[PATCH 1/2] SQUASHME pnfs-submit: reinitialize pnfs_layout_type

[andros@netapp.com]

From: Andy Adamson <andros@netapp.com>

We do not free the pnfs_layout_type when the layout segment list is empty, but
we do remove the layout from the nfs_client cl_layouts list, and we also need
to re-initialize it. The next LAYOUTGET will set the layout values.

Note: API change: layoutdriver_io_operations free_layout now has a boolean
to indicate initiaize_only, do not free.

Signed-off-by: Andy Adamson <andros@netapp.com>
---
 fs/nfs/pnfs.c             |   30 ++++++++++++++++++++++++++++--
 include/linux/nfs4_pnfs.h |    5 ++++-
 2 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c
index 6832237..d8887ef 100644
--- a/fs/nfs/pnfs.c
+++ b/fs/nfs/pnfs.c
@@ -337,7 +337,7 @@ put_layout_locked(struct pnfs_layout_type *lo)
 
 		dprintk("%s: freeing layout cache %p\n", __func__, lo);
 		WARN_ON(!list_empty(&lo->lo_layouts));
-		io_ops->free_layout(lo);
+		io_ops->free_layout(lo, false);
 		nfsi->layout = NULL;
 	}
 }
@@ -658,6 +658,31 @@ _pnfs_can_return_lseg(struct pnfs_layout_segment *lseg)
 	return atomic_read(&lseg->kref.refcount) == 1;
 }
 
+/*
+ * We don't free the pnfs_layout_type upon last LAYOUTRETURN, but we do
+ * un-initialize.  lo->segs is empty, and the layout has been removed from
+ * lo_layouts. Leave the lo->refcount un-touched.
+ *
+ * Called with inode->i_lock held.
+ *
+ * There still might be an outstanding async LAYOUTCOMMIT, but that's OK
+ * because the pnfs_layout_type is not referenced (exept for the refcount)
+ * by layoutcommit rpc_release.
+ *
+ * Call the layoutdriver free_layout with the initialze-only parameter set
+ * to true.
+ */
+static void nfs4_uninitialize_layout(struct pnfs_layout_type *lo)
+{
+	dprintk("--> %s lo->refcount %d\n", __func__, lo->refcount);
+	lo->roc_iomode = 0;
+	pnfs_set_layout_stateid(lo, &zero_stateid);
+	lo->pnfs_layout_state = 0;
+	lo->pnfs_write_begin_pos = 0;
+	lo->pnfs_write_end_pos = 0;
+	/* True means initialize, do not free the layout */
+	PNFS_LD_IO_OPS(lo)->free_layout(lo, true);
+}
 
 static void
 pnfs_free_layout(struct pnfs_layout_type *lo,
@@ -686,6 +711,7 @@ pnfs_free_layout(struct pnfs_layout_type *lo,
 		spin_lock(&clp->cl_lock);
 		list_del_init(&lo->lo_layouts);
 		spin_unlock(&clp->cl_lock);
+		nfs4_uninitialize_layout(lo);
 	}
 
 	dprintk("%s:Return\n", __func__);
@@ -959,7 +985,7 @@ nfs_lock_alloc_layout(struct inode *ino)
 		/* Reference the layout accross i_lock release and grab */
 		get_layout(NFS_I(ino)->layout);
 		spin_unlock(&ino->i_lock);
-		NFS_SERVER(ino)->pnfs_curr_ld->ld_io_ops->free_layout(new);
+		PNFS_LD_IO_OPS(NFS_I(ino)->layout)->free_layout(new, false);
 		spin_lock(&ino->i_lock);
 		put_layout_locked(NFS_I(ino)->layout);
 	}
diff --git a/include/linux/nfs4_pnfs.h b/include/linux/nfs4_pnfs.h
index 2c6ce4c..70e80cd 100644
--- a/include/linux/nfs4_pnfs.h
+++ b/include/linux/nfs4_pnfs.h
@@ -145,7 +145,10 @@ struct layoutdriver_io_operations {
 	 * inode specific layout structure.  Each subsequent layoutget operation results in
 	 * a set_layout call to set the opaque layout in the layout driver.*/
 	struct pnfs_layout_type * (*alloc_layout) (struct inode *inode);
-	void (*free_layout) (struct pnfs_layout_type *);
+
+	/* init_only true, means do not free the layout, just re-initialize */
+	void (*free_layout) (struct pnfs_layout_type *, bool init_only);
+
 	struct pnfs_layout_segment * (*alloc_lseg) (struct pnfs_layout_type *layoutid, struct nfs4_pnfs_layoutget_res *lgr);
 	void (*free_lseg) (struct pnfs_layout_segment *lseg);
 
-- 
1.6.6