7 files changed, 293 insertions, 64 deletions

diff --git a/fs/nfs/direct.c b/fs/nfs/direct.c
index 1ee41d74c31c..0178d4fe8ab7 100644
--- a/fs/nfs/direct.c
+++ b/fs/nfs/direct.c
@@ -360,8 +360,14 @@ static void nfs_direct_read_completion(struct nfs_pgio_header *hdr)
         spin_lock(&dreq->lock);
         if (test_bit(NFS_IOHDR_ERROR, &hdr->flags) && (hdr->good_bytes == 0))
                 dreq->error = hdr->error;
-        else
-                dreq->count += hdr->good_bytes;
+        else {
+                /*
+                 * FIXME: right now this only accounts for bytes written
+                 *        to the first mirror
+                 */
+                if (hdr->pgio_mirror_idx == 0)
+                        dreq->count += hdr->good_bytes;
+        }
         spin_unlock(&dreq->lock);
 
         while (!list_empty(&hdr->pages)) {
@@ -724,7 +730,12 @@ static void nfs_direct_write_completion(struct nfs_pgio_header *hdr)
                 dreq->error = hdr->error;
         }
         if (dreq->error == 0) {
-                dreq->count += hdr->good_bytes;
+                /*
+                 * FIXME: right now this only accounts for bytes written
+                 *        to the first mirror
+                 */
+                if (hdr->pgio_mirror_idx == 0)
+                        dreq->count += hdr->good_bytes;
                 if (nfs_write_need_commit(hdr)) {
                         if (dreq->flags == NFS_ODIRECT_RESCHED_WRITES)
                                 request_commit = true;
diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h
index 05f9a87cdab4..ef1c703e487b 100644
--- a/fs/nfs/internal.h
+++ b/fs/nfs/internal.h
@@ -469,6 +469,7 @@ void nfs_init_cinfo(struct nfs_commit_info *cinfo,
                     struct nfs_direct_req *dreq);
 int nfs_key_timeout_notify(struct file *filp, struct inode *inode);
 bool nfs_ctx_key_to_expire(struct nfs_open_context *ctx);
+void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio);
 
 #ifdef CONFIG_MIGRATION
 extern int nfs_migrate_page(struct address_space *,
diff --git a/fs/nfs/objlayout/objio_osd.c b/fs/nfs/objlayout/objio_osd.c
index d00778077df1..9a5f2ee6001f 100644
--- a/fs/nfs/objlayout/objio_osd.c
+++ b/fs/nfs/objlayout/objio_osd.c
@@ -537,11 +537,12 @@ int objio_write_pagelist(struct nfs_pgio_header *hdr, int how)
 static size_t objio_pg_test(struct nfs_pageio_descriptor *pgio,
                           struct nfs_page *prev, struct nfs_page *req)
 {
+        struct nfs_pgio_mirror *mirror = &pgio->pg_mirrors[pgio->pg_mirror_idx];
         unsigned int size;
 
         size = pnfs_generic_pg_test(pgio, prev, req);
 
-        if (!size || pgio->pg_count + req->wb_bytes >
+        if (!size || mirror->pg_count + req->wb_bytes >
             (unsigned long)pgio->pg_layout_private)
                 return 0;
 
diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c
index 1c031878c752..eec12b75c232 100644
--- a/fs/nfs/pagelist.c
+++ b/fs/nfs/pagelist.c
@@ -46,17 +46,22 @@ void nfs_pgheader_init(struct nfs_pageio_descriptor *desc,
                        struct nfs_pgio_header *hdr,
                        void (*release)(struct nfs_pgio_header *hdr))
 {
-        hdr->req = nfs_list_entry(desc->pg_list.next);
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
+
+        hdr->req = nfs_list_entry(mirror->pg_list.next);
         hdr->inode = desc->pg_inode;
         hdr->cred = hdr->req->wb_context->cred;
         hdr->io_start = req_offset(hdr->req);
-        hdr->good_bytes = desc->pg_count;
+        hdr->good_bytes = mirror->pg_count;
         hdr->dreq = desc->pg_dreq;
         hdr->layout_private = desc->pg_layout_private;
         hdr->release = release;
         hdr->completion_ops = desc->pg_completion_ops;
         if (hdr->completion_ops->init_hdr)
                 hdr->completion_ops->init_hdr(hdr);
+
+        hdr->pgio_mirror_idx = desc->pg_mirror_idx;
 }
 EXPORT_SYMBOL_GPL(nfs_pgheader_init);
 
