5 files changed, 90 insertions, 25 deletions

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 77966ecb0a2c..86c154bad5db 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -30,6 +30,7 @@
 #include <linux/nfs_fs.h>
 #include "internal.h"
 #include "pnfs.h"
+#include "iostat.h"
 
 #define NFSDBG_FACILITY         NFSDBG_PNFS
 
@@ -880,6 +881,33 @@ pnfs_pageio_init_read(struct nfs_pageio_descriptor *pgio, struct inode *inode)
 }
 
 /*
+ * Call the appropriate parallel I/O subsystem read function.
+ */
+enum pnfs_try_status
+pnfs_try_to_read_data(struct nfs_read_data *rdata,
+                       const struct rpc_call_ops *call_ops)
+{
+        struct inode *inode = rdata->inode;
+        struct nfs_server *nfss = NFS_SERVER(inode);
+        enum pnfs_try_status trypnfs;
+
+        rdata->mds_ops = call_ops;
+
+        dprintk("%s: Reading ino:%lu %u@%llu\n",
+                __func__, inode->i_ino, rdata->args.count, rdata->args.offset);
+
+        trypnfs = nfss->pnfs_curr_ld->read_pagelist(rdata);
+        if (trypnfs == PNFS_NOT_ATTEMPTED) {
+                put_lseg(rdata->lseg);
+                rdata->lseg = NULL;
+        } else {
+                nfs_inc_stats(inode, NFSIOS_PNFS_READ);
+        }
+        dprintk("%s End (trypnfs:%d)\n", __func__, trypnfs);
+        return trypnfs;
+}
+
+/*
  * Device ID cache. Currently supports one layout type per struct nfs_client.
  * Add layout type to the lookup key to expand to support multiple types.
  */
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 5107d14db485..585023fabb55 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -45,6 +45,11 @@ struct pnfs_layout_segment {
         struct pnfs_layout_hdr *pls_layout;
 };
 
+enum pnfs_try_status {
+        PNFS_ATTEMPTED     = 0,
+        PNFS_NOT_ATTEMPTED = 1,
+};
+
 #ifdef CONFIG_NFS_V4_1
 
 #define LAYOUT_NFSV4_1_MODULE_PREFIX "nfs-layouttype4"
@@ -70,6 +75,12 @@ struct pnfs_layoutdriver_type {
 
         /* test for nfs page cache coalescing */
         int (*pg_test)(struct nfs_pageio_descriptor *, struct nfs_page *, struct nfs_page *);
+
+        /*
+         * Return PNFS_ATTEMPTED to indicate the layout code has attempted
+         * I/O, else return PNFS_NOT_ATTEMPTED to fall back to normal NFS
+         */
+        enum pnfs_try_status (*read_pagelist) (struct nfs_read_data *nfs_data);
 };
 
 struct pnfs_layout_hdr {
@@ -157,6 +168,8 @@ pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
                    enum pnfs_iomode access_type);
 void set_pnfs_layoutdriver(struct nfs_server *, u32 id);
 void unset_pnfs_layoutdriver(struct nfs_server *);
+enum pnfs_try_status pnfs_try_to_read_data(struct nfs_read_data *,
+                                            const struct rpc_call_ops *);
 void pnfs_pageio_init_read(struct nfs_pageio_descriptor *, struct inode *);
 int pnfs_layout_process(struct nfs4_layoutget *lgp);
 void pnfs_free_lseg_list(struct list_head *tmp_list);
@@ -227,6 +240,13 @@ pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
         return NULL;
 }
 
+static inline enum pnfs_try_status
+pnfs_try_to_read_data(struct nfs_read_data *data,
+                      const struct rpc_call_ops *call_ops)
+{
+        return PNFS_NOT_ATTEMPTED;
+}
+
 static inline bool
 pnfs_roc(struct inode *ino)
 {
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 6dc9eaf00e5c..4127a1c0eec6 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -18,6 +18,8 @@
 #include <linux/sunrpc/clnt.h>
 #include <linux/nfs_fs.h>
 #include <linux/nfs_page.h>
+#include <linux/smp_lock.h>
+#include <linux/module.h>
 
 #include <asm/system.h>
 #include "pnfs.h"
@@ -155,25 +157,20 @@ static void nfs_readpage_release(struct nfs_page *req)
         nfs_release_request(req);
 }
 
