1 files changed, 140 insertions, 0 deletions

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;
+}