@@ -480,7 +485,10 @@ nfs_wait_on_request(struct nfs_page *req)
 size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
                            struct nfs_page *prev, struct nfs_page *req)
 {
-        if (desc->pg_count > desc->pg_bsize) {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
+
+        if (mirror->pg_count > mirror->pg_bsize) {
                 /* should never happen */
                 WARN_ON_ONCE(1);
                 return 0;
@@ -490,11 +498,11 @@ size_t nfs_generic_pg_test(struct nfs_pageio_descriptor *desc,
          * Limit the request size so that we can still allocate a page array
          * for it without upsetting the slab allocator.
          */
-        if (((desc->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
+        if (((mirror->pg_count + req->wb_bytes) >> PAGE_SHIFT) *
                         sizeof(struct page) > PAGE_SIZE)
                 return 0;
 
-        return min(desc->pg_bsize - desc->pg_count, (size_t)req->wb_bytes);
+        return min(mirror->pg_bsize - mirror->pg_count, (size_t)req->wb_bytes);
 }
 EXPORT_SYMBOL_GPL(nfs_generic_pg_test);
 
@@ -651,10 +659,18 @@ EXPORT_SYMBOL_GPL(nfs_initiate_pgio);
 static int nfs_pgio_error(struct nfs_pageio_descriptor *desc,
                           struct nfs_pgio_header *hdr)
 {
+        struct nfs_pgio_mirror *mirror;
+        u32 midx;
+
         set_bit(NFS_IOHDR_REDO, &hdr->flags);
         nfs_pgio_data_destroy(hdr);
         hdr->completion_ops->completion(hdr);
-        desc->pg_completion_ops->error_cleanup(&desc->pg_list);
+        /* TODO: Make sure it's right to clean up all mirrors here
+         *       and not just hdr->pgio_mirror_idx */
+        for (midx = 0; midx < desc->pg_mirror_count; midx++) {
+                mirror = &desc->pg_mirrors[midx];
+                desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
+        }
         return -ENOMEM;
 }
 
@@ -671,6 +687,17 @@ static void nfs_pgio_release(void *calldata)
         hdr->completion_ops->completion(hdr);
 }
 
+static void nfs_pageio_mirror_init(struct nfs_pgio_mirror *mirror,
+                                   unsigned int bsize)
+{
+        INIT_LIST_HEAD(&mirror->pg_list);
+        mirror->pg_bytes_written = 0;
+        mirror->pg_count = 0;
+        mirror->pg_bsize = bsize;
+        mirror->pg_base = 0;
+        mirror->pg_recoalesce = 0;
+}
+
 /**
  * nfs_pageio_init - initialise a page io descriptor
  * @desc: pointer to descriptor
@@ -687,13 +714,10 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
                      size_t bsize,
                      int io_flags)
 {
-        INIT_LIST_HEAD(&desc->pg_list);
-        desc->pg_bytes_written = 0;
-        desc->pg_count = 0;
-        desc->pg_bsize = bsize;
-        desc->pg_base = 0;
+        struct nfs_pgio_mirror *new;
+        int i;
+
         desc->pg_moreio = 0;
-        desc->pg_recoalesce = 0;
         desc->pg_inode = inode;
         desc->pg_ops = pg_ops;
         desc->pg_completion_ops = compl_ops;
@@ -703,6 +727,26 @@ void nfs_pageio_init(struct nfs_pageio_descriptor *desc,
         desc->pg_lseg = NULL;
         desc->pg_dreq = NULL;
         desc->pg_layout_private = NULL;
+        desc->pg_bsize = bsize;
+
+        desc->pg_mirror_count = 1;
+        desc->pg_mirror_idx = 0;
+
+        if (pg_ops->pg_get_mirror_count) {
+                /* until we have a request, we don't have an lseg and no
+                 * idea how many mirrors there will be */
+                new = kcalloc(NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX,
+                              sizeof(struct nfs_pgio_mirror), GFP_KERNEL);
+                desc->pg_mirrors_dynamic = new;
+                desc->pg_mirrors = new;
+
+                for (i = 0; i < NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX; i++)
+                        nfs_pageio_mirror_init(&desc->pg_mirrors[i], bsize);
+        } else {
+                desc->pg_mirrors_dynamic = NULL;
+                desc->pg_mirrors = desc->pg_mirrors_static;
+                nfs_pageio_mirror_init(&desc->pg_mirrors[0], bsize);
+        }
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_init);
 