-/*
- * Set up the NFS read request struct
- */
-static int nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
-                const struct rpc_call_ops *call_ops,
-                unsigned int count, unsigned int offset,
-                struct pnfs_layout_segment *lseg)
+static int nfs_initiate_read(struct nfs_read_data *data, struct rpc_clnt *clnt,
+                      const struct rpc_call_ops *call_ops)
 {
-        struct inode *inode = req->wb_context->path.dentry->d_inode;
+        struct inode *inode = data->inode;
         int swap_flags = IS_SWAPFILE(inode) ? NFS_RPC_SWAPFLAGS : 0;
         struct rpc_task *task;
         struct rpc_message msg = {
                 .rpc_argp = &data->args,
                 .rpc_resp = &data->res,
-                .rpc_cred = req->wb_context->cred,
+                .rpc_cred = data->cred,
         };
         struct rpc_task_setup task_setup_data = {
                 .task = &data->task,
-                .rpc_client = NFS_CLIENT(inode),
+                .rpc_client = clnt,
                 .rpc_message = &msg,
                 .callback_ops = call_ops,
                 .callback_data = data,
@@ -181,9 +178,37 @@ static int nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
                 .flags = RPC_TASK_ASYNC | swap_flags,
         };
 
+        /* Set up the initial task struct. */
+        NFS_PROTO(inode)->read_setup(data, &msg);
+
+        dprintk("NFS: %5u initiated read call (req %s/%lld, %u bytes @ "
+                        "offset %llu)\n",
+                        data->task.tk_pid,
+                        inode->i_sb->s_id,
+                        (long long)NFS_FILEID(inode),
+                        data->args.count,
+                        (unsigned long long)data->args.offset);
+
+        task = rpc_run_task(&task_setup_data);
+        if (IS_ERR(task))
+                return PTR_ERR(task);
+        rpc_put_task(task);
+        return 0;
+}
+
+/*
+ * Set up the NFS read request struct
+ */
+static int nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
+                const struct rpc_call_ops *call_ops,
+                unsigned int count, unsigned int offset,
+                struct pnfs_layout_segment *lseg)
+{
+        struct inode *inode = req->wb_context->path.dentry->d_inode;
+
         data->req         = req;
         data->inode       = inode;
-        data->cred        = msg.rpc_cred;
+        data->cred        = req->wb_context->cred;
         data->lseg        = get_lseg(lseg);
 
         data->args.fh     = NFS_FH(inode);
@@ -199,21 +224,11 @@ static int nfs_read_rpcsetup(struct nfs_page *req, struct nfs_read_data *data,
         data->res.eof     = 0;
         nfs_fattr_init(&data->fattr);
 
-        /* Set up the initial task struct. */
-        NFS_PROTO(inode)->read_setup(data, &msg);
-
-        dprintk("NFS: %5u initiated read call (req %s/%Ld, %u bytes @ offset %Lu)\n",
-                        data->task.tk_pid,
-                        inode->i_sb->s_id,
-                        (long long)NFS_FILEID(inode),
-                        count,
-                        (unsigned long long)data->args.offset);
+        if (data->lseg &&
+            (pnfs_try_to_read_data(data, call_ops) == PNFS_ATTEMPTED))
+                return 0;
 
-        task = rpc_run_task(&task_setup_data);
-        if (IS_ERR(task))
-                return PTR_ERR(task);
-        rpc_put_task(task);
-        return 0;
+        return nfs_initiate_read(data, NFS_CLIENT(inode), call_ops);
 }
 
 static void
diff --git a/include/linux/nfs_iostat.h b/include/linux/nfs_iostat.h
index 68b10f5f8907..37a143732d02 100644
--- a/include/linux/nfs_iostat.h
+++ b/include/linux/nfs_iostat.h
@@ -113,6 +113,7 @@ enum nfs_stat_eventcounters {
         NFSIOS_SHORTREAD,
         NFSIOS_SHORTWRITE,
         NFSIOS_DELAY,
+        NFSIOS_PNFS_READ,
         __NFSIOS_COUNTSMAX,
 };
 
diff --git a/include/linux/nfs_xdr.h b/include/linux/nfs_xdr.h
index 560923e28723..9d2b9dae277d 100644
--- a/include/linux/nfs_xdr.h
+++ b/include/linux/nfs_xdr.h
@@ -1018,6 +1018,7 @@ struct nfs_read_data {
         struct nfs_readres  res;
         unsigned long           timestamp;      /* For lease renewal */
         struct pnfs_layout_segment *lseg;
+        const struct rpc_call_ops *mds_ops;
         struct page             *page_array[NFS_PAGEVEC_SIZE];
 };