2 files changed, 18 insertions, 3 deletions

diff --git a/include/linux/nfs_page.h b/include/linux/nfs_page.h
index 479c566c4ddc..3eb072dbce83 100644
--- a/include/linux/nfs_page.h
+++ b/include/linux/nfs_page.h
@@ -58,6 +58,8 @@ struct nfs_pageio_ops {
         size_t  (*pg_test)(struct nfs_pageio_descriptor *, struct nfs_page *,
                            struct nfs_page *);
         int     (*pg_doio)(struct nfs_pageio_descriptor *);
+        unsigned int    (*pg_get_mirror_count)(struct nfs_pageio_descriptor *,
+                                       struct nfs_page *);
         void    (*pg_cleanup)(struct nfs_pageio_descriptor *);
 };
 
@@ -74,15 +76,17 @@ struct nfs_rw_ops {
                             struct rpc_task_setup *, int);
 };
 
-struct nfs_pageio_descriptor {
+struct nfs_pgio_mirror {
         struct list_head        pg_list;
         unsigned long           pg_bytes_written;
         size_t                  pg_count;
         size_t                  pg_bsize;
         unsigned int            pg_base;
-        unsigned char           pg_moreio : 1,
-                                pg_recoalesce : 1;
+        unsigned char           pg_recoalesce : 1;
+};
 
+struct nfs_pageio_descriptor {
+        unsigned char           pg_moreio : 1;
         struct inode            *pg_inode;
         const struct nfs_pageio_ops *pg_ops;
         const struct nfs_rw_ops *pg_rw_ops;
@@ -93,8 +97,18 @@ struct nfs_pageio_descriptor {
         struct pnfs_layout_segment *pg_lseg;
         struct nfs_direct_req   *pg_dreq;
         void                    *pg_layout_private;
+        unsigned int            pg_bsize;       /* default bsize for mirrors */
+
+        u32                     pg_mirror_count;
+        struct nfs_pgio_mirror  *pg_mirrors;
+        struct nfs_pgio_mirror  pg_mirrors_static[1];
+        struct nfs_pgio_mirror  *pg_mirrors_dynamic;
+        u32                     pg_mirror_idx;  /* current mirror */
 };
 
+/* arbitrarily selected limit to number of mirrors */
+#define NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX 16
+
 #define NFS_WBACK_BUSY(req)     (test_bit(PG_BUSY,&(req)->wb_flags))
 
 extern  struct nfs_page *nfs_create_request(struct nfs_open_context *ctx,
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 5bc99f04a550..6400a1e01aa4 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1329,6 +1329,7 @@ struct nfs_pgio_header {
         struct nfs_page_array   page_array;
         struct nfs_client       *ds_clp;        /* pNFS data server */
         int                     ds_commit_idx;  /* ds index if ds_clp is set */
+        int                     pgio_mirror_idx;/* mirror index in pgio layer */
 };
 
 struct nfs_mds_commit_info {