@@ -738,14 +782,16 @@ static void nfs_pgio_result(struct rpc_task *task, void *calldata)
 int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
                      struct nfs_pgio_header *hdr)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
         struct nfs_page         *req;
         struct page             **pages,
                                 *last_page;
-        struct list_head *head = &desc->pg_list;
+        struct list_head *head = &mirror->pg_list;
         struct nfs_commit_info cinfo;
         unsigned int pagecount, pageused;
 
-        pagecount = nfs_page_array_len(desc->pg_base, desc->pg_count);
+        pagecount = nfs_page_array_len(mirror->pg_base, mirror->pg_count);
         if (!nfs_pgarray_set(&hdr->page_array, pagecount))
                 return nfs_pgio_error(desc, hdr);
 
@@ -773,7 +819,7 @@ int nfs_generic_pgio(struct nfs_pageio_descriptor *desc,
                 desc->pg_ioflags &= ~FLUSH_COND_STABLE;
 
         /* Set up the argument struct */
-        nfs_pgio_rpcsetup(hdr, desc->pg_count, 0, desc->pg_ioflags, &cinfo);
+        nfs_pgio_rpcsetup(hdr, mirror->pg_count, 0, desc->pg_ioflags, &cinfo);
         desc->pg_rpc_callops = &nfs_pgio_common_ops;
         return 0;
 }
@@ -781,12 +827,17 @@ EXPORT_SYMBOL_GPL(nfs_generic_pgio);
 
 static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
 {
+        struct nfs_pgio_mirror *mirror;
         struct nfs_pgio_header *hdr;
         int ret;
 
+        mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
         if (!hdr) {
-                desc->pg_completion_ops->error_cleanup(&desc->pg_list);
+                /* TODO: make sure this is right with mirroring - or
+                 *       should it back out all mirrors? */
+                desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
                 return -ENOMEM;
         }
         nfs_pgheader_init(desc, hdr, nfs_pgio_header_free);
@@ -801,6 +852,49 @@ static int nfs_generic_pg_pgios(struct nfs_pageio_descriptor *desc)
         return ret;
 }
 
