5 files changed, 190 insertions, 0 deletions

diff --git a/fs/nfs/file.c b/fs/nfs/file.c
index c3f2477c16c1..91d019d39122 100644
--- a/fs/nfs/file.c
+++ b/fs/nfs/file.c
@@ -36,6 +36,7 @@
 #include "internal.h"
 #include "iostat.h"
 #include "fscache.h"
+#include "pnfs.h"
 
 #define NFSDBG_FACILITY         NFSDBG_FILE
 
@@ -386,6 +387,10 @@ static int nfs_write_begin(struct file *file, struct address_space *mapping,
                 file->f_path.dentry->d_name.name,
                 mapping->host->i_ino, len, (long long) pos);
 
+        pnfs_update_layout(mapping->host,
+                           nfs_file_open_context(file),
+                           IOMODE_RW);
+
 start:
         /*
          * Prevent starvation issues if someone is doing a consistency
diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c
index 6eec28656415..314f57164602 100644
--- a/fs/nfs/inode.c
+++ b/fs/nfs/inode.c
@@ -48,6 +48,7 @@
 #include "internal.h"
 #include "fscache.h"
 #include "dns_resolve.h"
+#include "pnfs.h"
 
 #define NFSDBG_FACILITY         NFSDBG_VFS
 
@@ -1410,6 +1411,7 @@ void nfs4_evict_inode(struct inode *inode)
 {
         truncate_inode_pages(&inode->i_data, 0);
         end_writeback(inode);
+        pnfs_destroy_layout(NFS_I(inode));
         /* If we are holding a delegation, return it! */
         nfs_inode_return_delegation_noreclaim(inode);
         /* First call standard NFS clear_inode() code */
@@ -1447,6 +1449,7 @@ static inline void nfs4_init_once(struct nfs_inode *nfsi)
         nfsi->delegation = NULL;
         nfsi->delegation_state = 0;
         init_rwsem(&nfsi->rwsem);
+        nfsi->layout = NULL;
 #endif
 }
 
diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index cf795625610e..c0cd954855b9 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -166,3 +166,143 @@ pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *ld_type)
         spin_unlock(&pnfs_spinlock);
 }
 EXPORT_SYMBOL_GPL(pnfs_unregister_layoutdriver);
+
+static void
+get_layout_hdr_locked(struct pnfs_layout_hdr *lo)
+{
+        assert_spin_locked(&lo->inode->i_lock);
+        lo->refcount++;
+}
+
+static void
+put_layout_hdr_locked(struct pnfs_layout_hdr *lo)
+{
+        assert_spin_locked(&lo->inode->i_lock);
+        BUG_ON(lo->refcount == 0);
+
+        lo->refcount--;
+        if (!lo->refcount) {
+                dprintk("%s: freeing layout cache %p\n", __func__, lo);
+                NFS_I(lo->inode)->layout = NULL;
+                kfree(lo);
+        }
+}
+
+void
+pnfs_destroy_layout(struct nfs_inode *nfsi)
+{
+        struct pnfs_layout_hdr *lo;
+
+        spin_lock(&nfsi->vfs_inode.i_lock);
+        lo = nfsi->layout;
+        if (lo) {
+                /* Matched by refcount set to 1 in alloc_init_layout_hdr */
+                put_layout_hdr_locked(lo);
+        }
+        spin_unlock(&nfsi->vfs_inode.i_lock);
+}
+
+/* STUB - pretend LAYOUTGET to server failed */
+static struct pnfs_layout_segment *
+send_layoutget(struct pnfs_layout_hdr *lo,
+           struct nfs_open_context *ctx,
+           u32 iomode)
+{
+        struct inode *ino = lo->inode;
+
+        set_bit(lo_fail_bit(iomode), &lo->state);
+        spin_lock(&ino->i_lock);
+        put_layout_hdr_locked(lo);
+        spin_unlock(&ino->i_lock);
+        return NULL;
+}
+
+static struct pnfs_layout_hdr *
+alloc_init_layout_hdr(struct inode *ino)
+{
+        struct pnfs_layout_hdr *lo;
+
+        lo = kzalloc(sizeof(struct pnfs_layout_hdr), GFP_KERNEL);
+        if (!lo)
+                return NULL;
+        lo->refcount = 1;
+        lo->inode = ino;
+        return lo;
+}
+
+static struct pnfs_layout_hdr *
+pnfs_find_alloc_layout(struct inode *ino)
+{
+        struct nfs_inode *nfsi = NFS_I(ino);
+        struct pnfs_layout_hdr *new = NULL;
+
+        dprintk("%s Begin ino=%p layout=%p\n", __func__, ino, nfsi->layout);
+
+        assert_spin_locked(&ino->i_lock);
+        if (nfsi->layout)
+                return nfsi->layout;
+
+        spin_unlock(&ino->i_lock);
+        new = alloc_init_layout_hdr(ino);
+        spin_lock(&ino->i_lock);
+
+        if (likely(nfsi->layout == NULL))       /* Won the race? */
+                nfsi->layout = new;
+        else
+                kfree(new);
+        return nfsi->layout;
+}
+
+/* STUB - LAYOUTGET never succeeds, so cache is empty */
+static struct pnfs_layout_segment *
+pnfs_has_layout(struct pnfs_layout_hdr *lo, u32 iomode)
+{
+        return NULL;
+}
+
+/*
+ * Layout segment is retreived from the server if not cached.
+ * The appropriate layout segment is referenced and returned to the caller.
+ */
+struct pnfs_layout_segment *
+pnfs_update_layout(struct inode *ino,
+                   struct nfs_open_context *ctx,
+                   enum pnfs_iomode iomode)
+{
+        struct nfs_inode *nfsi = NFS_I(ino);
+        struct pnfs_layout_hdr *lo;
+        struct pnfs_layout_segment *lseg = NULL;
+
+        if (!pnfs_enabled_sb(NFS_SERVER(ino)))
+                return NULL;
+        spin_lock(&ino->i_lock);
+        lo = pnfs_find_alloc_layout(ino);
+        if (lo == NULL) {
+                dprintk("%s ERROR: can't get pnfs_layout_hdr\n", __func__);
+                goto out_unlock;
+        }
+
+        /* Check to see if the layout for the given range already exists */
+        lseg = pnfs_has_layout(lo, iomode);
+        if (lseg) {
+                dprintk("%s: Using cached lseg %p for iomode %d)\n",
+                        __func__, lseg, iomode);
+                goto out_unlock;
+        }
+
+        /* if LAYOUTGET already failed once we don't try again */
+        if (test_bit(lo_fail_bit(iomode), &nfsi->layout->state))
+                goto out_unlock;
+
+        get_layout_hdr_locked(lo);
+        spin_unlock(&ino->i_lock);
+
+        lseg = send_layoutget(lo, ctx, iomode);
+out:
+        dprintk("%s end, state 0x%lx lseg %p\n", __func__,
+                nfsi->layout->state, lseg);
+        return lseg;
+out_unlock:
+        spin_unlock(&ino->i_lock);
+        goto out;
+}
diff --git a/fs/nfs/pnfs.h b/fs/nfs/pnfs.h
index 61531f338576..4ed1b48c71b1 100644
--- a/fs/nfs/pnfs.h
+++ b/fs/nfs/pnfs.h
@@ -34,6 +34,11 @@
 
