or not.
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