+/*
+ * nfs_pageio_setup_mirroring - determine if mirroring is to be used
+ *                              by calling the pg_get_mirror_count op
+ */
+static int nfs_pageio_setup_mirroring(struct nfs_pageio_descriptor *pgio,
+                                       struct nfs_page *req)
+{
+        int mirror_count = 1;
+
+        if (!pgio->pg_ops->pg_get_mirror_count)
+                return 0;
+
+        mirror_count = pgio->pg_ops->pg_get_mirror_count(pgio, req);
+
+        if (!mirror_count || mirror_count > NFS_PAGEIO_DESCRIPTOR_MIRROR_MAX)
+                return -EINVAL;
+
+        if (WARN_ON_ONCE(!pgio->pg_mirrors_dynamic))
+                return -EINVAL;
+
+        pgio->pg_mirror_count = mirror_count;
+
+        return 0;
+}
+
+/*
+ * nfs_pageio_stop_mirroring - stop using mirroring (set mirror count to 1)
+ */
+void nfs_pageio_stop_mirroring(struct nfs_pageio_descriptor *pgio)
+{
+        pgio->pg_mirror_count = 1;
+        pgio->pg_mirror_idx = 0;
+}
+
+static void nfs_pageio_cleanup_mirroring(struct nfs_pageio_descriptor *pgio)
+{
+        pgio->pg_mirror_count = 1;
+        pgio->pg_mirror_idx = 0;
+        pgio->pg_mirrors = pgio->pg_mirrors_static;
+        kfree(pgio->pg_mirrors_dynamic);
+        pgio->pg_mirrors_dynamic = NULL;
+}
+
 static bool nfs_match_open_context(const struct nfs_open_context *ctx1,
                 const struct nfs_open_context *ctx2)
 {
@@ -867,19 +961,22 @@ static bool nfs_can_coalesce_requests(struct nfs_page *prev,
 static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
                                      struct nfs_page *req)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
         struct nfs_page *prev = NULL;
-        if (desc->pg_count != 0) {
-                prev = nfs_list_entry(desc->pg_list.prev);
+
+        if (mirror->pg_count != 0) {
+                prev = nfs_list_entry(mirror->pg_list.prev);
         } else {
                 if (desc->pg_ops->pg_init)
                         desc->pg_ops->pg_init(desc, req);
-                desc->pg_base = req->wb_pgbase;
+                mirror->pg_base = req->wb_pgbase;
         }
         if (!nfs_can_coalesce_requests(prev, req, desc))
                 return 0;
         nfs_list_remove_request(req);
-        nfs_list_add_request(req, &desc->pg_list);
-        desc->pg_count += req->wb_bytes;
+        nfs_list_add_request(req, &mirror->pg_list);
+        mirror->pg_count += req->wb_bytes;
         return 1;
 }
 
@@ -888,16 +985,19 @@ static int nfs_pageio_do_add_request(struct nfs_pageio_descriptor *desc,
  */
 static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 {
-        if (!list_empty(&desc->pg_list)) {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
+
+        if (!list_empty(&mirror->pg_list)) {
                 int error = desc->pg_ops->pg_doio(desc);
                 if (error < 0)
                         desc->pg_error = error;
                 else
-                        desc->pg_bytes_written += desc->pg_count;
+                        mirror->pg_bytes_written += mirror->pg_count;
         }
-        if (list_empty(&desc->pg_list)) {
-                desc->pg_count = 0;
-                desc->pg_base = 0;
+        if (list_empty(&mirror->pg_list)) {
+                mirror->pg_count = 0;
+                mirror->pg_base = 0;
         }
 }
 
@@ -915,10 +1015,14 @@ static void nfs_pageio_doio(struct nfs_pageio_descriptor *desc)
 static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
                            struct nfs_page *req)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
         struct nfs_page *subreq;
         unsigned int bytes_left = 0;
         unsigned int offset, pgbase;
 
+        WARN_ON_ONCE(desc->pg_mirror_idx >= desc->pg_mirror_count);
+
         nfs_page_group_lock(req, false);
 
         subreq = req;
@@ -938,7 +1042,7 @@ static int __nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
                         nfs_pageio_doio(desc);
                         if (desc->pg_error < 0)
                                 return 0;
-                        if (desc->pg_recoalesce)
+                        if (mirror->pg_recoalesce)
                                 return 0;
                         /* retry add_request for this subreq */
                         nfs_page_group_lock(req, false);
@@ -976,14 +1080,16 @@ err_ptr:
 
 static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
         LIST_HEAD(head);
 
         do {
-                list_splice_init(&desc->pg_list, &head);
-                desc->pg_bytes_written -= desc->pg_count;
-                desc->pg_count = 0;
-                desc->pg_base = 0;
-                desc->pg_recoalesce = 0;
+                list_splice_init(&mirror->pg_list, &head);
+                mirror->pg_bytes_written -= mirror->pg_count;
+                mirror->pg_count = 0;
+                mirror->pg_base = 0;
+                mirror->pg_recoalesce = 0;
+
                 desc->pg_moreio = 0;
 
                 while (!list_empty(&head)) {
@@ -997,11 +1103,11 @@ static int nfs_do_recoalesce(struct nfs_pageio_descriptor *desc)
                                 return 0;
                         break;
                 }
-        } while (desc->pg_recoalesce);
+        } while (mirror->pg_recoalesce);
         return 1;
 }
 