 #define LAYOUT_NFSV4_1_MODULE_PREFIX "nfs-layouttype4"
 
+enum {
+        NFS_LAYOUT_RO_FAILED = 0,       /* get ro layout failed stop trying */
+        NFS_LAYOUT_RW_FAILED,           /* get rw layout failed stop trying */
+};
+
 /* Per-layout driver specific registration structure */
 struct pnfs_layoutdriver_type {
         struct list_head pnfs_tblid;
@@ -44,14 +49,48 @@ struct pnfs_layoutdriver_type {
         int (*uninitialize_mountpoint) (struct nfs_server *);
 };
 
+struct pnfs_layout_hdr {
+        unsigned long           refcount;
+        unsigned long           state;
+        struct inode            *inode;
+};
+
 extern int pnfs_register_layoutdriver(struct pnfs_layoutdriver_type *);
 extern void pnfs_unregister_layoutdriver(struct pnfs_layoutdriver_type *);
 
+struct pnfs_layout_segment *
+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 *);
+void pnfs_destroy_layout(struct nfs_inode *);
+
+
+static inline int lo_fail_bit(u32 iomode)
+{
+        return iomode == IOMODE_RW ?
+                         NFS_LAYOUT_RW_FAILED : NFS_LAYOUT_RO_FAILED;
+}
+
+/* Return true if a layout driver is being used for this mountpoint */
+static inline int pnfs_enabled_sb(struct nfs_server *nfss)
+{
+        return nfss->pnfs_curr_ld != NULL;
+}
 
 #else  /* CONFIG_NFS_V4_1 */
 
+static inline void pnfs_destroy_layout(struct nfs_inode *nfsi)
+{
+}
+
+static inline struct pnfs_layout_segment *
+pnfs_update_layout(struct inode *ino, struct nfs_open_context *ctx,
+                   enum pnfs_iomode access_type)
+{
+        return NULL;
+}
+
 static inline void set_pnfs_layoutdriver(struct nfs_server *s, u32 id)
 {
 }
diff --git a/fs/nfs/read.c b/fs/nfs/read.c
index 79859c81a943..e4b62c6f5a6e 100644
--- a/fs/nfs/read.c
+++ b/fs/nfs/read.c
@@ -25,6 +25,7 @@
 #include "internal.h"
 #include "iostat.h"
 #include "fscache.h"
+#include "pnfs.h"
 
 #define NFSDBG_FACILITY         NFSDBG_PAGECACHE
 
@@ -120,6 +121,7 @@ int nfs_readpage_async(struct nfs_open_context *ctx, struct inode *inode,
         len = nfs_page_length(page);
         if (len == 0)
                 return nfs_return_empty_page(page);
+        pnfs_update_layout(inode, ctx, IOMODE_READ);
         new = nfs_create_request(ctx, inode, page, 0, len);
         if (IS_ERR(new)) {
                 unlock_page(page);
@@ -624,6 +626,7 @@ int nfs_readpages(struct file *filp, struct address_space *mapping,
         if (ret == 0)
                 goto read_complete; /* all pages were read */
 
+        pnfs_update_layout(inode, desc.ctx, IOMODE_READ);
         if (rsize < PAGE_CACHE_SIZE)
                 nfs_pageio_init(&pgio, inode, nfs_pagein_multi, rsize, 0);
         else