[pnfs] [PATCH 0/38] [v1] pnfs: client layout cache

[Benny Halevy]

Seven updated patches and one new, based on (mostly Dean's) comments in replies
to this email.

Please get full updated patchset from git://linux-nfs.org/~bhalevy/linux-pnfs.git
client-layout-cache branch, or use "git-remote update" if you've already
cloned the tree.

updated 0016-pnfs-allocate-layout-driver-data-in-one-piece-with.patch
new     0017-pnfs-require-layout-driver-alloc-free-_layout.patch
updated 0019-pnfs-client-layout-cache-introduce-get_alloc_layou.patch
updated 0020-pnfs-client-layout-cache-allow-waiting-for-alloc_l.patch
updated 0021-pnfs-client-layout-cache-get_lock-put_unlock-_cur.patch
updated 0022-pnfs-client-layout-cache-unlock-layout-around-call.patch
updated 0025-pnfs-client-layout-cache-require-layout-driver-al.patch
updated 0038-pnfs-client-layout-cache-return_layout-use-pnfs_f.patch

Benny

On Jan. 01, 2008, 12:47 +0200, Benny Halevy <bhalevy at panasas.com> wrote:
> This patchset contains some cleanups and bug fixes to the existing pnfs code.
> Mainly support for non page cache I/O was removed since it's not used anywhere
> at the moment.  Rather than maintaining the dead code we rather add it back only
> if/when needed.
> 
> The client layout cache stores layout segments in a sorted list hung
> from struct pnfs_layout_type.
> 
> Allocation and deallocation of this structure was simplified allowing
> the layout driver to easily allocate its private data in one chunk
> immediately following the generic structure.
> 
> Same principle was applied for layout segment allocation.
> 
> New accessors help getting the LD private data, as well as "standard" pointers
> (e.g. nfs_inode, nfs_server, etc.) derived from pnfs_layout_type (and
> pnfs_layout_segment).  This allows simplifying the LD API a bit by
> passing it only the pnfs_layout_type without the inode.
> 
> Layout driver is no longer responsible for maintaining layout segments
> and it does not set the nfsi->current_layout to NULL when there's no
> more layout information to keep.  The pnfs layout cache is doing that
> by keeping track of all layout segments and maintaining them in sync
> with LAYOUTGETs and LAYOUTRETURNs.
> 
> The LD read, write, (and later-on commit) methods now get the
> layout segment covering the I/O byte range in the nfs_{read,write}_data
> structure and it is freed on exit for synchronous I/O or in the
> done function for the asynchronous paths.
> 
> To simplify async done processing the layout drivers must always set
> the rpc task.tk_status and result fields (count, eof for read, committed for
>  write) and then call back the pnfs nfs_{read,write}list_complete functions
> that will call up the rpc_call_done chain.  If the LD I/O function returns
> synchronously, it still must set the fields mentioned above.
> 
> I also added some basic synchronization and reference counting for allocating
> and using layout cache structures.  Higher level synchronization between layout
> gets, returns, and recalls is still to be done.
> 
> Benny
> 
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