-int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+static int nfs_pageio_add_request_mirror(struct nfs_pageio_descriptor *desc,
                 struct nfs_page *req)
 {
         int ret;
@@ -1014,9 +1120,78 @@ int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
                         break;
                 ret = nfs_do_recoalesce(desc);
         } while (ret);
+
         return ret;
 }
 
+int nfs_pageio_add_request(struct nfs_pageio_descriptor *desc,
+                           struct nfs_page *req)
+{
+        u32 midx;
+        unsigned int pgbase, offset, bytes;
+        struct nfs_page *dupreq, *lastreq;
+
+        pgbase = req->wb_pgbase;
+        offset = req->wb_offset;
+        bytes = req->wb_bytes;
+
+        nfs_pageio_setup_mirroring(desc, req);
+
+        for (midx = 0; midx < desc->pg_mirror_count; midx++) {
+                if (midx) {
+                        nfs_page_group_lock(req, false);
+
+                        /* find the last request */
+                        for (lastreq = req->wb_head;
+                             lastreq->wb_this_page != req->wb_head;
+                             lastreq = lastreq->wb_this_page)
+                                ;
+
+                        dupreq = nfs_create_request(req->wb_context,
+                                        req->wb_page, lastreq, pgbase, bytes);
+
+                        if (IS_ERR(dupreq)) {
+                                nfs_page_group_unlock(req);
+                                return 0;
+                        }
+
+                        nfs_lock_request(dupreq);
+                        nfs_page_group_unlock(req);
+                        dupreq->wb_offset = offset;
+                        dupreq->wb_index = req->wb_index;
+                } else
+                        dupreq = req;
+
+                desc->pg_mirror_idx = midx;
+                if (!nfs_pageio_add_request_mirror(desc, dupreq))
+                        return 0;
+        }
+
+        return 1;
+}
+
+/*
+ * nfs_pageio_complete_mirror - Complete I/O on the current mirror of an
+ *                              nfs_pageio_descriptor
+ * @desc: pointer to io descriptor
+ */
+static void nfs_pageio_complete_mirror(struct nfs_pageio_descriptor *desc,
+                                       u32 mirror_idx)
+{
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[mirror_idx];
+        u32 restore_idx = desc->pg_mirror_idx;
+
+        desc->pg_mirror_idx = mirror_idx;
+        for (;;) {
+                nfs_pageio_doio(desc);
+                if (!mirror->pg_recoalesce)
+                        break;
+                if (!nfs_do_recoalesce(desc))
+                        break;
+        }
+        desc->pg_mirror_idx = restore_idx;
+}
+
 /*
  * nfs_pageio_resend - Transfer requests to new descriptor and resend
  * @hdr - the pgio header to move request from
@@ -1055,16 +1230,14 @@ EXPORT_SYMBOL_GPL(nfs_pageio_resend);
  */
 void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
 {
-        for (;;) {
-                nfs_pageio_doio(desc);
-                if (!desc->pg_recoalesce)
-                        break;
-                if (!nfs_do_recoalesce(desc))
-                        break;
-        }
+        u32 midx;
+
+        for (midx = 0; midx < desc->pg_mirror_count; midx++)
+                nfs_pageio_complete_mirror(desc, midx);
 
         if (desc->pg_ops->pg_cleanup)
                 desc->pg_ops->pg_cleanup(desc);
+        nfs_pageio_cleanup_mirroring(desc);
 }
 
