nfsd41: DRC save, restore, and clear functions

Cache all the result pages, including the rpc header in rq_respages[0],
for a request in the slot table cache entry.

Cache the statp pointer from nfsd_dispatch which points into rq_respages[0]
just past the rpc header. When setting a cache entry, calculate and save the
length of the nfs data minus the rpc header for rq_respages[0].

When replaying a cache entry, replace the cached rpc header with the
replayed request rpc result header, unless there is not enough room in the
cached results first page. In that case, use the cached rpc header.

The sessions fore channel maxresponse size cached is set to NFSD_PAGES_PER_SLOT
* PAGE_SIZE. For compounds we are cacheing with operations such as READDIR
that use the xdr_buf->pages to hold data, we choose to cache the extra page of
data rather than copying data from xdr_buf->pages into the xdr_buf->head page.

[nfsd41: limit cache to maxresponsesize_cached]
[nfsd41: mv nfsd4_set_statp under CONFIG_NFSD_V4_1]
[nfsd41: rename nfsd4_move_pages]
[nfsd41: rename page_no variable]
[nfsd41: rename nfsd4_set_cache_entry]
[nfsd41: fix nfsd41_copy_replay_data comment]
[nfsd41: add to nfsd4_set_cache_entry]
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>

1 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/nfsd/state.h b/include/linux/nfsd/state.h
index 90829db76861..f1edb1d98523 100644
--- a/include/linux/nfsd/state.h
+++ b/include/linux/nfsd/state.h
@@ -99,9 +99,22 @@ struct nfs4_callback {
         struct rpc_clnt *       cb_client;
 };
 
+/* Maximum number of pages per slot cache entry */
+#define NFSD_PAGES_PER_SLOT     1
+
+struct nfsd4_cache_entry {
+        __be32          ce_status;
+        struct kvec     ce_datav; /* encoded NFSv4.1 data in rq_res.head[0] */
+        struct page     *ce_respages[NFSD_PAGES_PER_SLOT + 1];
+        short           ce_resused;
+        int             ce_opcnt;
+        int             ce_rpchdrlen;
+};
+
 struct nfsd4_slot {
         bool                            sl_inuse;
         u32                             sl_seqid;
+        struct nfsd4_cache_entry        sl_cache_entry;
 };
 
 struct nfsd4_session {