 /**
@@ -1080,10 +1253,17 @@ void nfs_pageio_complete(struct nfs_pageio_descriptor *desc)
  */
 void nfs_pageio_cond_complete(struct nfs_pageio_descriptor *desc, pgoff_t index)
 {
-        if (!list_empty(&desc->pg_list)) {
-                struct nfs_page *prev = nfs_list_entry(desc->pg_list.prev);
-                if (index != prev->wb_index + 1)
-                        nfs_pageio_complete(desc);
+        struct nfs_pgio_mirror *mirror;
+        struct nfs_page *prev;
+        u32 midx;
+
+        for (midx = 0; midx < desc->pg_mirror_count; midx++) {
+                mirror = &desc->pg_mirrors[midx];
+                if (!list_empty(&mirror->pg_list)) {
+                        prev = nfs_list_entry(mirror->pg_list.prev);
+                        if (index != prev->wb_index + 1)
+                                nfs_pageio_complete_mirror(desc, midx);
+                }
         }
 }
 
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 2da2e771fefe..5f7c422ebb5d 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -1646,8 +1646,8 @@ EXPORT_SYMBOL_GPL(pnfs_generic_pg_cleanup);
  * of bytes (maximum @req->wb_bytes) that can be coalesced.
  */
 size_t
-pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio, struct nfs_page *prev,
-                     struct nfs_page *req)
+pnfs_generic_pg_test(struct nfs_pageio_descriptor *pgio,
+                     struct nfs_page *prev, struct nfs_page *req)
 {
         unsigned int size;
         u64 seg_end, req_start, seg_left;
@@ -1729,10 +1729,12 @@ static void
 pnfs_write_through_mds(struct nfs_pageio_descriptor *desc,
                 struct nfs_pgio_header *hdr)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
         if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
-                list_splice_tail_init(&hdr->pages, &desc->pg_list);
+                list_splice_tail_init(&hdr->pages, &mirror->pg_list);
                 nfs_pageio_reset_write_mds(desc);
-                desc->pg_recoalesce = 1;
+                mirror->pg_recoalesce = 1;
         }
         nfs_pgio_data_destroy(hdr);
 }
@@ -1781,12 +1783,14 @@ EXPORT_SYMBOL_GPL(pnfs_writehdr_free);
 int
 pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
         struct nfs_pgio_header *hdr;
         int ret;
 
         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
         if (!hdr) {
-                desc->pg_completion_ops->error_cleanup(&desc->pg_list);
+                desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
                 return -ENOMEM;
         }
         nfs_pgheader_init(desc, hdr, pnfs_writehdr_free);
@@ -1795,6 +1799,7 @@ pnfs_generic_pg_writepages(struct nfs_pageio_descriptor *desc)
         ret = nfs_generic_pgio(desc, hdr);
         if (!ret)
                 pnfs_do_write(desc, hdr, desc->pg_ioflags);
+
         return ret;
 }
 EXPORT_SYMBOL_GPL(pnfs_generic_pg_writepages);
@@ -1839,10 +1844,13 @@ static void
 pnfs_read_through_mds(struct nfs_pageio_descriptor *desc,
                 struct nfs_pgio_header *hdr)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
+
         if (!test_and_set_bit(NFS_IOHDR_REDO, &hdr->flags)) {
-                list_splice_tail_init(&hdr->pages, &desc->pg_list);
+                list_splice_tail_init(&hdr->pages, &mirror->pg_list);
                 nfs_pageio_reset_read_mds(desc);
-                desc->pg_recoalesce = 1;
+                mirror->pg_recoalesce = 1;
         }
         nfs_pgio_data_destroy(hdr);
 }
@@ -1893,12 +1901,14 @@ EXPORT_SYMBOL_GPL(pnfs_readhdr_free);
 int
 pnfs_generic_pg_readpages(struct nfs_pageio_descriptor *desc)
 {
+        struct nfs_pgio_mirror *mirror = &desc->pg_mirrors[desc->pg_mirror_idx];
+
         struct nfs_pgio_header *hdr;
         int ret;
 
         hdr = nfs_pgio_header_alloc(desc->pg_rw_ops);
         if (!hdr) {
-                desc->pg_completion_ops->error_cleanup(&desc->pg_list);
+                desc->pg_completion_ops->error_cleanup(&mirror->pg_list);
                 return -ENOMEM;
         }
         nfs_pgheader_init(desc, hdr, pnfs_readhdr_free);
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 092ab499f2b6..568ecf0a880f 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -70,8 +70,15 @@ EXPORT_SYMBOL_GPL(nfs_pageio_init_read);
 
 void nfs_pageio_reset_read_mds(struct nfs_pageio_descriptor *pgio)
 {
+        struct nfs_pgio_mirror *mirror;
+
         pgio->pg_ops = &nfs_pgio_rw_ops;
-        pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
+
+        /* read path should never have more than one mirror */
+        WARN_ON_ONCE(pgio->pg_mirror_count != 1);
+
+        mirror = &pgio->pg_mirrors[0];
+        mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->rsize;
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_reset_read_mds);
 
@@ -81,6 +88,7 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
         struct nfs_page *new;
         unsigned int len;
         struct nfs_pageio_descriptor pgio;
+        struct nfs_pgio_mirror *pgm;
 
         len = nfs_page_length(page);
         if (len == 0)
@@ -97,7 +105,13 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
                              &nfs_async_read_completion_ops);
         nfs_pageio_add_request(&pgio, new);
         nfs_pageio_complete(&pgio);
-        NFS_I(inode)->read_io += pgio.pg_bytes_written;
+
+        /* It doesn't make sense to do mirrored reads! */
+        WARN_ON_ONCE(pgio.pg_mirror_count != 1);
+
+        pgm = &pgio.pg_mirrors[0];
+        NFS_I(inode)->read_io += pgm->pg_bytes_written;
+
         return 0;
 }
 
@@ -352,6 +366,7 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
                 struct list_head *pages, unsigned nr_pages)
 {
         struct nfs_pageio_descriptor pgio;
+        struct nfs_pgio_mirror *pgm;
         struct nfs_readdesc desc = {
                 .pgio = &pgio,
         };
@@ -387,10 +402,15 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
                              &nfs_async_read_completion_ops);
 
         ret = read_cache_pages(mapping, pages, readpage_async_filler, &desc);
-
         nfs_pageio_complete(&pgio);
-        NFS_I(inode)->read_io += pgio.pg_bytes_written;
-        npages = (pgio.pg_bytes_written + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;
+
+        /* It doesn't make sense to do mirrored reads! */
+        WARN_ON_ONCE(pgio.pg_mirror_count != 1);
+
+        pgm = &pgio.pg_mirrors[0];
+        NFS_I(inode)->read_io += pgm->pg_bytes_written;
+        npages = (pgm->pg_bytes_written + PAGE_CACHE_SIZE - 1) >>
+                 PAGE_CACHE_SHIFT;
         nfs_add_stats(inode, NFSIOS_READPAGES, npages);
 read_complete:
         put_nfs_open_context(desc.ctx);
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 2bee165fddcf..ceacfeeb28c2 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -906,7 +906,7 @@ static void nfs_write_completion(struct nfs_pgio_header *hdr)
                 if (nfs_write_need_commit(hdr)) {
                         memcpy(&req->wb_verf, &hdr->verf.verifier, sizeof(req->wb_verf));
                         nfs_mark_request_commit(req, hdr->lseg, &cinfo,
-                                0);
+                                hdr->pgio_mirror_idx);
                         goto next;
                 }
 remove_req:
@@ -1304,8 +1304,14 @@ EXPORT_SYMBOL_GPL(nfs_pageio_init_write);
 
 void nfs_pageio_reset_write_mds(struct nfs_pageio_descriptor *pgio)
 {
+        struct nfs_pgio_mirror *mirror;
+
         pgio->pg_ops = &nfs_pgio_rw_ops;
-        pgio->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
+
+        nfs_pageio_stop_mirroring(pgio);
+
+        mirror = &pgio->pg_mirrors[0];
+        mirror->pg_bsize = NFS_SERVER(pgio->pg_inode)->wsize;
 }
 EXPORT_SYMBOL_GPL(nfs_pageio_reset_write_mds);